Heath HW-2036A PA amp no output

Discussion in '"Boat Anchor" & Classic Equipment' started by WB9TEN, Oct 30, 2018.

ad: L-HROutlet
ad: l-rl
ad: L-MFJ
ad: Subscribe
ad: MessiPaoloni-1
ad: Left-3
ad: l-assoc
ad: Left-2
  1. WB9TEN

    WB9TEN Ham Member QRZ Page

    Going through an HW-2036A tune up procedure in order according to the manual. The synthesizer tuned up, the exciter/transmitter tuned up, but the PA appears to be dead. I even swapped it with another PA that is of unknown integrity and that is also without output. This is what I know:
    • On transmit, it will "quiet" an HT next to it. Frequency changes track correctly.
    • I can hear the local repeater on a cantenna in my basement.
    • There is 13 volts DC on the PA board and the collectors of both transistors.
    • Using a Ramsey RF probe, there does appear to be drive to the PA board.
    • The relays check out with an ohm meter.
    • Power supply is a recapped HWA-3036-3.

    My questions are as follows:
    • What are the suggestions for troubleshooting?
    • If I pull the resistors off the base and the chokes from the collector to DC isolate those terminals, how does Q301 and Q302 check with an ohm meter?
    • What is the best way to unsolder Q301 and Q302 from the board without heat damage? I have a couple of HW-202 parts units laying around that could become donors.

    Thanks for any suggestions.

    73
    Dave
    WB9TEN
     
  2. W7UUU

    W7UUU QRZ Lifetime Member #133 Volunteer Moderator Life Member Platinum Subscriber QRZ Page

    Wow - a true labor of love trying to fix one of the most evil kits ever designed by the Hams at Heath! I applaud your effort. They're just so tight inside, and you move one thing to get to an area, and risk breaking other stuff in the process! I've owned several and hate working on them.

    I am friends with the chap who designed that very radio - Terry Perdue, K8TP who lives in my area. He told me that after that design project was finally done, and the kit was in production, that he attended a "post product release party" hosted by another friend, and former Ham at Heath, Bob Furnau W8NDG (who still lives in Benton Harbor) and they surprised him with a couple HW-2036A shop samples and a sledgehammer, and they all proceeded to take turns demolishing the radios and smashing them to bits!

    :)

    Dave
    W7UUU
     
  3. WB9TEN

    WB9TEN Ham Member QRZ Page

    Dave,
    I can believe the sledgehammer story but the HW-3026 inherited its design from the HW-202. I never did like the PA from a mechanical standpoint but it is cheap. This looked like a simple change the front panel and recap job and has become an albatross. I have an HW-202 paired with a GLB-400B and I thought that the 2036 could keep it company collecting dust. I even put a ComSpec PL deck in the 202 to use it with the local repeaters.
     
  4. WB5OYP

    WB5OYP Ham Member QRZ Page

    My 2036A I built in ( I think) 1978, still on the air, still works fine, never an issue. It served on a mountaintop for a couple of years as first packet repeater in No. CA in early 80's. My congrats to K8TP for a fb design.
     
    W7UUU likes this.
  5. W7UUU

    W7UUU QRZ Lifetime Member #133 Volunteer Moderator Life Member Platinum Subscriber QRZ Page

    Indeed. Terry is a really cool guy - lives near Seattle - if you're ever in the area, ping him - he'd very likely meet up. He has a super-tidy shack and tons of Heathkit memorabilia around including his original prototype of the HD-8999 "Super Keyer" - with an EPROM reader right in the top, to test software upgrades back in the day before committing to burning them to ROM. It was truly a pleasure in the last few months to spend an hour and a half with him.

    Amazing work designing that radio - nothing "easy" about it, given the era, the parts available, the size it had to be, and the fact it had to be a kit built by the average ham - no small engineering task there!!

    Dave
    W7UUU
     
  6. KA9JLM

    KA9JLM Ham Member QRZ Page

    I still have one, In the day that was a great radio.

    Does the signal meter show any power when you transmit ?

    Good Luck.
     
  7. AI3V

    AI3V Ham Member QRZ Page

    Test the final like any other bipolar transistor.

    Out of circuit you should measure a pair of diode junctions, b-e and b-c, and a open circuit both ways e-c.

    Do you have a rf probe for your voltmeter? They are easy and just about foolproof for chasing down a problem in a Tx chain.


    http://n5ese.com/rfprobe1.htm
    Rege
     
  8. WB9TEN

    WB9TEN Ham Member QRZ Page

    No signal on meter when I transmit and nothing at point C on the PA board. The meter works for Rx.

    The Ramsey RF probe plugged into my IM-28 (hows that for a mix of technology) shows a couple of volts at the output of the transformer between the exciter and the PA but nothing at the base of Q301. The Ramsey is much like the N5ESE link but I was too lazy to build one. But thanks Rege, the page has some really good information.

    When I changed out the PA boards I changed everything soldered to the board including the toroid transformers and the coax going back to the Rx board. That would leave the 9-pin harness and the RCA connector being the only common items. I've gone through the 9-pin harness with an ohm meter and measured voltage. The exciter tuned okay but I didn't put the RF probe on the RCA connector. That might be worth looking at but, as I stated previously, I can measure RF on the PA board.

    I think my next move will be to just line up all three PA boards that I've accumulated for this project, pull the DC chokes to open the DC path, and do an ohm meter comparison. I'm hopeful that will show which one of these critters is the fly in the ointment.

    I thought this was going to be an easy fix because the PA board I started with had a broken ground wire between the speaker and antenna jacks. The previous owner had soldered a RCA to BNC adapter that was must have rocked that little panel with the connectors until the wire broke. But, that is the life of boat anchor repair.

    Thanks for the feedback. I'll keep plugging away. This project was set aside because I had a minor back problem that required Lazy Boy therapy.

    73
    Dave
     
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    I hope the therapy worked.

    Do you know if the radio ever did work properly ?
     
  10. WB9TEN

    WB9TEN Ham Member QRZ Page

    Don,

    I don't know if the radio worked at one time but in all likelihood it did. There are enough witness marks such as grime around the knobs that makes me believe it was a working mobile at one time. I haven't discounted that possibility though. I recently went through an SB-630 that had wrong parts and three unsoldered joints. Everything else appears to work but I haven't tuned the Rx yet. That can't be too bad because I can hear a repeater two miles away on the dummy in the basement.
     

Share This Page

ad: chuckmartin