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SB-200 Looking for the T/R relay? Harbach sold out.

Discussion in 'Amateur Radio Amplifiers' started by KD0SGX, May 10, 2020.

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  1. KD0SGX

    KD0SGX Ham Member QRZ Page

    I have had some issues over the past few years with the relay not working properly it's old an tired want to just replace it. Searching around and cannot seem to find any new ones...If anyone has one or know where to source one that would be great.
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    This is where I bought one for my SB-200 but it looks like they're currently out of stock. You might contact them to see if they plan to get more of these:
  3. KD0SGX

    KD0SGX Ham Member QRZ Page

    I had already sent them an email today, but since it Sunday I was asking here in case someone else might no some secrets or if you can use another manufaturer part with slight modifications.
    K7TRF likes this.
  4. W1QJ

    W1QJ Ham Member QRZ Page

    Jeff was unable to get his usual Midtek (sp) relays at least a year ago. He found a different source and sent me a sample of the relay he wanted to replace the other one with for beta testing. Since the relay impedance is part of the bias circuit, the series resistor must be calculated to provide normal idle current. When he sold the Midtek relay he provided a resistor to replace the stock relay. I took the relay he sent and calculated the series resistance needed and installed it in one of my amps. The relay worked fine with the resitor I calculated and got the normal idle current. I thought the relay worked OK and gave him a green light and a resistor value to provide with the relay. For some reason that I don't really know he decided to not provide that relay. I am not sure but I think he said he wasn't happy with the quality of that relay and never sought out another replacement. The relay needed is standard 11ovdc relay DPDT with suitable 10 amp contacts. There are many possibilities out there. If you select a relay don't forget that the series resistor has to be calculated to provide the proper idle current. It can be plus or minus a few mills and it won't hurt anything, but it should be close.
  5. KD0SGX

    KD0SGX Ham Member QRZ Page

    Awsome update, I still am looking for any recomendations on replacements or links to place to get one. Thanks for the update, Jeff did reply to my email saying he does not have a replacement at this time.
  6. KD0SGX

    KD0SGX Ham Member QRZ Page

    Where to source new or replacement relay. Also can I just measure the resistance with the coil and resistor, and then when i get a replacement relay just make the resistance the same?
  7. WA7PRC

    WA7PRC Ham Member QRZ Page

    Jim @W7RY sells relay driver PCBs for many ham amplifiers, and has one for the SB200/201 ( It drives vacuum relays that are everywhere.

    The vacuum relays toggle much faster, curing "hot" switching and the sealed contacts will never oxidize due to "dry" switching. The board makes your SB-200 T/R control input compatible with ALL rigs.

    Yes, W7RY's board & relays costs more... ONE time.
  8. KD0SGX

    KD0SGX Ham Member QRZ Page

    Seems like a cool Idea, looks like he just sells the board and you have to make it, which I am fine with as long as it comes with a list or cart filler. Wonder if it comes with pictures or video of installation in AMP. (I sent an email to W7RY)I have to belive others have found a replacemnet relay to bring the old AMP back to life before now?
  9. W1QJ

    W1QJ Ham Member QRZ Page

    Be advised this W7RY plan requires grounding of the grids and complete requiring of the bias and metering circuits. Unless you really need QSK I’d suggest just replacing the standard relay. I believe I’ve got a good used stock relay.
    KD0SGX likes this.
  10. KD0SGX

    KD0SGX Ham Member QRZ Page

    I don't need it to last another 60 years as I wont be here:). A replacement relay will be fine.

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