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32671Re: [Heathkit:Yahoo] Heathkit HM-2102 Watt meter problems

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  • bobfburns2000
    Jan 15, 2014
      I have just repackaged an HM2102 and I installed preset pots for all power ranges to enable precise calibration.
       
      I also replaced all out of tolerance resistors and found that the adjustment null was much sharper on 50MHz than 146MHz.
       
      Now works well.
       
      You can see the unit in the following photo on my technical website. The HM2102 is in the lower centre in a die cast box and the yellow multi-turn miniature presets are on the switch wafer to the lower right. The left hand half of this dual Z-Match ATU covers 1.8 - 30MHz and the right hand half covers 50 - 146MHz and it is used with a stub loaded multiband dipole fed with narrow spaced open wire feeders. The HF SWR/Power detector is a repackaged HM102.
       
       
      73

      Bob

      Bob F Burns G3OOU
      C Eng, FIET, MSE
      G-QRP 6907
      Secretary of Crystal Palace Radio & Electronics Club: www.g3oou.co.uk
      Technical web site: www.qsl.net/g3oou
      @BobFBurns on Twitter: http://twitter.com/BobFBurns
       
      In a message dated 15/01/2014 03:03:50 GMT Standard Time, wb4fen@... writes:
       

      Bob,

      The problem you describe is common to the HM-102.  A fix was published in Ham Radio magazine a several years ago.  I believe that the fix involved installation of a potentiometer.  I will peruse my old HM-102 manual and see if I made any notes.  Meanwhile some other old-timers might remember this issue.

      John, WB4FEN

      From: heathkit@yahoogroups.com [mailto:heathkit@yahoogroups.com] On Behalf Of K5MYJ
      Sent: Tuesday, Jan uary 14, 2014 5:05 PM
      To: heathkit@yahoogroups.com
      Subject: Re: [Heathkit:Yahoo] Heathkit HM-2102 Watt meter problems

       

      You need to do the calibration on the dummyload.

      It looks like you have a resistor that has changed value.

      Bob Macklin
      K5MYJ
      Seattle, Wa.
      "Real Radios Glow In The Dark"

      ----- Original Message -----

      From: Bob

      Sent: Tuesday, January 14, 2014 1:35 PM

      Subject: Re: [Heathkit:Yahoo] Heathkit HM-2102 Watt meter problems

       

      Bob, actually I used a dummy load and then just to compare I switched to the antenna and got almost identical results

      Bob

      W1GTH

      ----- Original Message -----

      From: K5MYJ

      Sent: Tuesday, January 14, 2014 1:35 PM

      Subject: Re: [Heathkit:Yahoo] Heathkit HM-2102 Watt meter problems

       

      Are you testing using a dummy load or an antenna?

      Bob Macklin
      K5MYJ
      Seattle, Wa.
      "Real Radios Glow In The Dark"

      ----- Original Message -----

      From: Robert

      Sent: Tuesday, January 14, 2014 9:31 AM

      Subject: [Heathkit:Yahoo] Heathkit HM-2102 Watt meter problems

       

      Has anyone experienced this problem with the VHF HM-2102 Watt/SWR meter?
      I am using it with a Kenwood 241-A 2 meter tranciver. I have checked the set with a known good watt meter and the results were: low power is 6 watts. Medium power is 10 watts and high power is 50 watts which is close to the values in the Kenwood manual. There are two scales on the meter, a 0-25 watt scale and a 0-250 watt scale. With the HM-2102 connected If I set the meter to read corectly on the 25 watt scale with the 200K pot it will only show about 40 watts on the 250 watt scale. There is no problem with calibrating the SWR by finding a null with the 200K pot, only a problem with the power readings. If I set the meter to read correctly on the 250 scale it will read very high on the 25 watt scale. I have checked all resistors and replaced two that were out of tolerance.
      Any thoughts?
      Thanks
      Bob W1GTH

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