PDA

View Full Version : Converting CB to 10 meters



KG4YUV
02-20-2005, 01:54 AM
I'm interested in converting a CB to 10 meters as a fun project. Is there any straight forward de facto way of doing it or is it different for each rig?

WJ5O
02-20-2005, 02:47 AM
Hi Patrick,
Congratulations on Your up grade to Extra Class today........ OK, if You enjoy "fun" projects in regard to converting a CB into the 10 meter band ...... How about operating a ten meter propagation beacon fashioned from a converted CB.... as a previous post indicated.... almost each CB is different but, there is a group of the older 23 channel CBs that use an 14/23 IF mix that are generally alike.... and almost any electronically inclined person can make the conversion to a frequency within the ten meter beacon band. #Take a look at the step by step conversion process at:CB 2 ten meters (http://www.qsl.net/wj5o/cb2bcn.htm)
The North Georgia area can always use another propagation beacon.... especially now that cycle 23 is "pushing" for a low. http://www.qrz.com/iB_html/non-cgi/emoticons/rock.gif

K8YS
02-20-2005, 03:23 AM
there is a ton of info out there. The first thing I would do is to go buy borrow or otherwise aquire a couple of books by Lou Franklin of CB City International - www.cbcintl.com. One is called the "Screwdrivers Expert" and the other is a PLL Databook.

"73 Magazine" had a lot of articles on converting CB to 10 in the late 70's early 80's too.

The easiest way is to take the 12MHz reference crystal and buy a new crystal for the new band. Remember that the xtal is a 3rd overtone, so if you want to move up 1MHz, add 333.333kHz to the xtal freq and order that. You may also consider at this point if you want the center channel on the 5kHz or on the 0kHz (28.405 vs 28.400) and build this into the reference xtal. You can also add a second xtal and put it on the useless PA speaker switch. You can have one that puts the center channel on the 405 and one that put the center on 400.

Buy quality xtals, International Crystal. They will help you to get the correct cut and load.

There are other mods, such as making the clarifier work on transmit as a VXO, you can also add a vernier dial.

I've modified HyGain, EF Johnsons and Cobra (my favorite for ease of modification) to 10 meters.

KC0KBH
02-20-2005, 03:46 PM
I would do the beacon.

WJ5O
02-20-2005, 06:25 PM
For KC0KBH......... Most of the ten meter Ops would appreciate another propagation beacon in MN......... It's nice to see another beacon enthusists' in Northern USA. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

KC0KBH
02-21-2005, 02:56 AM
Ok. I have a 10m antenna, I will try to get one up b summer.

KG4YUV
02-21-2005, 03:10 PM
I have a Cobra 19 DX, two others that I'll have to check on (don't quite remember what they are), and two handheld Realistics.

KC0KBH
02-21-2005, 06:39 PM
You need to get the older SSB 23 channel ones. Those 40 channel ones with a PLL only have 1 crystal. With the 23 channel ones, swapping some of the x-tals will work.

KG4YUV
02-21-2005, 10:19 PM
I'm not as inclined in electronis yet as I should be. I'm liking the beacon idea. First off, what exactly is an XTAL? I'm guessing it's not short for crystal, but I may be wrong. I have a 23 channel radio, but it's AM. I'll be looking into obtaining a Cobra 148 in the future, since they're easy according to ANQ.

K8YS
02-21-2005, 10:25 PM
Quote[/b] (KG4YUV @ Feb. 21 2005,17:19)]I'm not as inclined in electronis yet as I should be. I'm liking the beacon idea. First off, what exactly is an XTAL? I'm guessing it's not short for crystal, but I may be wrong. I have a 23 channel radio, but it's AM. I'll be looking into obtaining a Cobra 148 in the future, since they're easy according to ANQ.
XTAL = crystal

If you want to build a beacon, I'd use a crystal controlled 3 or 6 channel AM CB and then build a timer/keyer.

I would not waste my time or money trying to convert a 23 channel anything. They we not normally PLL, but rather used a combo of high and low crystals to mix and the product was 27MHz.

That means, instead of ONE XTAL, you need to replace 4.

Since good quality crystals are expensive, you will soon have $100 tied up in a radio that could be replaced for $35.00.

VK4XJB
02-22-2005, 12:42 AM
Quote[/b] (KC0KBH @ Feb. 22 2005,04:39)]You need to get the older SSB 23 channel ones. #Those 40 channel ones with a PLL only have 1 crystal. #With the 23 channel ones, swapping some of the x-tals will work.

Pick your pll radio. The radio I converted to 10m is based on a pll02a. As far as moving the radio from 11m to 10m all I had to do was change the state of one of the programing pins on the pll chip. Cutting 1 track to change the state of that 1 pin was quicker and cheaper than trying to buy a suitable crystal. There are other pll chips that are just as easy to to change how they are programmed.

WJ5O
02-22-2005, 01:39 AM
QUOTE from above......K8YS..... I would not waste my time or money trying to convert a 23 channel anything. They we not normally PLL, but rather used a combo of high and low crystals to mix and the product was 27MHz.

That means, instead of ONE XTAL, you need to replace 4.

Since good quality crystals are expensive, you will soon have $100 tied up in a radio that could be replaced for $35.00
**********************************************

Well, I purchased two old CBs at a garage sale....... for $3.00... One was an old 23 channel rig with an IF mixing scheme of 14/23 MHz... The other was a 40 channel CB with a reference crystal of 10.240 MHz..... Substitute the 10.240MHz crystal for the 11.275MHz transmit oscillator crystal in the 23 channel rig.. Now, channel 1 becomes a transmit frequency of 28.000MHz. .
Channel 10 becomes 28.110MHz.
Channel 19 becomes 28.220MHz
Channel 20 becomes 28.240MHz
Channel 21 28.250MHz
Channel 22 28.260MHz
Channel 23 28.290MHz
Now channels 19 through 23 are in the beacon frequency range on ten meters........

Yes, crystals are getting expensive ...... if a person orders them.... but, if retrieved from another CB they certainly are more economical. # http://www.qrz.com/iB_html/non-cgi/emoticons/rock.gif

KC0KBH
02-22-2005, 01:44 AM
Yes, that is what I did. I will get a little more stable, less used CB off ebay and use that for a beacon.

KG4YUV
02-22-2005, 04:45 AM
WJ50,

I reopened my Cobra 19DX 40 channel PLL radio today and I found the 10.240 XTAL, it was suprisingly enough to me clearly marked. Here's what I'm getting from you:

If I take the 11.275 XTAL out of a 23 channel radio and put the 10.240 XTAL from my Cobra or another 40 CH PLL radio in its place, I'll have a 10 meter channelized radio that I can put a beacon controller on??

But in order to be a CW beacon it would have to be a SSB radio, right? And if it's AM then I'll have a 10 meter AM transmitter?

KC0NBW
02-22-2005, 06:07 AM
Quote[/b] (KC0KBH @ Feb. 21 2005,18:44)]Yes, that is what I did. #I will get a little more stable, less used CB off ebay and use that for a beacon.
why pay premium price for a cb on ebay?

if you ask around your area, you might find someone willing to give you one, or, you might find one for little or nothing at st. cloud this weekend.

i bought a fully functional uniden pc55 40 channel for $2
at a thrift store in the cities so i could try to determine the origins of a strong rf signal that was knocking the computer off the phone line here.

i found the source and convinced the guy that if he did not stop using his amplifier, i would turn him into the fcc !

i never did tell him i am a ham, he would probably just have kept on using the amp ! http://www.qrz.com/iB_html/non-cgi/emoticons/laugh.gif

KC0NBW
02-22-2005, 06:15 AM
Quote[/b] (KG4YUV @ Feb. 21 2005,21:45)]But in order to be a CW beacon it would have to be a SSB radio, right? And if it's AM then I'll have a 10 meter AM transmitter?
a ssb radio has no carrier, no carrier essentially means no cw !

an am radio with no audio input just transmits a dead carrier. keying that carrier on and off in morse code makes a great cw transmitter !

remember, a beacon does not have to receive ! http://www.qrz.com/iB_html/non-cgi/emoticons/cool.gif http://www.qrz.com/iB_html/non-cgi/emoticons/laugh.gif

mcjim555
02-22-2005, 01:27 PM
KC4YUG, if you need a 10.240 XTAL I have a couple, e-mail me w/your snail-mail address and I will send it to you. mcjim555@yahoo.com http://www.qrz.com/iB_html/non-cgi/emoticons/laugh.gif

KG4YUV
02-22-2005, 01:29 PM
Quote[/b] (KC0NBW @ Feb. 22 2005,02:15)]
Quote[/b] (KG4YUV @ Feb. 21 2005,21:45)]But in order to be a CW beacon it would have to be a SSB radio, right? And if it's AM then I'll have a 10 meter AM transmitter?
a ssb radio has no carrier, no carrier essentially means no cw !

an am radio with no audio input just transmits a dead carrier. keying that carrier on and off in morse code makes a great cw transmitter !

remember, a beacon does not have to receive ! http://www.qrz.com/iB_html/non-cgi/emoticons/cool.gif #http://www.qrz.com/iB_html/non-cgi/emoticons/laugh.gif
So then all I need is the AM 23 channel radio, correct? And I just need some kind of interface to connect a keyer to its mic input to key the carrier on and off, but nothing going to the audio pin, right?

KG4YUV
02-22-2005, 06:56 PM
I'm going to be looking around for a 23 ch radio with the 11.275 mhz xtal in it to replace.

KC0NBW
02-22-2005, 09:34 PM
Quote[/b] (KG4YUV @ Feb. 22 2005,06:29)]
Quote[/b] (KC0NBW @ Feb. 22 2005,02:15)]
Quote[/b] (KG4YUV @ Feb. 21 2005,21:45)]But in order to be a CW beacon it would have to be a SSB radio, right? And if it's AM then I'll have a 10 meter AM transmitter?
a ssb radio has no carrier, no carrier essentially means no cw !

an am radio with no audio input just transmits a dead carrier. keying that carrier on and off in morse code makes a great cw transmitter !

remember, a beacon does not have to receive ! http://www.qrz.com/iB_html/non-cgi/emoticons/cool.gif #http://www.qrz.com/iB_html/non-cgi/emoticons/laugh.gif
So then all I need is the AM 23 channel radio, correct? And I just need some kind of interface to connect a keyer to its mic input to key the carrier on and off, but nothing going to the audio pin, right?
a better way would be to wire the ptt so it is in transmit all the time and key the final on and off .

that way, the oscillator is up and running steady and more likely to give you a clean , chirpless signal !

then cut the power to everything between transmissions.
http://www.qrz.com/iB_html/non-cgi/emoticons/cool.gif

WJ5O
02-23-2005, 01:57 AM
NBW I maintain a listing of equipment used by 79 of the approx 190 worldwide ten meter propagation beacons...... 21 of these beacon operators use converted CBs...... I only know of one beacon that currently uses the method that You have described.......... (a New Hampshire beacon) ...... I monitor the beacon band on a daily basis and the New Hampshire beacon sounds no better or no worse than any of the other converted CB beacon rigs.
I've been operating a ten meter beacon for almost 13 years in which the PTT circuit is keyed........ I will admit however, that the first rig I used for eleven years before it "smoked"... That I had to put a capacitor & resistor across the PTT circuit to prevent "key clicks". This latest rig has no such problem as "key clicks" and my keying interface "pulls" the PTT circuit to ground to key the rig message........ and this is a 24/7 operation ......
My approach to beacon operation is to keep it simple........ It's certainly simple just to have the keying interface go directly to the rig via the mic connector. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

WA7KKP
03-04-2005, 06:36 PM
Well, conversion of CB to 10 depends on the radio:

AM vs. SSB? PLL or xtal synthesis (old 23 channel radios)

Many AM radios used the same xtal synthesis scheme; it is best to find a Sams CB series book on the radio first for the particular details. Then you have to decide where to convert it to -- most AM is toward the top end of the 28.5 to 29 MHz segment and there is no standardized frequencies/band plan. A VFO would probably be needed.

I'd stick to SSB with modifiable PLL chips as mentioned previously. All 40 channel radios were PLL, and a handful of 23 channel PLL's were built just before the changeover (FCC type acceptance was okayed -- and most times only the switch was replaced to make a 40 channel radio)

With a PLL, you can change ONE crystal to move the radio, and hack into the circuitry to bring out more control lines to get more "channels". This is exactly what many freebander CB types do. CBC International has kits and information on most of the common modifiable PLL's available and what radios use what PLL and where.

Caveat: most radios built in the recent past have been engineered to be UNMODIFIABLE or had epoxy smeared over the PLL chip to prevent hacking. Avoid these.

This would be a good experience for someone with a modicum of radio service experience, definitely not for a newbie!! But if you keep your expenses low, and be careful, this is a great learning experience!

Gary WA7KKP

W0LC
03-04-2005, 06:59 PM
You might drop KB5LF as he has plans on how to convert a CB to 6 meters as well. Something equally fun to have available!


Specifically:

From February 1985 73 Magazine pages 22 - 28.
James L. Patterson KB5LF
3514 N. Cleveland
Enid, OK 73703
(580) 242- 4287




GL!

KC0NBW
03-04-2005, 07:00 PM
Quote[/b] (wj5o @ Feb. 22 2005,18:57)]NBW # # # I maintain a listing of equipment used by 79 of the approx 190 worldwide ten meter propagation beacons...... 21 of these beacon operators use converted CBs...... I only know of one beacon that currently uses the method that You have described.......... (a New Hampshire beacon) ...... I monitor the beacon band on a daily basis and the New Hampshire beacon sounds no better or no worse than any of the other converted CB beacon rigs.
I've been operating a ten meter beacon for almost 13 years in which the PTT circuit is keyed........ I will admit however, that the first rig I used for eleven years before it "smoked"... That I had to put a capacitor & resistor across the PTT circuit to prevent "key clicks". #This latest rig has no such problem as "key clicks" and my keying interface "pulls" the PTT circuit to ground to key the rig message........ and this is a 24/7 #operation ......
My approach to beacon operation is to keep it simple........ It's certainly simple just to have the keying interface go directly to the rig via the mic connector. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif
it all depends on the radio !

having the oscillator up and running and keying the final is more likely to give you a clean signal regardless of what brand radio you are using . http://www.qrz.com/iB_html/non-cgi/emoticons/cool.gif

KC0NBW
03-04-2005, 07:03 PM
Quote[/b] (W0LC @ Mar. 04 2005,11:59)]You might drop KB5LF as he has plans on how to convert a CB to 6 meters as well. #Something equally fun to have available!


Specifically:

From February 1985 73 Magazine pages 22 - 28.
James L. Patterson KB5LF
3514 N. Cleveland
Enid, OK 73703
(580) 242- 4287




GL!
i did convert a heathkit xtal type cb to 6 meters way back !

unfortunately i could not afford the crystals to get it on a freq that was used locally, so it went into the parts bin ! http://www.qrz.com/iB_html/non-cgi/emoticons/laugh.gif

K8YS
03-05-2005, 05:32 AM
Quote[/b] (KC0NBW @ Feb. 22 2005,16:34)]a better way would be to wire the ptt so it is in transmit all the time and key the final on and off .

that way, the oscillator is up and running steady and more likely to give you a clean , chirpless signal !

then cut the power to everything between transmissions.
http://www.qrz.com/iB_html/non-cgi/emoticons/cool.gif
the same way you "key" a repeater transmitter.

WA2ZDY
03-05-2005, 03:10 PM
Quote[/b] (K8YS @ Mar. 05 2005,01:32)]the same way you "key" a repeater transmitter.
Except that with a repeater, chirp is a non-issue. If you've ever tuned a repeater subband with a SSB/CW receiver, you know that repeaters nearly all have chirp on keyup. Again, operationally it doesn't matter.

On CW it matters a WHOLE lot! Chirp and key clicks on CW are not in keeping with good engineering practice and would likely result in an OO notice if not a pink ticket from FCC.

W4ITJ
03-05-2005, 07:53 PM
Check "73 Magazine" of 20 to 25 years back. I may have a few of them (can look for you if necessary) as I was gonna do the same thing, but never go to it - other than to buy up about 3 or 4 of the 10 meter boards.

Doc, W4ITJ

KC0NBW
03-05-2005, 08:24 PM
Quote[/b] (W4ITJ @ Mar. 05 2005,12:53)]Check "73 Magazine" of 20 to 25 years back. #I may have a few of them (can look for you if necessary) as I was gonna do the same thing, but never go to it - other than to buy up about 3 or 4 of the 10 meter boards.

Doc, W4ITJ
those articles were about convertin them for phone use.
the discussion here has turned to using them for cw beacons.

ad: Waters-2