AMP Elmer help needed for a Maverick 250

Discussion in 'Amateur Radio Amplifiers' started by KJ4ZIZ, Jun 14, 2011.

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  1. KJ4ZIZ

    KJ4ZIZ Ham Member QRZ Page

    Hi, I have a D&A Manufacture Maverick 250 amp. I think this is a multi mode as it has a switch for 40, 20 and 15 meters on the front.
    I do not have a manual and have never run an amp before. The tubes are 4 6me6 and I have no idea what the drive is or the output.
    I was told the amp will do 750w on ssb is this right. There are 4 other tubes and the only number/letters I find is, AJ help?

    I would like to hook this up to a Kenwood TS-520s. Do I need anything special to hook it to the radio? I am asking cause I don't know.
    All this amp stuff is new to me.

    If anyone has a manual and can make me a copy and send it via mail or email let me know...Any and all other info about this amp would
    be very helpful to me.

    Thanks Elmers for your help.

    Richard KJ4ZIZ
  2. KA9UCN

    KA9UCN Ham Member QRZ Page

    The D&A 250 is an old CB amp that used the 4 smaller tubes to drive the 4 sweep tubes. (5 watts drive) it is not usable for anything other than causing problems and you do not want it associated with you or ham radio.
    The ts 520 will over drive it to the point of total destruction. Best advice is throw it in the parts pile.
  3. KF6ABU

    KF6ABU Ham Member QRZ Page

  4. WG7X

    WG7X Ham Member QRZ Page






    Guess how many times this question is going to be asked in the next year and win a free subscription to "S-9" magazine!

    Yes, gonna be a good contest!


  5. KA9UCN

    KA9UCN Ham Member QRZ Page

    I guess 19
  6. W0BTU

    W0BTU Ham Member QRZ Page

    I agree. That amplifier should never, ever be used, period. Not even on the ham bands.

    The sweep tubes in that amp are worth a king's ransom. Sell them, and buy a real linear.
  7. KF6ABU

    KF6ABU Ham Member QRZ Page

    over/under on it being used anyways?
  8. K9STH

    K9STH Ham Member QRZ Page


    The bandswitch on the front of the "linear" (I say "linear" because the units is no where being linear) was an attempt by many of the illegal "CB" amplifier manufacturers to get around the ban on selling such equipment. There is absolutely no way that the equipment is going to even try to work anywhere except around 27 MHz. The output is dirty, definitely not linear, etc. The tubes were cheap when the unit was originally sold but today are very expensive. I would sell the tubes and then "part out" the actual unit. There will be some parts that are usable for other projects.

    Glen, K9STH
  9. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I think this is a great suggestion. If the tubes are good (can't tell by just looking at them), the tubes are worth more than the amplifier. I'd "part it out," put the tubes on eBay (if you know they're good), use the money to buy something else.
  10. W9GB

    W9GB Ham Member QRZ Page

    Nope. This is a well known illegal CB amplifier that used TV sweep tubes (1960s/1970s). TV Sweep tubes have not been manufacutred in USA or Europe since 1980 !
    The ONLY sweep tube (EL509/EL519) still produced is in Eastern Europe for older old Soviet bloc countries (for their old TVs).
    This glass sweep tube tube will not be manufactured many more years.

    Unsuitable for your Kenwood TS-520. These units only required 5 watts drive (cheap CB radio < $100) ... luck to get 250 to 300 watts output - on new tubes.
    Your Kenwood TS-520 already provides a solid 100 to 120 watts RF output .... doubling RF power output is ONLY 3 dB increase (you are suppose to KNOW that as part of your
    PCC licnese study) ... you could upgrade your coax and antenna and get 3 dB improvement !!

    NOPE, CB urban legend.

    BAD IDEA. Here you have a quality Japanese HF radio from 1970s that used 6146 RF tubes (better than those sweep tubes).

    New radio amateurs, like yourself, -- need to get better educated BEFORE spending $$ (that many are hard pressed to get) and using/hooking up HF amplifiers.

    You can ALWAYS -- ASK HERE -- (or read reviews on -- BEFORE you make a purchase with your hard earned $$$.

    This was NOT a "bargain" the seller may have told you -- he is very HAPPY to have your money $$.

    ELMER ADVICE: Sell the Sweep tubes for $$$, part out the rest with your local scrap metal dealer for a few $$.

    I see you have plenty of other radios (QRZ profile) .. so take some $$ and buy a Quality used or new HF amplifier (or sell some of your other radios).
    The Heathkit SB-200 or SB-220 are a good used ampliifer purchase -- given your DIY builder background.
    Find one and restore it -- the Heathkit Construction manuals are available to GUIDE you.

    Last edited: Jun 14, 2011
  11. KM3F

    KM3F Ham Member QRZ Page

    Hi Richard, Sorry the replies to you inquirey seem a bit harsh.
    Maybe you are new to HF and have not learned about such things yet.
    The unit you got is not suitable for amateur use.
    If you check the rules you will come to find out the emission standards and rules cannot be met by such a unit.
    This is what is basicly being referred to.
    I would not even let a CBer have it once you got it.
    Better to keep for a project latter after you get to know what you can do with the parts.
    The power tubes are not RF grade for good linearity as well as litle or no filtering in the input and output.

    Best you might do sometime is gut it except for the power supply and pick a couple tubes that are used in amateur service at the voltage and current the supply is able to provide and rebuild it. Then you might get a couple hundred watts out +/-.
    But, that power level is not enough to make a worthwhile boost in your signal from the Kenwood but maybe from a QRP rig.
    To get a feel for this, suppose for example the power supply were to run at 900 volts dc and the current was 300 milliamp, that would be 270 watts input minus the efficiency of about 60%. That leaves you with only about 162 watts into the antenna. If you figure the power difference in DB between your Kenwood output power at about 100 watts and the amplifier, the difference could not even be noticed at the recieving end of a QSO.
    Hope you understand the situation. All those formulas, items and rules you studied to get your ticket come into play here.
    It's all part of learning.
    Good luck.
    Last edited: Jun 15, 2011
  12. KJ4ZIZ

    KJ4ZIZ Ham Member QRZ Page

    Hi all who have replied. Yes I am fairly new to the ham world and was looking for a SB200 but when I came upon this amp
    I knew the tubes were worth some $$$ so I got it. Now an older ham told me I could use it with the Icom 706 with 5 watts drive.

    All the tubes work and the amp is in very good working condition. The price was right and as some of you have said with some
    more learning I may be able to make an amp for the HF band out of the parts. It has 2 transformers and a fan and a nice case
    so I can probably do something with it...Any ideas on building something that will do 600 watts???

    Thanks for all the replies, especially the ones with good ideas and comments...As for the others well instead of ragging on me share
    some of your knowledge and help out a new guy.
  13. W8JI

    W8JI Ham Member QRZ Page


    Unless you have run the amplifier, you have absolutely no idea if the sweep tubes are good or not. Because the tubes "light up" does not mean they are good. As a matter of fact nearly all bad tubes in the world will light up.

    So you may not know if the tubes are worth anything. This is especially true since the person who sold you that CB amp lied about the power it runs.

    The transformers and tubes might have some small value to other people, but the parts don't have nearly the value some people are suggesting or implying. No one in their right mind would pay very much for used sweep tubes in unknown condition from a CB amplifier.

    So unless you actually ran the amplifier and looked at the real RF output, you have no idea if it is good or not.

    My advice is you tote the amplifier right back to whoever sold it to you and see if he is man enough to give you your money back. Otherwise, I'm afraid all you can do is pass the bad Karma off on someone else and, like the guy who sold you the amp, lie to them and tell them you are selling them something of useful value.

    While a CBer might pay money for that amp intact, I'm afraid parting it out is not the big cash cow some might think. The parts would have some limited value to people who build things, but the only real value of that amp or the parts is to a CBer. Since you have no idea what condition the tubes and amp is in, it is impossible to assign a value.

    I'm sorry you got taken in by the fellow who sold you the amp, but things like that happen in life. Those are the lessons we learn best.

    I had a friend years ago that, when he would get a bad deal he would lie and pass it off to others. Some people have the morals to do that. I just can't bring myself to do that. It eats me up inside.

    73 Tom
  14. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Tom, in such a case I bring the gear to the local swap meet and when asked a question, I give a very direct answer:

    "Of all the rigs I've ever used, this is certainly one of them.":)

    You don't need to lie, or even exaggerate.

    I usually wink at the same time.;)
  15. KJ4ZIZ

    KJ4ZIZ Ham Member QRZ Page

    Well I don't lie about my items and it seem we are getting off the point of this discussion.
    Seeing that the amp is set up for 40 20 and 15 I don't see the problem...
    It has no cb band taps on the coil and I can see it working at about 350 to 450 watts with
    no problems... Also the drive needed is between 5 and 10 watts to get up to 350 to 525 watts out.
    I would think my Icom 706 could drive this on low power with no problem......

    Any suggestions are welcome...
    Richard KJ4ZIZ
  16. KF6ABU

    KF6ABU Ham Member QRZ Page

    now you know why people "rag" on you. Becuase you dont read, or listen to advice given.
    My suggestion would be to suggest you stop thinking you know what you are talking about.
  17. W8JI

    W8JI Ham Member QRZ Page

    You are not listening Richard. :) A local Ham in Griffin GA made the same mistake as you and bought one, and brought it to the local radio club. He , like you, kept insisting it would work. I looked at it for him here, so I have seen one first hand within the last five years.

    That amp had taps and a label for Ham bands, but it was obviously only to help the manufacturer avoid being busted. It was NEVER a Ham amp. The plate chokes and capacitors were too small to even work on 40 meters.

    It had long skinny-diameter silver color coils of heavy buss wire tied to the band switch.

    It had the wrong drive power requirements for Ham. The tubes, that are dirty enough when operated with stable voltages, were operated with a floating bias system. This self-bias is a way to increase swing.

    It had numerous other safety and design issues, including lack or equalizing resistors across filter caps and no bleeder resistors at all in most models. It can kill you five different ways, even when unplugged. He had his amp plugged in a day or two before he brought it here, and when I reached inside the cold amp I actually blistered the skin up on my fingers!! I got knocked on my rear.

    It was a hopeless POS.

    The final amplifier tubes has a floating bias system with no regulation. When we drove it with ten watts the bias went to 80 volts or more negative. Without drive it was about 18 volts.

    No matter what you want to believe, all you have is a cheap poorly-built CB amp that, if the tubes are good, can run about 300 watts PEP output or less. Please don't run crap like that on Ham bands.

    73 Tom

  18. KA7NIQ

    KA7NIQ Ham Member QRZ Page

    Richard, it is one thing to ask for advice, but for it to do any good, you must listen to it.
    Think about this, why will people pay 300.00 to 600.00 for a Used Ham Radio Amp, when they can have a Maverick 250 for 200.00 all day long ? The answer, although you may not want to hear it, is exactly what Tom (W8JI) told you.
    No Ham worth his license would ever run one of those amps on the Ham Bands.
  19. W0UZR

    W0UZR Ham Member QRZ Page

    That is a CB amp. Sure, go ahead and use it on 15/20 meters, if it will even work there which I don't think it will. If it does, then you can enjoy a lot of P$$D off hams that will tell you that your single is very wide and poor quality, flat topping and whatnot. You can enjoy a reputation amongst the ham community as the guy with the dirty CB amp. Get a REAL good antenna WAY up in the air and talk with 100 watts for a year or 2 like 99% of the rest of us did. Then if people still can't hear you then maybe get an amp. A GOOD amplifier designed for Amateur Radio..
  20. KJ4ZIZ

    KJ4ZIZ Ham Member QRZ Page

    OK now were getting to the heart of the matter. Yes I read and understood all the negative comments listed here and I even understand what Tom is saying. Thanks for the inside detail of the amp. I have been on 20 and 15 meters and get slammed on both sides of the freq when trying some dx work from hams who take up 10 mhz on both sides so it seems dirty amps are being used and if they are real ham amps as you say then the power level is way too high. My little 200 to 300 watts out isn't going to be any different then these hams.

    I try to understand how things work and Tom is the only one here who has tried to explain how this amp works...No I may be able to make the tap wires bigger and put in better filters to clean this thing up for use on hf.

    Yes I can fix many things if I understand how it works. That is why I was also looking for a copy of the manual.......
    If it gets too bad I can always sell it to South America.....seems they run way too much power down there as it is...LOL

    OK guys I appreciate the advice and I will now be back on the lookout for a good Heathkit sb 200 and a realistic price...

    I have 8 antennas up high and get out very well on my 100 watt rigs.....I also do QRP work on 30 meters. I may be newly licensed
    but I have been around ham radio from the seventies. At the contest club we run 1500 watts and our towers are 190 feet high.....
    I am not like the rest of you, But I hear what you are saying........

    Again thanks for the good info
    Last edited: Jun 16, 2011
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