Loading ...
Sorry, an error occurred while loading the content.

Finished working on the "Mohican"

Expand Messages
  • Phil
    Yesterday I posted about recapping the Mohican and how much better it sounded, audio wise. Well, today I Went through and completely aligned it, using the
    Message 1 of 3 , Mar 19, 2014
    • 0 Attachment
      Yesterday I posted about recapping the "Mohican" and how much better it
      sounded, audio wise.

      Well, today I Went through and completely aligned it, using the Marconi
      2018A signal generator, something acquired at no cost in exchange for
      repairing and aligning a "Globe 'Ceiver" (an 'All American 5' clone of
      a Hallicrafters S-120). The 2018A is a VERY nice, all digital generator
      that in my mind rivals the best of the HP products. I used 2018's while
      working at General Dynamics and TRW-EPI. George, the ham who owned it
      couldn't get anything out of it and gave it to me in exchange for "labor".

      Well, it'd been a LONG time, over 20 years, since I last used one (a
      manual didn't come with it), but 30 minutes of "fiddling" refreshed the
      old memory banks and there was NOTHING wrong with it. The user
      interface just isn't at all intuitive ;-)

      The Mohican was another acquisition from the same man I got the
      generator from, at a very reasonable cash price. He said he'd aligned
      it using his mil-surplus generator. He's a ham and retired TV
      technician. Well, dial tracking was way off, and it turned out that the
      three upper bands were all aligned on the wrong side of the LO! The
      Heathkit manual is very clear on how to test for that, making sure that
      the image frequency is ABOVE the tuned frequency. Example: The image of
      8.5MHz, top end of "Band C" is 9.41MHz, after setting the dial for 8.5,
      you put the generator on 9.41 and make sure you can hear the generator
      at a weaker level. . . Sheesh, even a 10 year old can follow a Heathkit
      manual (I did when I was in my "pre-teens").

      Now it works well and is much more sensitive. There are some small dial
      errors in the middle of each band, but that is typical of consumer grade
      analog receivers and I DON'T feel like going through and "knife-edging"
      the tuning capacitor to improve tracking. This one is closer than many
      I've worked on anyway.

      One final and minor problem. The owner also replaced the BFO pot that
      apparently "fell apart". I need to eventually try to find a replacement
      for it as the one he put in is "off value", he trimmed it with external
      resistors, but BFO tuning is very non-linear.

      Later this summer I may refinish the cabinet and it'll be a very nice
      receiver. This was primarily a "Nostalgia Project" for me as I built
      one overseas somewhere around 1965.

      --
      73 de Phil, KO6BB
      http://www.qsl.net/ko6bb/ (Web Page)

      RADIOS:
      Grundigs: S-350 (~2006) & G6 (~2011).
      Heathkit: GC-1A "Mohican". Analog Solid State (~1965).
      Icom: R-75 Receiver with 2 Cascaded 250Hz CW Filters.
      Icom: R-71A With 500Hz CW filter (~1986).
      Icom: IC-735 Transceiver With 500Hz Filter (~1990).
      Radio Shack: DX-380 digital portable (~1990).
      Zenith: Royal-7000 Transoceanic Analog Portable (~1969).

      ACCESSORIES: Homebrew LF-MF Pre-Amp, MFJ-993B HF Auto-Tuner.
      Homebrew 6 Hz Audio Filter.

      ANTENNAS: 88' Long Ladder-line fed dipole at 35 feet AGL.
      Active Mini-Whip at 36 Feet AGL for LF/MW.
      30 Foot "Low Noise Vertical" for LF/MW

      Merced, Central California, 37, 18, 37N 120, 30, 6W CM97rh
    • Ed Cartwright
      Thanks for sharing Phil. Interesting and educational. 73 Ed N6MMW
      Message 2 of 3 , Mar 19, 2014
      • 0 Attachment
        Thanks for sharing Phil.
        Interesting and educational.

        73 Ed N6MMW


        On Wed, Mar 19, 2014 at 3:55 PM, Phil <ko6bb1@...> wrote:
         

        Yesterday I posted about recapping the "Mohican" and how much better it
        sounded, audio wise.

        Well, today I Went through and completely aligned it, using the Marconi
        2018A signal generator, something acquired at no cost in exchange for
        repairing and aligning a "Globe 'Ceiver" (an 'All American 5' clone of
        a Hallicrafters S-120). The 2018A is a VERY nice, all digital generator
        that in my mind rivals the best of the HP products. I used 2018's while
        working at General Dynamics and TRW-EPI. George, the ham who owned it
        couldn't get anything out of it and gave it to me in exchange for "labor".

        Well, it'd been a LONG time, over 20 years, since I last used one (a
        manual didn't come with it), but 30 minutes of "fiddling" refreshed the
        old memory banks and there was NOTHING wrong with it. The user
        interface just isn't at all intuitive ;-)

        The Mohican was another acquisition from the same man I got the
        generator from, at a very reasonable cash price. He said he'd aligned
        it using his mil-surplus generator. He's a ham and retired TV
        technician. Well, dial tracking was way off, and it turned out that the
        three upper bands were all aligned on the wrong side of the LO! The
        Heathkit manual is very clear on how to test for that, making sure that
        the image frequency is ABOVE the tuned frequency. Example: The image of
        8.5MHz, top end of "Band C" is 9.41MHz, after setting the dial for 8.5,
        you put the generator on 9.41 and make sure you can hear the generator
        at a weaker level. . . Sheesh, even a 10 year old can follow a Heathkit
        manual (I did when I was in my "pre-teens").

        Now it works well and is much more sensitive. There are some small dial
        errors in the middle of each band, but that is typical of consumer grade
        analog receivers and I DON'T feel like going through and "knife-edging"
        the tuning capacitor to improve tracking. This one is closer than many
        I've worked on anyway.

        One final and minor problem. The owner also replaced the BFO pot that
        apparently "fell apart". I need to eventually try to find a replacement
        for it as the one he put in is "off value", he trimmed it with external
        resistors, but BFO tuning is very non-linear.

        Later this summer I may refinish the cabinet and it'll be a very nice
        receiver. This was primarily a "Nostalgia Project" for me as I built
        one overseas somewhere around 1965.

        --
        73 de Phil, KO6BB
        http://www.qsl.net/ko6bb/ (Web Page)

        RADIOS:
        Grundigs: S-350 (~2006) & G6 (~2011).
        Heathkit: GC-1A "Mohican". Analog Solid State (~1965).
        Icom: R-75 Receiver with 2 Cascaded 250Hz CW Filters.
        Icom: R-71A With 500Hz CW filter (~1986).
        Icom: IC-735 Transceiver With 500Hz Filter (~1990).
        Radio Shack: DX-380 digital portable (~1990).
        Zenith: Royal-7000 Transoceanic Analog Portable (~1969).

        ACCESSORIES: Homebrew LF-MF Pre-Amp, MFJ-993B HF Auto-Tuner.
        Homebrew 6 Hz Audio Filter.

        ANTENNAS: 88' Long Ladder-line fed dipole at 35 feet AGL.
        Active Mini-Whip at 36 Feet AGL for LF/MW.
        30 Foot "Low Noise Vertical" for LF/MW

        Merced, Central California, 37, 18, 37N 120, 30, 6W CM97rh


      • Phil
        You re welcome, 73 de Phil, KO6BB http://www.qsl.net/ko6bb/ (Web Page) RADIOS: Grundigs: S-350 (~2006) & G6 (~2011). Heathkit: GC-1A Mohican .
        Message 3 of 3 , Mar 20, 2014
        • 0 Attachment
          You're welcome,

          73 de Phil, KO6BB
          http://www.qsl.net/ko6bb/ (Web Page)

          RADIOS:
          Grundigs: S-350 (~2006) & G6 (~2011).
          Heathkit: GC-1A "Mohican". Analog Solid State (~1965).
          Icom: R-75 Receiver with 2 Cascaded 250Hz CW Filters.
          Icom: R-71A With 500Hz CW filter (~1986).
          Icom: IC-735 Transceiver With 500Hz Filter (~1990).
          Radio Shack: DX-380 digital portable (~1990).
          Zenith: Royal-7000 Transoceanic Analog Portable (~1969).

          On 3/20/2014 2:29 AM, Ed Cartwright wrote:
          > Thanks for sharing Phil.
          > Interesting and educational.
          >
          > 73 Ed N6MMW
          >
        Your message has been successfully submitted and would be delivered to recipients shortly.