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W9ASS
11-11-2007, 02:08 AM
Good evening gentlemen,

I am asking this question on behalf of a new amateur that I met on the air a few days back:

This gentleman owns a Palomar 250 linear amplifier, which was made for 10 meters (but probably wasnt being used for that band originally). The amplifier, when bought new, can be used on AM/FM/CW. His question is, can this amplifier be modified to operate SSB, and if so, how? I have looked around the web a little and did not see very much in regards to this type of subject. He mentioned that he had bought a cheap 10 meter radio and wanted to use the Palomar for SSB usage but found out that it wouldnt work that way...Any ideas?

Thanks again for your help! Just a basic outline of the process should do it, you dont have to totally hold my hand on this one, its just that amp conversions are not my specialty when it comes to radio....

73,

KC9DGM

N2RJ
11-11-2007, 02:09 AM
It sounds like a CB amp.

I wouldn't use it on any ham band. It probably wouldn't be legal to run anyway.

WB2WIK
11-11-2007, 02:25 AM
Bingo! Ryan wins the kewpee doll. It is a CB amp and is not for legitimate use in the amateur bands at all -- and of course was completely illegal to use on CB also.

BTW, any amplifier that's good for "AM" is also good for SSB, since both modes are indeed AM (just different types of AM) and require good linearity. Problem is, the Palomar (as well as a hundred other "brands" of CB amplifiers) aren't the slightest bit linear and will sound like crap.

WB2WIK/6

AG3Y
11-11-2007, 02:28 AM
The question about Polomar and other 11 meter amps comes up so often here on the ZED, that we OFs are getting tired of answering it .

The thing is a piece of junk, made for illegal operation on the CB and freebands, is designed with cheapness as the top priority, and since it is knowingly built for illegal trade, little or no consideration is made toward its spectral purity or distortion free operation!

That is why it should NOT be used for any reason on a ham band! You or your friend could very possibly lose your licenses for operating outside of the technical specifications for the Amateur Radio Service.

"A word to the wise is sufficient ! " 73, Jim

KA9VQF
11-11-2007, 03:07 AM
While I agree that it is junk and should not be used by any amateur who wants to keep his license, you can remove the cover on the relay that keeps chattering while you try to talk on SSB the take a Popsicle stick and hold the relay down while you talk.

Don’t ask me how I know this will work





{I only did it once I swear.}

WB2UAQ
11-11-2007, 03:34 AM
I'd like to raise a few points or questions about the use of the these amps.

I 've been tempted to buy them from time to time at hamfests because they are very inexpensive AND they might be the basis for a legitimate amateur band amplifier after some re-work of course.

The one's I have looked at have more or less standard broadband input and output transformers. They all completely lack a low pass filter. They are probably lacking a proper bias regulator if they have any at all.

I have worked on many amateur band PA's and these illegal CB units are not that different except for the above mentioned issues.

As licensed amateur radio operators I don't see why we could not re-engineer one of these units for our own personal use (not for re-sale whatsoever) within the amateur bands. Add a low pass filter, add a bias regulator, test the spectral purity to be sure they meet current standards (harmonics and IMD), etc.( I am sure there are other short-comings). They have the basic ingredients, a circuit board, a pair of RF power transistors, the broadband transformers and a heatsink/case. I would not even put the unit on 10 meters.

Many will probably think this is not worth effort however, as an amateur radio operator, I put much more time into tinkering and learning about things than actually operating. I see alot of guys spend alot of time on QRZ.
I bet they spend more time here than the operating their rigs.

73, Pete

WB7DMX
11-11-2007, 04:23 AM
sometimes the questions and answers on here are very silly.

until someone can prove me wrong, any ham radio operator can build, modify, any piece of equipment for armature use as long as it conforms to the rules and regulations for the amateur service for the class of liceness one holds

one should have the knowledge and proper test equipment to do this in the proper manner.

as far as I know, there is nothing that can not be used in the amateur service, I have used old surplus military equipment, western union equipment and bell telephone repeaters, commercial Motorola transceivers in my many years of amateur radio.

WA9SVD
11-11-2007, 04:38 AM
Pete,
What you say is true... In theory. But it's easier said than done. Adding a proper bias circuit is often difficult given the circuit board layout, and there's often insufficient room inside such amps for the proper output filters; without band switching, it would only be suitable for use on a single band. (While an external filter system could be devised, it pretty much negates the convenience of such an amp and creates an additional project in and of itself.
In addition, most Amateurs do NOT have sufficient test equipment to adjust an amplifier and ensure that it operates within the Amateur Technical Standards set forth in §Part 97.307.

Also realize that the "POWER" rating claimed by the CB amp dealers is most often wildly exaggerated, and the power in TRUE linear service, (provided it can be reasonably achieved,) is usually considerably less. Considering most modern Amateur transceivers are already rated a nominal 100 Watts output, it's questionable whether even using a "CB" type amp would be of any real benefit. (So in that case, no, it would NOT be worth the effort.) Certainly, as an educational exercise it may have value, but probably not very useful.

K7JEM
11-11-2007, 04:50 AM
I actually have a Palomar 225 around here somewhere, bought it about 10 years ago to add to my RS HTX100 mobile.

Worked pretty good, got about 150 watts out with 5 watts of drive, made tons of contacts with it.

As amateurs, our license allows us to use homebrew or modified equipment as long as we stay within technical parameters.

Whether or not YOU can determine if an amplifier is suitable for use is up to your own abilities and test equipment.

Joe

N8YX
11-11-2007, 12:47 PM
Quote[/b] (wb2uaq @ Nov. 10 2007,20:34)]I have worked on many amateur band PA's and these illegal CB units are not that different except for the above mentioned issues.
Swan/Cubic's Astro series of HF SSB/CW transceivers employed a PA brick that was based on a design from Motorola's "RF Application Notes" publication. They did not use output filtering; rather, several stages of input filtering were employed earlier on in the TX RF chain.

I have seen a number of so-called "CB Amps" that were virtual carbon copies of the Cubic 'brick'. Including the biasing circuitry and so forth. Most of these employed a pair of MRF458s for output devices, just like the original Motorola design.

The few modern designs I've inspected differ markedly from their earlier cousins, especially where biasing and design of the input/output matching circuits are concerned. As such, most would require extensive rework before they could be "legally" used on the ham bands...

K9STH
11-11-2007, 04:07 PM
DMX:

Actually, anyone can build or modify anything for armature work! Electric motors are not covered by FCC regulations.

Now for amateur radio work, that is another matter!

http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif

Glen, K9STH

WB7DMX
11-11-2007, 04:23 PM
Quote[/b] (K9STH @ Nov. 11 2007,09:07)]DMX:

Actually, anyone can build or modify anything for armature work! #Electric motors are not covered by FCC regulations.

Now for amateur radio work, that is another matter!

http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif

Glen, K9STH
so what is to stop anyone from rewinding any electric motor ? and using it.

W5HTW
11-11-2007, 04:33 PM
Motors often are "flat out" devices, not very linear. Either OFF or Full Speed Ahead. Adding variable speed to one to make it more linear could prove difficult. Some claim to be linear and operate at different speeds, but few are continuously variable so as to be truly linear. Some of them, if you reverse polarity, you wind up sucking the RF from the air and into your antenna. This spills onto your desk and can actually clog the air in your room. The purity of such RF clogged air is doubtful at best, especially in a confined space.

You can, though, use an old CB linear to drive a motor, but it is not very efficient. It takes about 800 pounds to get the motor up to a single 10-4, and overkermodchicating is common.

I am strongly against radiating armatures, AC, DC, or switch hitters.

Ed

WB7DMX
11-11-2007, 04:38 PM
Quote[/b] (W5HTW @ Nov. 11 2007,09:33)]Motors often are "flat out" devices, not very linear. #Either OFF or Full Speed Ahead. #Adding variable speed to one to make it more linear could prove difficult. #Some claim to be linear and operate at different speeds, but few are continuously variable so as to be truly linear. # Some of them, if you reverse polarity, you wind up sucking the RF from the air and into your antenna. #This spills onto your desk and can actually clog the air in your room. # The purity of such RF clogged air is doubtful at best, especially in a confined space. #

You can, though, use an old CB linear to drive a motor, but it is not very efficient. #It takes about 800 pounds to get the motor up to a single 10-4, and overkermodchicating is common. #

I am strongly against radiating armatures, AC, DC, or switch hitters. #

Ed
OK
that makes sence.

K7FE
11-11-2007, 05:04 PM
Quote[/b] (wb2uaq @ Nov. 10 2007,20:34)]I'd like to raise a few points or questions about the use of the these amps.

I 've been tempted to buy them from time to time at hamfests because they are very inexpensive AND they might be the basis for a legitimate amateur band amplifier after some re-work of course.

The one's I have looked at have more or less standard broadband input and output transformers. They all completely lack a low pass filter. They are probably lacking a proper bias regulator if they have any at all.

I have worked on many amateur band PA's and these illegal CB units are not that different except for the above mentioned issues.

As licensed amateur radio operators I don't see why we could not re-engineer one of these units for our own personal use (not for re-sale whatsoever) within the amateur bands. Add a low pass filter, add a bias regulator, test the spectral purity to be sure they meet current standards (harmonics and IMD), etc.( I am sure there are other short-comings). They have the basic ingredients, a circuit board, a pair of RF power transistors, the broadband transformers and a heatsink/case. I would not even put the unit on 10 meters.

Many will probably think this is not worth effort however, as an amateur radio operator, I put much more time into tinkering and learning about things than actually operating. I see alot of guys spend alot of time on QRZ.
I bet they spend more time here than the operating their rigs.

73, Pete
Pete, You have made a good point.
These CB amps can be used for the parts and box to build a decent amateur band amplifier. The fan, heat sink and usually the transistors may be used. Often the broad band transformers are fine. It takes a long time to drill, tap and cut boxes and heat sinks so starting with those things done saves a lot of time.

The CB amp's usually lack base bias for the transistors and this can be built easily. An adjustable 0.5 to 1.5 volt supply, with a 1/2 amp capability will give you the range to set the bias for a pair of bipolar transistors in a "linear" region. The amplifier will then be useful for amateur SSB operation. If your amp has more than two transistors, use 1/2 amp per pair as a guide. Each transistor pair should have it's own bias regulated supply to allow proper linear adjustment for each pair. The bias regulator can be an IC driving a "pass" transistor. A method of feeding back the main heatsink temperature to the bias supply is important, so that the final transistors do not go into thermal runaway. This is often done with a diode mounted on the heat sink.

Filtering can be done outside the amplifier housing with a bandpass filter built into a small box for each band of interest. I built band pass filter boxes with female BNC connectors on them for my work bench projects. One larger box could contain several switchable filters.

CB amps can make great project boxes for VHF or UHF amplifiers also. Think creatively.

73,
Terry, K7FE

W4INF
11-11-2007, 05:56 PM
SSB should be able to be operated in the CW selection. Most of the other amps are labeled (CW/SSB) and (AM) on a selector switch.

HTH,
Andrew

K7FE
11-11-2007, 06:28 PM
Quote[/b] (W4INF @ Nov. 11 2007,10:56)]SSB should be able to be operated in the CW selection. Most of the other amps are labeled (CW/SSB) and (AM) on a selector switch.

HTH,
Andrew
This is really not the case. The AM - CW/SSB position switch often adds an attenuator on the input side of the amplifier (for AM) and would not add bias to the base of the transistors in either position. The CW/SSB position keeps the relay closed in the transmit position a little longer (a second or two) than when in the AM mode.

In a CW mode, the amplifier could be class C, and would not require ABxx as SSB does.

Class C is less expensive to build. Less parts. That is why they are built that way. Many non- technical CB users do not know the difference or are only concerned with the output power for a "dead carrier" signal strength contest/use.

The specifications of most CB gear (of all types) is subject to gross exaggeration about performance. 300 watt linear amplifiers may only provide 100 watts and not be "linear." Antennas may have no gain or negative gain and be advertised as 3dB gain antennas. I have seen advertised "5/8 wave antennas" that are only 1/4 wave long. The commercial CB market is a real "caveat emptor " area.

73,
Terry, K7FE

WB2UAQ
11-11-2007, 11:21 PM
Thanks for all of the replys to my comments. The points you guys made are very good. We can still tinker and put our homebrewed stuff on the air unlike any other radio service. It is a privledge that needs to be preserved.
When the hamfests start up again in the spring, I might latch on to one of those old nasty amplifiers and give it a new and better life:)
73,
Pete

KA4DPO
11-12-2007, 12:15 AM
Quote[/b] (wb2uaq @ Nov. 11 2007,18:21)]Thanks for all of the replys to my comments. #The points you guys made are very good. # We can still tinker and put our homebrewed stuff on the air unlike any other radio service. #It is a privledge that needs to be preserved.
When the hamfests start up again in the spring, I might latch on to one of those old nasty amplifiers and give it a new and better life:)
73,
Pete
If you can cut the drive power down to a couple of watts there's no reason that it wont work. However, I would look at the two tone output on a spectrum analyzer before I put it on the air.

N2RJ
11-12-2007, 12:34 AM
I think the problem is that these amps are RF keyed, and because they are RF keyed, SSB would make the relay chatter instead of staying "on".

WB2UAQ
11-12-2007, 01:22 AM
An earlier comment mentioned the relay delay to prevent the t/r relay from chattering.
The application for me would be CW only on 3.5,7,14 and 21 Mc. For many years I was thinking about adding a PA after my old HW-8. Two tone testing wouldn't be needed. Harmonics and spurs would be the concern.

W9ASS
11-12-2007, 01:32 AM
Gentlemen,

The reason I asked this question was because I was doing a favor to a radio friend of mine who just got his ticket this Thursday. He has a Yaesu 10 meter rig and wants to find out how to modify the Palomar to work on SSB for 10 meters.

I am really surprised how fast some of you guys jump the gun and assume that people with lower class licenses are somehow up to no good. If you arent aware already, it IS LEGAL to operate SSB between 28.3 to 28.5 if you are technician class licensee. In fact, I am operating 10 meters already, and I love it.


73,

KC9DGM

WA9SVD
11-12-2007, 01:56 AM
Quote[/b] (KC9DGM @ Nov. 11 2007,18:32)]Gentlemen,

The reason I asked this question was because I was doing a favor to a radio friend of mine who just got his ticket this Thursday. He has a Yaesu 10 meter rig and wants to find out how to modify the Palomar to work on SSB for 10 meters.

I am really surprised how fast some of you guys jump the gun and assume that people with lower class licenses are somehow up to no good. If you arent aware already, it IS LEGAL to operate SSB between 28.3 to 28.5 if you are technician class licensee. In fact, I am operating 10 meters already, and I love it.

Some of you guys really disappoint me. Maybe you should stop being some rude and judgemental and just try and open that mind of yours, which happens to be rusted shut.

73,

KC9DGM
Then you misunderstand the replies.

No one here said there was anything "illegal" or wrong with operating SSB on 10 Meters, or with using an amplifier for SSB on 10 Meter, as long as:

1. It is below the legal power output limit, (which I believe for Novice and Tech on 10 Meters is 200 Watts; other class licensees may use up to 1500 Watts output on 10 Meters.)

2. It complies with the Technical Standards outlined in §Part97.307, which specifies allowable distortion and spectral purity standards for Amateur equipment.

What we DID point out is that the "typical" CB amplifier probably does NOT operate in a linear amplification mode, and will have unacceptable distortion. Also, the typical CB amp will have inadequate filtering (or none at all) to reduce harmonic energy, as well as other out-of-band signals that are a product of non-linear operation.
We also described what would typically be required to make such an amp perform acceptably in the Amateur Service.

I can't see how you can take offense by the replies, as no one accused YOU or your friend of anything improper.

Now, if you DO want to modify such a "CB" amp for Amateur Service, you will need test equipment (either your own or access to the equipment of a friend or fellow Amateur) to ensure it DOES comply with the regulations. That would normally include at least a series of tests with a spectrum analyzer to ensure the spectral purity is within standards, (whether such an amp is used for CW in Class "C" operation, or if it's used (in your case) for SSB in linear (Class A, AB1,B) mode. Without such testing, you can't know if the amp's output is sufficiently clean to be operated legally.

N2RJ
11-12-2007, 02:27 AM
Quote[/b] (KC9DGM @ Nov. 11 2007,20:32)]Gentlemen,

The reason I asked this question was because I was doing a favor to a radio friend of mine who just got his ticket this Thursday. He has a Yaesu 10 meter rig and wants to find out how to modify the Palomar to work on SSB for 10 meters.

I am really surprised how fast some of you guys jump the gun and assume that people with lower class licenses are somehow up to no good. If you arent aware already, it IS LEGAL to operate SSB between 28.3 to 28.5 if you are technician class licensee. In fact, I am operating 10 meters already, and I love it.


73,

KC9DGM
The legality of operating SSB is not what is under question.

The legality of running a CB amp is what is under question.

Most CB amps will not output a signal that is within FCC spec for the amateur service.

This has nothing to do with technicians, no code, newbies, lower class licensees or anything like that. It has to do with spectral purity of a transmitted signal.

Yes, there are still some of us left that care about how our signal appears to the outside world.

WA9SVD
11-12-2007, 02:48 AM
Quote[/b] (N2RJ @ Nov. 11 2007,19:27)]
Quote[/b] (KC9DGM @ Nov. 11 2007,20:32)]Gentlemen,

The reason I asked this question was because I was doing a favor to a radio friend of mine who just got his ticket this Thursday. He has a Yaesu 10 meter rig and wants to find out how to modify the Palomar to work on SSB for 10 meters.

I am really surprised how fast some of you guys jump the gun and assume that people with lower class licenses are somehow up to no good. If you arent aware already, it IS LEGAL to operate SSB between 28.3 to 28.5 if you are technician class licensee. In fact, I am operating 10 meters already, and I love it.


73,

KC9DGM
The legality of operating SSB is not what is under question.

The legality of running a CB amp is what is under question.

Most CB amps will not output a signal that is within FCC spec for the amateur service.

This has nothing to do with technicians, no code, newbies, lower class licensees or anything like that. It has to do with spectral purity of a transmitted signal.

Yes, there are still some of us left that care about how our signal appears to the outside world.
And that's WHY several of us pointed out quite specifically that proper biasing AND FILTERING would have to be added to the "typical" CB amp to be used legally.

KA9VQF
11-12-2007, 04:28 AM
Sometime ago I got my tech plus license. I already had a novice license and had made the purchase of a Tempo One transceiver.

This particular radio had been hacked so it was a “Big Radio” on the CB band. The fellow I bought it from had restored it so it no longer functioned on the 11M band, he also built a power supply since the original had been pretty well reduced to ash by the former owner.

Now this homebrew power supply was a bit short on output for the rig and the finals were weak to begin with. On a good day it would put around 50 watts into the dummy load and probably that much into an antenna on ten meters.

As it happened we were in a bodacious sunspot cycle and I worked a lot of stations using my rudimentary antenna made out of a 2X2 and TV tape.

Conditions were so darn good that pretty much if I could hear them I could work them even with out my bucket being full.{100 watts with fresh finals on the Tempo One}

As time went on the power output began to taper off. I looked around for replacement tubes and a replacement power supply for the rig. I found them but they were out of my price range.

I found a construction article in a QST about how to build a 50 watt amplifier and built same. I did some of my best work ever on that project. It came out well and the Tempo still had enough starch in its sox to drive it pretty well. This was a temporary arrangement, just until I could afford to buy the new finals {yeah right}

It got to where I only had maybe three watts out of the Tempo. This was not enough to drive my little amp. That is where the CB amp came in they don’t need 20 watts input to put out their full power. Three watts gave me around 30 watts output on 10M. The sunspot cycle had turned and pretty well bottomed out when I finally gave up.

I returned the CB amp and put the Tempo on a shelf in the attic.

Strange how I eventually bought a different HF rig or two and still haven’t gotten the tubes to make the Tempo go.

KA5S
11-12-2007, 07:30 AM
Some decades ago I got one of these that had been properly linearized by a technically competent ham of my acquaintance. Still needed a filter.

Not all transistors are rated for linear operation, and a transistor meant for Class C operation can fail in unique ways.

Anyway, here's a link (http://nr6ca.org/ab-bias.html)to "CONVERTING SOLID STATE CLASS C AMPLFIERS TO LINEAR OPERATION".

FWIW, there is a way to amplify SSB with a Class C amplifier. You set the bias so the SSB signal is heavily clipped, but also detect the envelope of the driving signal separately -- and 100 percent amplitude modulate the amplifier with that signal. More trouble than it's worth IMO!



Cortland
KA5S

W9ASS
11-12-2007, 03:58 PM
Gentlemen,

Thanks for the help so far. I'm just glad its not my amplifier! http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

Sorry if I jumped the gun and got pissed off too. I'm guilty of doing the same thing some hams do here when they suspect something is shady afoot. This hobby is a learning experience, and thats exactly what I'm doing.

I shall relay the info, or better yet, I will tell my radio friend that there is a lengthy thread on QRZ that he will have to read, as I dont feel like reading every reply over the air! (I limit my 11 meter transmissions to less than 2 minutes at a time, thank God for my timer!)

73,

KC9DGM

11-12-2007, 06:50 PM
Quote[/b] (KC9DGM @ Nov. 11 2007,18:32)]Gentlemen,

The reason I asked this question was because I was doing a favor to a radio friend of mine who just got his ticket this Thursday. He has a Yaesu 10 meter rig and wants to find out how to modify the Palomar to work on SSB for 10 meters.

I am really surprised how fast some of you guys jump the gun and assume that people with lower class licenses are somehow up to no good. If you arent aware already, it IS LEGAL to operate SSB between 28.3 to 28.5 if you are technician class licensee. In fact, I am operating 10 meters already, and I love it.


73,

KC9DGM
You are not reading the others posts correctly. There are technical standards for amateur radio equipment that is used by amateurs in the FCC rules. The odds are that the amplifier in question would not meet theses standards. It is up to the individual amateur operator to insure their equipment meet the standards.

Only testing with a two tone signal generator and a spectrum analyzer, would be able to tell for sure whether the amplifier would work in an acceptable manner on 10 meters in the SSB mode.

K7FE
11-12-2007, 07:41 PM
Quote[/b] (N2RJ @ Nov. 11 2007,17:34)]I think the problem is that these amps are RF keyed, and because they are RF keyed, SSB would make the relay chatter instead of staying "on".
Ryan,
A simple way to hold a relay open a little longer is to use an electrolytic capacitor across the relay coil. The exact value will vary, depending on the relay current draw (it's internal resistance). You could do the algebraic math for the "RC time constant" knowing the lowest voltage that will keep the relay closed. One could even write an equation using calculus, then integrate to determine the work (energy) under the curve, etc............but why?

The easiest way is to just try an electrolytic capacitor across your "unknown" relay and see if the delay time is right for you.

Start with a 47ufd and increase or decrease capacitance as needed. I use a 47ufd, 25V for a 185 ohm 12VDC relay coil.

I additionally added a diode with a Peak Repetitive Reverse Voltage of 600V (or better) like a 1N4005 across the relay coil to prevent the high voltage spike generated by the back EMF of the coil from damaging the relay driver circuit (2N2222 or similar) transistor.

The method without RF control uses the keying voltage from your transceiver to actuate the amplifier's antenna change over relay. The direct keying line method is simpler.

Either way works if designed correctly.

73,
Terry, K7FE

WA7KKP
11-12-2007, 08:12 PM
As per previous posts, the amplifier has to be biased to AB1 or B to amplify AM signals, albeit at very poor efficiency. CW and FM can be amplified using a Class C biased amplifer with no problems.

If it is a tube type amplifier, the only difference for SSB is the addition of a longer time constant for the COR t/r relay. On AM or CW, the relay drops out when the carrier dissapears, resulting in a lot of clatter on CW, and premature failure of the contacts. On SSB, they dropout time (usually determined by a fair sized electrolytic cap) is increased to a couple seconds, so the relay doesn't drop out in between syllables.

If it is solid state, the same thing applies, but be warned that some "CB" amplifiers aren't biased for linear operation -- I have a Palomar TX50 that is zero-biased Class C.

Use of these amplifiers is at your own risk, and I wouldn't fire one up without some sort of bandpass filter or good low-pass filter on the output. Run it gingerly --- you shouldn't get more than 100 watts out under any circumstances, and it should be more like 60-70 watts at most. Like the Swan transceivers, these were grossly overrated to help sell them to the gullible.

Gary WA7KKP

W2VW
11-13-2007, 02:35 AM
If you take that amplifier and add bandpass filters and proper biasing you don't need a bunch of lab equipment to proof it out.

Hams built thousands of amplifiers in the past without use of lab equipment. All it takes is to follow known designs. Not rocket science at all.

K7JEM
11-13-2007, 04:17 AM
Quote[/b] (w2vw @ Nov. 12 2007,19:35)]If you take that amplifier and add bandpass filters and proper biasing you don't need a bunch of lab equipment to proof it out.

Hams built thousands of amplifiers in the past without use of lab equipment. All it takes is to follow known designs. Not rocket science at all.
You can't tell these guys that. If it's ever been associated with CB, it is crap.

Most of these guys have never taken one apart, or looked inside of it to see that many of them just follow the transistor data sheet circuit examples.

Most of these people don't know enough about amps to even comment about the situation.

CB is the bogeyman. Nothing associated with it could ever be good, or usable in an amateur environment.

Joe

WA9SVD
11-13-2007, 05:14 AM
Quote[/b] (K7JEM @ Nov. 12 2007,21:17)]
Quote[/b] (w2vw @ Nov. 12 2007,19:35)]If you take that amplifier and add bandpass filters and proper biasing you don't need a bunch of lab equipment to proof it out.

Hams built thousands of amplifiers in the past without use of lab equipment. All it takes is to follow known designs. Not rocket science at all.
You can't tell these guys that. If it's ever been associated with CB, it is crap.

Most of these guys have never taken one apart, or looked inside of it to see that many of them just follow the transistor data sheet circuit examples.

Most of these people don't know enough about amps to even comment about the situation.

CB is the bogeyman. Nothing associated with it could ever be good, or usable in an amateur environment.

Joe
And even the Motorola Data Sheets (and Application Notes) indicate that output filtering is necessary to ensure their "designs" comply with FCC Technical Standards.
Of course, some people (such as the "CB Amp" manufacturers and some Amateurs) don't worry about such details.

K7JEM
11-13-2007, 05:43 AM
Quote[/b] (wa9svd @ Nov. 12 2007,22:14)]
Quote[/b] (K7JEM @ Nov. 12 2007,21:17)]
Quote[/b] (w2vw @ Nov. 12 2007,19:35)]If you take that amplifier and add bandpass filters and proper biasing you don't need a bunch of lab equipment to proof it out.

Hams built thousands of amplifiers in the past without use of lab equipment. All it takes is to follow known designs. Not rocket science at all.
You can't tell these guys that. If it's ever been associated with CB, it is crap.

Most of these guys have never taken one apart, or looked inside of it to see that many of them just follow the transistor data sheet circuit examples.

Most of these people don't know enough about amps to even comment about the situation.

CB is the bogeyman. Nothing associated with it could ever be good, or usable in an amateur environment.

Joe
And even the Motorola Data Sheets (and Application Notes) indicate that output filtering is necessary to ensure their "designs" comply with FCC Technical Standards.
Of course, some people (such as the "CB Amp" manufacturers and some Amateurs) don't worry about such details.
I think that is what VW is saying.

Too many people here don't want people to get one of these things to play around with, although 95%+ of the components are there and already working.

Some of these require no biasing changes at all, the simple addition of a LPF, or an external BPF is all that may be required.

Hams that want to learn have always experimented with amps and transmitters. Everyone here would probably be encouraging this guy to homebrew an amp, but act like he couldn't possibly fix a CB amp.

Now some of these are probably not very good, but others are well built. A quick look inside to the experienced ham will tell a big story.

The one I have works quite well down to 3.5MHz, but external filtering is required, but that is no big deal.

Joe

N0DRB
01-08-2008, 09:08 AM
I am just a tech, used to have a plus sign http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif , and don't know the answer to how to modify the amp to work on SSB, however it would be nice if all you so called experts would just answer the guy's question. Instead of running off on some other tangents, how about giving some useful info? Maybe he KNOWS it needs filtering, but is trying to tackle one problem at a time.
Your opinions as to whether this amp is junk or not, or whether it will operate within tolerance is irrelevant to the question.

M0DSZ
01-08-2008, 11:59 AM
Some years ago the BBC modified an ancient Marconi SWB18 AM 100kW transmitter for SSB point to point use. It used a pair of water-cooled valves (tubes to you) operated in class C and another pair of valves operated in class AB as the modulator.
Scrapping the modulator and operating the PA stage in a more linear mode reduced the output power to less than a fifth for SSB.
These transmitters obviously had tuned circuits in the drivers and output stages and the harmonic content was very small, no wideband stuff here.

Could this mean your CB amp may well deliver much less than the 250W in the SSB mode with the correct bias? If it's cheap I'd certainly try it (nothing ventured,nothing gained) and would sort out some kind of ALC biassing rather than a fixed bias.

PA5COR
01-08-2008, 12:12 PM
The KL500 can be rebuild for 400 watts linear p.a.

Here's the how to do.

http://home.hetnet.nl/~l.van.lelieveld/inhoud.html
1200 watt transistor amp

http://home.hetnet.nl/~l.van.lelieveld/

Rebuilding the KL500 amp

N0WVA
01-08-2008, 03:04 PM
Ive thought about using one for a homebrew transceiver, always knowing that they would need to be reworked. But it wouldnt be that hard to do. The largest problem with these things is there is no filtering, just broadband transformers going to the antenna jack. It wouldnt be hard to make a decent bandpass filtering for each band and switch them with relays. It could probably put right into the box, and then bolt it to the back of the homebrew rig....Then I would have an Atlas!http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

WA9SVD
01-08-2008, 03:24 PM
Quote[/b] (kc5cmc @ Jan. 08 2008,02:08)]I am just a tech, used to have a plus sign http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif , and don't know the answer to how to modify the amp to work on SSB, however it would be nice if all you so called experts would just answer the guy's question. Instead of running off on some other tangents, how about giving some useful info? Maybe he KNOWS it needs filtering, but is trying to tackle one problem at a time.
Your opinions as to whether this amp is junk or not, or whether it will operate within tolerance is irrelevant to the question.
Actually, we DID answer the gentleman's question, right from the beginning, (That the amp in question can NOT legally be used "as is" for SSB amplification) and described what would be required to modify it for proper use. And without the schematic of the particular amp, it would be very difficult to "design" and draw a schematic for the modifications, not to mention describing the mechanical changes required, which seems to be what you are requesting.

But because the legitimate ANSWERS were not what the fellow WANTED to hear, he took offense.



And ANY project that involves radiating a signal on the Amateur frequencies HAS to comply with FCC technical standards, so that is just as important an aspect as any in an amplifier design or re-design.

WB2WIK
01-08-2008, 04:13 PM
Quote[/b] (N0WVA @ Jan. 08 2008,08:04)]Ive thought about using one for a homebrew transceiver, always knowing that they would need to be reworked. But it wouldnt be that hard to do. The largest problem with these things is there is no filtering, just broadband transformers going to the antenna jack. #It wouldnt be hard to make a decent bandpass filtering for each band and switch them with relays. It could probably put right into the box, and then bolt it to the back of #the homebrew rig....Then I would have an Atlas!http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif
Not quite so easy.

The Palomar, like many inexpensive "CB" amps, not only needs filtering (which you rightly pointed out) but also needs to be linearized, which is not a quick & easy modification.

It isn't biased for linear operation, despite the fact that most were indeed used on "AM." Just on CB, nobody cared. They produced distortion and splatter, and the normal attitude was "so what?" They were being operated illegally anyway, so what does it matter if you fracture a few more regulations along the way?

Amateur radio operators should be above that.

The modifications require to properly bias the Palomar and maintain stability over temperature (which is the biggest challenge with solid state power amplifiers) can be complex and numerous and unless an amateur with expertise in this area has already done it and published his circuit for that specific amplifier, it's also a science experiment: A reiterative process of second, third, fourth, fifth (etc) passes.

WB2WIK/6

W9GB
01-08-2008, 04:24 PM
Quote[/b] ]The reason I asked this question was because I was doing a favor to a radio friend of mine who just got his ticket this Thursday. He has a Yaesu 10 meter rig and wants to find out how to modify the Palomar to work on SSB for 10 meters.
The Palomar amplifier does not have proper transistor BIAS for linear operation (READ Corland's article link provided -- for that education)
OR any output filtering (such as a 5 or 7-pole Chebyshev filter) for "clean" operation.
http://en.wikipedia.org/wiki/Chebyshev_filter

Since many of these were operated mobile -- the "dirty" signal moves around -- in a fixed station operation -- your neighbor will find you -- due to RFI and TVI created.


Quote[/b] ]I am really surprised how fast some of you guys jump the gun and assume that people with lower class licenses are somehow up to no good.
It has nothing to do with a Technician class -- BUT We are providing you with FACTS based on the actual measurements (hard science) -- NOT "marketing hype"; urban legends; "heard on the radio"; "my buddy uses one" and its okay; or faith/beliefs in rumor..

The Palomar sold-state mobile "10-meter" amplifier is a well known illegal amplifer built expressly in 1970s for the CB services.
BTW -- the proliferation of these amplifiers led to the FCC ruling on 25 - 35 MHz amplifiers --- that we have been working to reverse for past 30 years!

Matt, you seem to have a passion or interest in electronics -- why aren't you enrolled at DeVry or some other program to learn more and make more $$ (better career).
LOOK at the G3TSO web page -- this is a properly built 140 watt HF amplifier -- NO it is not a $100 special -- because it has all the necessary components (bias, proper filtering for each band, good heat sink design, etc.).
http://www.qsl.net/g3tso/Homebrew_page2.html


Quote[/b] ]If you aren't aware already, it IS LEGAL to operate SSB between 28.3 to 28.5 MHz -- if you are Technician class licensee. #In fact, I am operating 10 meters already, and I love it.

We are aware. #Glad you are enjoying your privledges and the hobby.

w9gb

KC4UMO
01-08-2008, 04:59 PM
Quote[/b] (w9ass @ Nov. 09 2007,20:08)]His question is, can this amplifier be modified to operate SSB, and if so, how?
To answer the original question,lack of a ssb switch, adding this is simple. These amps use a 2N3904 RF keying circuit. When the transistor is satuated it conducts and closes the relay. A 47mf cap on the emitter of the transistor would hold the relay closed momentary.

Now with that said let may say this.
I read a lot of the post here about this "cb stuff".
Know most people feelings here on it also.
Dont tke it to heart when someones sounds like they are comming on strong about it. There is much you can learn form what they say.

I have already learned a lot of this by doing it myself.
Years ago I tried the texas star and the palamar 200.
Yes got good reports on the air with it. Everyone said it sounded good. Even people that were not on the same frequency that I was on.
This is when I found out what every body meant when they were talking about splatter. Then I had to learn more about had these things worked.

When I got finished with the texas star, it had went from being 2 1/2 inches thick to 4 inches thick. Basicly another box the same size added to the top. And yet it stiff was not perfect.

Making it work on ssb is easy.
Making it work correctly requires a complete rebuild.

Is it worth it?
Only if you are dead serious on learning.

K9STH
01-08-2008, 05:10 PM
CMC:

When one asks a question here on QRZ.com he/she is going to get not only the answer to the question but also the legal perspective on using the particular equipment as well as several different personal opinions.

Since you have only posted one time you are probably pretty new to this site and therefore do not understand the nature of this particular "beast". After participating for a while you will get to know "the usual suspects" in terms of who provides the best information, who provides the worst information, and who just likes to "stir the pot". Since this is the Internet and not actual amateur radio you do have to allow for various interpretations of the situation.

Glen, K9STH
One of the QRZ.com moderators

N0WVA
01-08-2008, 05:56 PM
Quote[/b] (WB2WIK @ Jan. 08 2008,09:13)]
Quote[/b] (N0WVA @ Jan. 08 2008,08:04)]Ive thought about using one for a homebrew transceiver, always knowing that they would need to be reworked. But it wouldnt be that hard to do. The largest problem with these things is there is no filtering, just broadband transformers going to the antenna jack. #It wouldnt be hard to make a decent bandpass filtering for each band and switch them with relays. It could probably put right into the box, and then bolt it to the back of #the homebrew rig....Then I would have an Atlas!http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif
Not quite so easy.

The Palomar, like many inexpensive "CB" amps, not only needs filtering (which you rightly pointed out) but also needs to be linearized, which is not a quick & easy modification.

It isn't biased for linear operation, despite the fact that most were indeed used on "AM." #Just on CB, nobody cared. #They produced distortion and splatter, and the normal attitude was "so what?" #They were being operated illegally anyway, so what does it matter if you fracture a few more regulations along the way?

Amateur radio operators should be above that.

The modifications require to properly bias the Palomar and maintain stability over temperature (which is the biggest challenge with solid state power amplifiers) can be complex and numerous and unless an amateur with expertise in this area has already done it and published his circuit for that specific amplifier, it's also a science experiment: A reiterative process of second, third, fourth, fifth (etc) passes.

WB2WIK/6
Of course.....nobody wants to unleash a nasty signal into the spectrum.

So you float the secondary's center of the input transformer, bypass it to ground, and piddle with the bias voltage at that point....No biggie....Might take a few hours of enjoyable learning, but Im sure I could get it right...... And thats what its all about......right?

But I understand some would just "hook it up" and let it go at that. Definately not a good idea.

WA9CWX
01-08-2008, 11:03 PM
ok..ok...so....tell me if I've got this right....


IF ..... I hook up my 'long quiet' 1923 Ford coil to a wire on one end..and a HUGE Earth ground on the other...I STILL need to filter it...?

What if I JUST use it on 185.7 Khz ?

WA9SVD
01-08-2008, 11:15 PM
Quote[/b] (wa9cwx @ Jan. 08 2008,16:03)]ok..ok...so....tell me if I've got this right....


IF ..... I hook up my 'long quiet' 1923 Ford coil to a wire on one end..and a HUGE Earth ground on the other...I STILL need to filter it...?

What if I JUST use it on 185.7 Khz ?
You might RESONATE the beast at 185.7 kHz, but the BANDWIDTH might be 185.7 MHz! And that REALLY Hertz! http://www.qrz.com/iB_html/non-cgi/emoticons/laugh.gif

w4nti
01-08-2008, 11:48 PM
Quote[/b] (KA9VQF @ Nov. 09 2007,21:07)]While I agree that it is junk and should not be used by any amateur who wants to keep his license, you can remove the cover on the relay that keeps chattering while you try to talk on SSB the take a Popsicle stick and hold the relay down while you talk.

Don’t ask me how I know this will work





{I only did it once I swear.}
Oh good grief,

OR you could add a larger capacitor on the input side of the relay. This will charge up and hold the relay in longer. If you want to get fancy you could add a resistor, a pot if you want, to make it variable.

IF it is linear enough to operate on AM it "SHOULD" be alright on SSB. No guarantee's however. Try it see how many folks threaten to burn you out and you may can get away with it.

I get the impression that some of you believe if a amp is made for CB it is junk. Agreed...a lot of them are. But if one wants to work on it even they can be tamed down.

Not ever being a CBer I don't know what this particular job has in it.

Dan/W4NTI

WB2WIK
01-08-2008, 11:57 PM
Quote[/b] (N0WVA @ Jan. 08 2008,10:56)]Of course.....nobody wants to unleash a nasty signal into the spectrum.

So you float the secondary's center of the input transformer, bypass it to ground, and piddle with the bias voltage at that point....No biggie....Might take a few hours of enjoyable learning, but Im sure I could get it right...... And thats what its all about......right?
Not really.

Doing what you suggest might bias the amplifier properly at, say, room temperature, for one set of drive and load conditions.

But for an amplifier to remain linear over a range of conditions and operating temperatures, applying a regulated bias voltage to the transistor bases won't do that. That's why you see most "properly" biased solid state linear amplifiers have complex networks of biasing components, including ones that continuously compensate for PA device junction temperature.

WB2WIK/6

KA0GKT
01-09-2008, 01:28 AM
OK, Assuming (Yeah, I remember the Ass out of you and me old saw) that the amplifier is spectrally clean (and that is a really big assumption), most amateur rigs have an output to key an external amplifier. CB amplifiers and amps designed for use on the VHF bands often do not, as Amateur VHF rigs rarely have amplifier keying outputs.

The suggestion that a electrolytic capacitor be added to the heying relay is a good one, however, if the exciter (transceiver) in question does have a keying output, it is just as easy to add a key input to the amplifier. The keying output is usually a set of dry contacts (just a contact closure) You neeed to take whatever circuit is used as a COR (Carrier Operated Relay) and bypass it with so that closing a switch will close the relay.

If the amplifier isn't spectrally clean enough to pass muster for operation on the amateur HF bands with the FCC, that can be remedied as well with external filters. Changing the way the amplifier is biased may or may-not be a tough trick depending upon the quality and method of the amplifier's construction.

73 DE KAŘGKT/7

--Steve

N0WVA
01-09-2008, 05:52 AM
Quote[/b] (wa9cwx @ Jan. 08 2008,16:03)]ok..ok...so....tell me if I've got this right.... #


IF ..... I hook up my 'long quiet' 1923 Ford coil to a wire on one end..and a HUGE Earth ground on the other...I STILL need to filter it...?

What if I JUST use it on 185.7 Khz ?
Believe it or not, I actually done that in 6th grade. I remember checking out a library book on radio and it had a crude representation of an early spark rig. When I got home I robbed a coil from one of dads numerous junk cars and got it to spark. My brother showed me how to get a better spark by using a condensor. Then I buried a piece of barn tin for a ground and strung a couple hundred foot of electric fence wire high through the trees. I think I had made a spark gap of some sort and connected the antenna to that. I think I was getting a good quarter mile out of that setup. No one wanted to work the transmitter while I walked through the woods with the receiver!

KE4FES
01-13-2008, 08:04 AM
Quote[/b] (wb7dmx @ Nov. 10 2007,21:23)]sometimes the questions and answers on here are very silly.

until someone can prove me wrong, any ham radio operator can build, modify, any piece of equipment for armature use as long as it conforms to the rules and regulations for the amateur service for the class of liceness one holds

one should have the knowledge and proper test equipment to do this in the proper manner.

as far as I know, there is nothing that can not be used in the amateur service, I have used old surplus military equipment, western union equipment and bell telephone repeaters, commercial Motorola transceivers in my many years of amateur radio.
http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif #YES, WELL SAID !!! and one can add a SIMPLE circuit to provide for SSB MODE. The transmit relay coil is switched by the radio's rf transmit signal ;AMP WAS DESIGNED FOR AM MODE. In ssb mode the modulated signal will have peaks and cut off, thereby the relay will energize and de-energize - "chatter"; WON'T WORK. Selecting an electrlytic polarized cap of correct values in series with a single pole switch APPLIED in parallel with the relay coil will "correct" the chattering when used in ssb mode. The switch allows selection #for ssb mode, and when open allows the relay to operate correctly in the am mode.WHAT HAPPENS; the cap charges when the relay coil [ssb peaked]is energized and discharges into the coil when the ssb cuts off, keeping the relay closed. One can incoporate a "timed control" by adding a suitable potentiometer. WORKS FER ME ! Note; if the relay coil is transistor controlled, you can apply this scheme to the
base [bias] for the same result.

Charlie

WA9SVD
01-13-2008, 02:20 PM
Quote[/b] (KE4FES @ Jan. 13 2008,01:04)]
Quote[/b] (wb7dmx @ Nov. 10 2007,21:23)]sometimes the questions and answers on here are very silly.

until someone can prove me wrong, any ham radio operator can build, modify, any piece of equipment for armature use as long as it conforms to the rules and regulations for the amateur service for the class of liceness one holds

one should have the knowledge and proper test equipment to do this in the proper manner.

as far as I know, there is nothing that can not be used in the amateur service, I have used old surplus military equipment, western union equipment and bell telephone repeaters, commercial Motorola transceivers in my many years of amateur radio.
http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif YES, WELL SAID !!! and one can add a SIMPLE circuit to provide for SSB MODE. The transmit relay coil is switched by the radio's rf transmit signal ;AMP WAS DESIGNED FOR AM MODE. In ssb mode the modulated signal will have peaks and cut off, thereby the relay will energize and de-energize - "chatter"; WON'T WORK. Selecting an electrlytic polarized cap of correct values in series with a single pole switch APPLIED in parallel with the relay coil will "correct" the chattering when used in ssb mode. The switch allows selection for ssb mode, and when open allows the relay to operate correctly in the am mode.WHAT HAPPENS; the cap charges when the relay coil [ssb peaked]is energized and discharges into the coil when the ssb cuts off, keeping the relay closed. One can incoporate a "timed control" by adding a suitable potentiometer. WORKS FER ME ! Note; if the relay coil is transistor controlled, you can apply this scheme to the
base [bias] for the same result.

Charlie
No offense, but you apparently miss the whole point of the entire thread.

It takes a lot more than a switch to keep a relay shut to make an amp operate as a linear amp for "SSB mode."

That is, if it's to follow "good Amateur Practice" and comply with FCC Technical Standards.

But such details don't bother some people.

NA0AA
01-13-2008, 09:03 PM
Quote[/b] (wa9svd @ Jan. 13 2008,07:20)]
Quote[/b] (KE4FES @ Jan. 13 2008,01:04)]
Quote[/b] (wb7dmx @ Nov. 10 2007,21:23)]sometimes the questions and answers on here are very silly.

until someone can prove me wrong, any ham radio operator can build, modify, any piece of equipment for armature use as long as it conforms to the rules and regulations for the amateur service for the class of liceness one holds

one should have the knowledge and proper test equipment to do this in the proper manner.

as far as I know, there is nothing that can not be used in the amateur service, I have used old surplus military equipment, western union equipment and bell telephone repeaters, commercial Motorola transceivers in my many years of amateur radio.
http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif #YES, WELL SAID !!! and one can add a SIMPLE circuit to provide for SSB MODE. The transmit relay coil is switched by the radio's rf transmit signal ;AMP WAS DESIGNED FOR AM MODE. In ssb mode the modulated signal will have peaks and cut off, thereby the relay will energize and de-energize - "chatter"; WON'T WORK. Selecting an electrlytic polarized cap of correct values in series with a single pole switch APPLIED in parallel with the relay coil will "correct" the chattering when used in ssb mode. The switch allows selection #for ssb mode, and when open allows the relay to operate correctly in the am mode.WHAT HAPPENS; the cap charges when the relay coil [ssb peaked]is energized and discharges into the coil when the ssb cuts off, keeping the relay closed. One can incoporate a "timed control" by adding a suitable potentiometer. WORKS FER ME ! Note; if the relay coil is transistor controlled, you can apply this scheme to the
base [bias] for the same result.

Charlie
No offense, but you apparently miss the whole point of the entire thread.

# #It takes a lot more than a switch to keep a relay shut to make an amp operate as a linear amp for "SSB mode."

# #That is, if it's to follow "good Amateur Practice" and comply with FCC Technical Standards.

# #But such details don't bother some people.
I suspect that many responders to this sort of topic take the same thought path that I do:

1. Wow, that's a free amp [but not new they ain't!]
2. CB/10 meter....hmm
3. Well, I could modify it, in which case I'd still have a basically lousy design that would be legal to operate.
4. time/money consideration discussion here.
5. Put item back and decide that if I need an amp, I'll buy an Amateur specific model.

Since going from CB to Amateur allowed me to go immediately from 4/12 watts to 100 watts barefoot 10+ dB, I'm just not that watt-hungry currently - still learning what that 100 can do.

I suppose that if you want to modify an old CB amp because it would be fun for you to figure it out, that's cool but I'd rather spend time/money on something else myself.

WA9SVD
01-13-2008, 10:12 PM
Quote[/b] (KG6WOU @ Jan. 13 2008,14:03)]
Quote[/b] (wa9svd @ Jan. 13 2008,07:20)]
Quote[/b] (KE4FES @ Jan. 13 2008,01:04)]
Quote[/b] (wb7dmx @ Nov. 10 2007,21:23)]sometimes the questions and answers on here are very silly.

until someone can prove me wrong, any ham radio operator can build, modify, any piece of equipment for armature use as long as it conforms to the rules and regulations for the amateur service for the class of liceness one holds

one should have the knowledge and proper test equipment to do this in the proper manner.

as far as I know, there is nothing that can not be used in the amateur service, I have used old surplus military equipment, western union equipment and bell telephone repeaters, commercial Motorola transceivers in my many years of amateur radio.
http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif YES, WELL SAID !!! and one can add a SIMPLE circuit to provide for SSB MODE. The transmit relay coil is switched by the radio's rf transmit signal ;AMP WAS DESIGNED FOR AM MODE. In ssb mode the modulated signal will have peaks and cut off, thereby the relay will energize and de-energize - "chatter"; WON'T WORK. Selecting an electrlytic polarized cap of correct values in series with a single pole switch APPLIED in parallel with the relay coil will "correct" the chattering when used in ssb mode. The switch allows selection for ssb mode, and when open allows the relay to operate correctly in the am mode.WHAT HAPPENS; the cap charges when the relay coil [ssb peaked]is energized and discharges into the coil when the ssb cuts off, keeping the relay closed. One can incoporate a "timed control" by adding a suitable potentiometer. WORKS FER ME ! Note; if the relay coil is transistor controlled, you can apply this scheme to the
base [bias] for the same result.

Charlie
No offense, but you apparently miss the whole point of the entire thread.

It takes a lot more than a switch to keep a relay shut to make an amp operate as a linear amp for "SSB mode."

That is, if it's to follow "good Amateur Practice" and comply with FCC Technical Standards.

But such details don't bother some people.
I suspect that many responders to this sort of topic take the same thought path that I do:

1. Wow, that's a free amp [but not new they ain't!]
2. CB/10 meter....hmm
3. Well, I could modify it, in which case I'd still have a basically lousy design that would be legal to operate.
4. time/money consideration discussion here.
5. Put item back and decide that if I need an amp, I'll buy an Amateur specific model.

Since going from CB to Amateur allowed me to go immediately from 4/12 watts to 100 watts barefoot 10+ dB, I'm just not that watt-hungry currently - still learning what that 100 can do.

I suppose that if you want to modify an old CB amp because it would be fun for you to figure it out, that's cool but I'd rather spend time/money on something else myself.
Again, with all due respect, I fear you also miss the point. there is MORE to making a "CB" amp (such as the Palomar originally described) work on SSB in addition to making a relay remained closed during SSB transmit. Many, if not most of such amps are NOT capable of LINEAR amplification as designed, and modification is not a simple matter of adding a switch.

NA0AA
01-14-2008, 02:33 AM
Quote[/b] (wa9svd @ Jan. 13 2008,15:12)][quote=KG6WOU,Jan. 13 2008,14:03]Again, with all due respect, I fear you also miss the point. #there is MORE to making a "CB" amp (such as the Palomar originally described) work on SSB in addition to making a relay remained closed during SSB transmit. #Many, if not most #of such amps are NOT capable of LINEAR amplification as designed, and modification is not a simple matter of adding a switch.
Actually, I sort of think I got the point here.

1st off, I personally would not waste my time/money on any such project - IMHO, it would be more profitable to start from scratch than modify someone else's mistakes.

But I DID assume that 'making it legal' included doing whatever it took to make it pass spectral purity requirements, not sticking a popsickle stick into the flipping relay.

I think it's a waste of time and money to modify a CB amp.

WA9SVD
01-14-2008, 04:26 AM
Quote[/b] (KG6WOU @ Jan. 13 2008,19:33)]
Quote[/b] (wa9svd @ Jan. 13 2008,15:12)][quote=KG6WOU,Jan. 13 2008,14:03]Again, with all due respect, I fear you also miss the point. there is MORE to making a "CB" amp (such as the Palomar originally described) work on SSB in addition to making a relay remained closed during SSB transmit. Many, if not most of such amps are NOT capable of LINEAR amplification as designed, and modification is not a simple matter of adding a switch.
Actually, I sort of think I got the point here.

1st off, I personally would not waste my time/money on any such project - IMHO, it would be more profitable to start from scratch than modify someone else's mistakes.

But I DID assume that 'making it legal' included doing whatever it took to make it pass spectral purity requirements, not sticking a popsickle stick into the flipping relay.

I think it's a waste of time and money to modify a CB amp.
maybe I didn't understand what you implied above.

A waste of time? probably. A lot of time to PROPERLY modify such an amp? Probably If it's for a learning experience, it might be OK, if one has access to the proper instruments to ensure it conforms with at least Amateur technical standards. Easy? Probably not. Just designing the filters will take a bit of time; modifying the filter values to accomodate "real world" values of L and C can take many more hours. And the filter components will need to be switched to be effective; so that negates use of the original case for a multiband design.

Probably not worth the time/money as you say; parts are probably worth more than the amp as a whole. (Then again, that's really the case with trying to adapt any single band amp to multi-band use.)

KE4FES
01-14-2008, 04:52 AM
Quote[/b] (wa9svd @ Jan. 13 2008,07:20)]
Quote[/b] (KE4FES @ Jan. 13 2008,01:04)]
Quote[/b] (wb7dmx @ Nov. 10 2007,21:23)]sometimes the questions and answers on here are very silly.

until someone can prove me wrong, any ham radio operator can build, modify, any piece of equipment for armature use as long as it conforms to the rules and regulations for the amateur service for the class of liceness one holds

one should have the knowledge and proper test equipment to do this in the proper manner.

as far as I know, there is nothing that can not be used in the amateur service, I have used old surplus military equipment, western union equipment and bell telephone repeaters, commercial Motorola transceivers in my many years of amateur radio.
http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif #YES, WELL SAID !!! and one can add a SIMPLE circuit to provide for SSB MODE. The transmit relay coil is switched by the radio's rf transmit signal ;AMP WAS DESIGNED FOR AM MODE. In ssb mode the modulated signal will have peaks and cut off, thereby the relay will energize and de-energize - "chatter"; WON'T WORK. Selecting an electrlytic polarized cap of correct values in series with a single pole switch APPLIED in parallel with the relay coil will "correct" the chattering when used in ssb mode. The switch allows selection #for ssb mode, and when open allows the relay to operate correctly in the am mode.WHAT HAPPENS; the cap charges when the relay coil [ssb peaked]is energized and discharges into the coil when the ssb cuts off, keeping the relay closed. One can incoporate a "timed control" by adding a suitable potentiometer. WORKS FER ME ! Note; if the relay coil is transistor controlled, you can apply this scheme to the
base [bias] for the same result.

Charlie
No offense, but you apparently miss the whole point of the entire thread.

# #It takes a lot more than a switch to keep a relay shut to make an amp operate as a linear amp for "SSB mode."

# #That is, if it's to follow "good Amateur Practice" and comply with FCC Technical Standards.

# #But such details don't bother some people.
http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif SVD: MDX's post covered it ! My "appendage post" merely described the relay operation / function modification. Did not advocate usage , only "how to" !
I fully agree with MDX's POST ! I THINK THIS COVERS "IT" ?? IF SOMETHING IS MISSING; YOU "HUNT" FOR IT....................

Charlie

WA9SVD
01-14-2008, 05:53 AM
Quote[/b] (KE4FES @ Jan. 13 2008,21:52)]http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif YES, WELL SAID !!! and one can add a SIMPLE circuit to provide for SSB MODE. The transmit relay coil is switched by the radio's rf transmit signal ;AMP WAS DESIGNED FOR AM MODE. In ssb mode the modulated signal will have peaks and cut off, thereby the relay will energize and de-energize - "chatter"; WON'T WORK. Selecting an electrlytic polarized cap of correct values in series with a single pole switch APPLIED in parallel with the relay coil will "correct" the chattering when used in ssb mode. The switch allows selection for ssb mode, and when open allows the relay to operate correctly in the am mode.WHAT HAPPENS; the cap charges when the relay coil [ssb peaked]is energized and discharges into the coil when the ssb cuts off, keeping the relay closed. One can incoporate a "timed control" by adding a suitable potentiometer. WORKS FER ME ! Note; if the relay coil is transistor controlled, you can apply this scheme to the
base [bias] for the same result.

Charlie
No offense, but you apparently miss the whole point of the entire thread.

It takes a lot more than a switch to keep a relay shut to make an amp operate as a linear amp for "SSB mode."

That is, if it's to follow "good Amateur Practice" and comply with FCC Technical Standards.

But such details don't bother some people.[/quote]
http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif SVD: MDX's post covered it ! My "appendage post" merely described the relay operation / function modification. Did not advocate usage , only "how to" !
I fully agree with MDX's POST ! I THINK THIS COVERS "IT" ?? IF SOMETHING IS MISSING; YOU "HUNT" FOR IT....................

Charlie[/QUOTE]
OK, but my point (and that of others) was that the amp in question (and many others like it,) while "claiming" to be for "AM" amplification, do NOT operate in a linear mode or a linear class of operation, (A, AB or B) and the simple addition of a switch could be misinterpreted by many as the ONLY modification needed to make such an amp operate as an amplifier for SSB.

KE4FES
01-18-2008, 06:43 AM
Quote[/b] (WA9SVD @ Jan. 13 2008,22:53)]
Quote[/b] (KE4FES @ Jan. 13 2008,21:52)]http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif #YES, WELL SAID !!! and one can add a SIMPLE circuit to provide for SSB MODE. The transmit relay coil is switched by the radio's rf transmit signal ;AMP WAS DESIGNED FOR AM MODE. In ssb mode the modulated signal will have peaks and cut off, thereby the relay will energize and de-energize - "chatter"; WON'T WORK. Selecting an electrlytic polarized cap of correct values in series with a single pole switch APPLIED in parallel with the relay coil will "correct" the chattering when used in ssb mode. The switch allows selection #for ssb mode, and when open allows the relay to operate correctly in the am mode.WHAT HAPPENS; the cap charges when the relay coil [ssb peaked]is energized and discharges into the coil when the ssb cuts off, keeping the relay closed. One can incoporate a "timed control" by adding a suitable potentiometer. WORKS FER ME ! Note; if the relay coil is transistor controlled, you can apply this scheme to the
base [bias] for the same result.

Charlie
No offense, but you apparently miss the whole point of the entire thread.

# #It takes a lot more than a switch to keep a relay shut to make an amp operate as a linear amp for "SSB mode."

# #That is, if it's to follow "good Amateur Practice" and comply with FCC Technical Standards.

# #But such details don't bother some people.
http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif SVD: #MDX's post covered it ! My "appendage post" merely described the relay operation / function modification. Did not advocate usage , only "how to" !
#I fully agree with MDX's POST ! I THINK THIS COVERS "IT" ?? IF SOMETHING IS MISSING; YOU "HUNT" FOR IT....................

Charlie[/quote]
OK, but my point (and that of others) was that the amp in question (and many others like it,) while "claiming" to be for "AM" amplification, do NOT operate in a linear mode or a linear class of operation, (A, AB or B) and the simple addition of a switch could be misinterpreted by many as the ONLY modification needed to make such an amp operate as an amplifier for SSB.[/quote]
http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif # etc ,etc ,etc............... if they are not aware of the postings #ALL READY RELATED to that , DON'T WORRY. They probably are to dumb to understand and follow my discription of the RELAY circuit , WHICH #was "attached " to #a very explicit statement #directed to the very subject OF YOUR CONTENTION. I NEVER MISSED THE THREAD NOR DID I DIRECT THE POSTER HOW TO OR NOT TO USE HIS EQUIPMENT-- OTHERS DID THAT ,very well..
MY POST WAS TECHNICAL , NOT "MORAL".
# # I'm#giving my horse a rest, suggest you do the same
before it drops from exhaustion.

Charlie

W2VW
01-19-2008, 01:26 AM
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