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Thread: SB200 meter, Save that old dead carcass

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  1. #1

    Default SB200 meter, Save that old dead carcass

    I recently purchased an SB200. Its not a basket case, but needs TLC. One big deficiency is the meter. The original clearly blew up. The replacement was not badly done, but far from original. If you have blown one up, please SAVE the remains. I can change the movement. I might even rewind the coil. The important parts are the case and face. If you have one laying around, please reply. Thanks
    Kim, WA1PBU

  2. #2
    Join Date
    Nov 2005
    Location
    Deville, LA
    Posts
    20

    Default

    I have a couple of HM-102 wattmeters here and their meter cases and faces are similar to what the SB-200 uses but may not be an exact match. Obviously the scale is different and the basic meter movement f/s current may be different as well. It might be something to check into if you can't find an original SB-200 meter.
    Last edited by KD5R; 06-01-2010 at 07:18 PM.

  3. #3

    Default

    The cases, at least, on the meter movements of the SB-200 and the HM-102 and HM-2102 wattmeters are the same. At least the meters on my SB-200 and both my HM-2102 units are the same! I haven't checked the movements themselves to see if they are the same.

    Glen, K9STH

  4. #4

    Default

    Thanks for replying guys. I believe most of the Heathkit meters (of that vintage) used the same 200uA movement. The important parts (for restoring the amp) are the case and meter face. I don't think I would destroy a good HM102 for this. Movements can be found, and I can work under a microscope (if I limit the coffee intake). I have to think that others have blown up that meter too. The amp design has some shortcomings in that area. If I can find a couple, perhaps we can fix someone else's SB200 too.

    If you find someone has blown one up, please don't toss it. I have had little luck finding out what happened to the one from my amp. Someone did a pretty fair job of copying the scale to a replacement meter but it is not the correct size for the hole.
    73

    Kim Peck WA1PBU

    oh, got some power out of it last night (80M). Some RF in the shack. Need to work on the antenna and feed line now.

  5. #5

    Default

    Ive found many of the HM-102 meters to be 100ua and they work fine with a 15K series resistor. I do remember a few that were 200ua so make sure what you have.

    Carl
    KM1H

  6. #6
    Join Date
    Oct 2004
    Location
    Jacuzzi
    Posts
    12,786

    Default

    Remember you can protect the SB 200 meter by installing two 1N5408 diodes in parallel across the meter terminals in opposite direction of one another. (AK-KA configuration)



    Need artwork for a replacement meter?

    Last edited by KC8VWM; 06-30-2010 at 05:26 AM.
    73 de Charles - KC8VWM
    North American QRP CW Club #3159, SKCC# 5752

  7. #7
    Join Date
    Sep 2008
    Location
    Florida and Utah
    Posts
    20

    Wink Good Work

    Thanks Gents for your good work and thoughts on this subject. I rebuilt my SB-200 incrementally over the past several years. Still using the origninal finals -- 30 years later. I have to admit they were gassy. When I did the harbach softstart update, I made a wiring error which heated the plates cherry red -- realized the error and the upside was the tubes are now on steroids.

    73

    Mike Coburn W4TMC/7

  8. #8

    Default

    I haven't checked in for a while.

    Thanks to Charles - KC8VWM for the very nicely done artwork. I will put that on my present meter whatever else may happen. Turns out, my HM101 was also dead. The meter is from the "Ideal meter company" (not very). Looks like the solder flux was slightly corrosive. The diode protection is a good idea as well.
    73

    Kim Peck (WA1PBU)

  9. #9
    Join Date
    Oct 2003
    Location
    Middle Georgia USA
    Posts
    7,722

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