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

help for fixing HR-1680/HX1681 twins

Expand Messages
  • IZ0DIO
    Gentlemen, I have a problem with my HR1680 receiver; suddenly it stopped working on 20 m band and, after a quick check , I noticed that wasn t any signal
    Message 1 of 3 , Sep 29, 2013

      Gentlemen,

      I have a problem with my HR1680 receiver; suddenly it stopped working on 20 m band and, after  a quick check , I noticed that wasn’t any signal coming from HFO circuit board to the first mixer located on the front end circuit board. I checked switching diodes and coils on these (very simple) boards, concluding that the problem is due to crystal Y404 (22.895 MHz) not working any more.

      I switched off the receiver, waiting to find a proper crystal, but today, after a resting night, switching on the it again it works perfectly on 20 m band too. I’m wondering about the reason of this erratic behavior; band switch and all contacts seem to be ok and in my experience I never saw a crystal completely stopping oscillating after a warming up period (even if  it could  drift).

      Has anyone of you a suggestion to help me to fix the problem?

      Just in case, has anyone of you a crystal (#404-209) for sale?

      With the occasion, I’d like to know your opinion also on a HX-1681 transmitter I recently bought at a bargain exhibition. It seems to work properly on 80 m, 40 m, 20 m band giving low output on 15 m and 10 m band.

      I didn’t start working on it yet, but I would be glad to know your opinion about how to fix the problem; considering that the RF power on lower bands is close to 100 W and that it decreases to less then 10 W on 10 m band, it seems to me that it’s not just a neutralization problem.

      Thank you for helping and 73.

      IZ0DIO - Giorgio

    • jimtalt
      Hi Giorgio, I too have both of these units and had some fun getting them working. I ve found many Heathkits have problems with HFO s not oscillating on 20M-10M
      Message 2 of 3 , Sep 29, 2013

         Hi Giorgio,

         

        I too have both of these units and had some fun getting them working.

         

        I've found many Heathkits have problems with HFO's not oscillating on 20M-10M bands. Particularly 15M.  I believe this is the result of reduced crystal 'activity' as a result of aging. They work at first turn on when everything is cold but switch bands and then back, and the HFOr won't 'kick back in' on the problem band.  In the case of my HX-1681, I solved this by 'goosing up' the oscillator bias to drive it slightly harder for that problem band. Given that this is xtal aging, replacing the xtal with another, possible lazy, crystal may not fix your problem. On my unit I could see that the xtal had already been replaced...! So, try running the HFO on that band harder. In the instance of my SB-101 I increase the oscillator feedback by moving leads in the feedback path closer to one another.

         

        Re: Low power on your HX. I suspect those cheapo plastic trim caps on the ouput pcb. Here's the text from an earlier post that I think will tell you about several problems including your current one:

        .

        Intermittant pegging of Ip current was a cold solder joint at the pcb on the (-) bias line that runs to pin 5 of V2. This is a heavy guage 6 inch run of stiff unsupported wire that is only supported at the the tube at one end and the pcb at the other end. Years of expansion and contraction caused the problem.  I'd guess I will not be the only person that has/will have this problem.

        No output on 15 meters. Other bands work.  15 meter HFO not oscillating.  Found 15m xtal had previously been replaced! I was not the first person to have a 15 meter problem. New xtal was a Crystek. Swept xtal and found it to be resonant at proper 1/3 freq. Hoped that the problem was just that it was just not as lively as the orignal xtal so juiced up osc operating conditions to the same as those found in the 40m HFO circuit (about 16ma Ic) by adding new resistor in parallel on foil side of pcb.  15 Meters took off! Worked fine.

        Still low output on 15 even though HFO osc is running stronger than other bands. Found the bandpass filter board cheapo 1-8 pf cap in the 15meter leg is touch sensitive intermittant. Replaced and all is fine.

        Replaced 6146B's with 6146s. Neutralization is difficult because this circuit doesn't have a pronounced null. Got it neutralized but the adjustment of the cap is small and neutralization is subtle.
        Hope this helps someone else.

         



        ---In heathkit@yahoogroups.com, <heathkit@yahoogroups.com> wrote:

        Gentlemen,

        I have a problem with my HR1680 receiver; suddenly it stopped working on 20 m band and, after  a quick check , I noticed that wasn’t any signal coming from HFO circuit board to the first mixer located on the front end circuit board. I checked switching diodes and coils on these (very simple) boards, concluding that the problem is due to crystal Y404 (22.895 MHz) not working any more.

        I switched off the receiver, waiting to find a proper crystal, but today, after a resting night, switching on the it again it works perfectly on 20 m band too. I’m wondering about the reason of this erratic behavior; band switch and all contacts seem to be ok and in my experience I never saw a crystal completely stopping oscillating after a warming up period (even if  it could  drift).

        Has anyone of you a suggestion to help me to fix the problem?

        Just in case, has anyone of you a crystal (#404-209) for sale?

        With the occasion, I’d like to know your opinion also on a HX-1681 transmitter I recently bought at a bargain exhibition. It seems to work properly on 80 m, 40 m, 20 m band giving low output on 15 m and 10 m band.

        I didn’t start working on it yet, but I would be glad to know your opinion about how to fix the problem; considering that the RF power on lower bands is close to 100 W and that it decreases to less then 10 W on 10 m band, it seems to me that it’s not just a neutralization problem.

        Thank you for helping and 73.

        IZ0DIO - Giorgio

      • IZ0DIO
        Thank you for your reply and your suggestion. I agree on the fact that aged xtal sometime need to be overexcited and I’ll found the way to try. Again thank
        Message 3 of 3 , Sep 29, 2013

          Thank you for your reply and your suggestion. I agree on the fact that aged xtal sometime need to be overexcited and I’ll found the way to try.

          Again thank you.

          Giorgio – IZ0DIO

           

          Da: heathkit@yahoogroups.com [mailto:heathkit@yahoogroups.com] Per conto di atalt@...
          Inviato: lunedì 30 settembre 2013 05:03
          A: heathkit@yahoogroups.com
          Oggetto: [Heathkit:Yahoo] RE: help for fixing HR-1680/HX1681 twins

           

           

           Hi Giorgio,

           

          I too have both of these units and had some fun getting them working.

           

          I've found many Heathkits have problems with HFO's not oscillating on 20M-10M bands. Particularly 15M.  I believe this is the result of reduced crystal 'activity' as a result of aging. They work at first turn on when everything is cold but switch bands and then back, and the HFOr won't 'kick back in' on the problem band.  In the case of my HX-1681, I solved this by 'goosing up' the oscillator bias to drive it slightly harder for that problem band. Given that this is xtal aging, replacing the xtal with another, possible lazy, crystal may not fix your problem. On my unit I could see that the xtal had already been replaced...! So, try running the HFO on that band harder. In the instance of my SB-101 I increase the oscillator feedback by moving leads in the feedback path closer to one another.

           

          Re: Low power on your HX. I suspect those cheapo plastic trim caps on the ouput pcb. Here's the text from an earlier post that I think will tell you about several problems including your current one:

          .

          Intermittant pegging of Ip current was a cold solder joint at the pcb on the (-) bias line that runs to pin 5 of V2. This is a heavy guage 6 inch run of stiff unsupported wire that is only supported at the the tube at one end and the pcb at the other end. Years of expansion and contraction caused the problem.  I'd guess I will not be the only person that has/will have this problem.

          No output on 15 meters. Other bands work.  15 meter HFO not oscillating.  Found 15m xtal had previously been replaced! I was not the first person to have a 15 meter problem. New xtal was a Crystek. Swept xtal and found it to be resonant at proper 1/3 freq. Hoped that the problem was just that it was just not as lively as the orignal xtal so juiced up osc operating conditions to the same as those found in the 40m HFO circuit (about 16ma Ic) by adding new resistor in parallel on foil side of pcb.  15 Meters took off! Worked fine.

          Still low output on 15 even though HFO osc is running stronger than other bands. Found the bandpass filter board cheapo 1-8 pf cap in the 15meter leg is touch sensitive intermittant. Replaced and all is fine.

          Replaced 6146B's with 6146s. Neutralization is difficult because this circuit doesn't have a pronounced null. Got it neutralized but the adjustment of the cap is small and neutralization is subtle.
          Hope this helps someone else.

           



          ---In heathkit@yahoogroups.com, <heathkit@yahoogroups.com> wrote:

          Gentlemen,

          I have a problem with my HR1680 receiver; suddenly it stopped working on 20 m band and, after  a quick check , I noticed that wasn’t any signal coming from HFO circuit board to the first mixer located on the front end circuit board. I checked switching diodes and coils on these (very simple) boards, concluding that the problem is due to crystal Y404 (22.895 MHz) not working any more.

          I switched off the receiver, waiting to find a proper crystal, but today, after a resting night, switching on the it again it works perfectly on 20 m band too. I’m wondering about the reason of this erratic behavior; band switch and all contacts seem to be ok and in my experience I never saw a crystal completely stopping oscillating after a warming up period (even if  it could  drift).

          Has anyone of you a suggestion to help me to fix the problem?

          Just in case, has anyone of you a crystal (#404-209) for sale?

          With the occasion, I’d like to know your opinion also on a HX-1681 transmitter I recently bought at a bargain exhibition. It seems to work properly on 80 m, 40 m, 20 m band giving low output on 15 m and 10 m band.

          I didn’t start working on it yet, but I would be glad to know your opinion about how to fix the problem; considering that the RF power on lower bands is close to 100 W and that it decreases to less then 10 W on 10 m band, it seems to me that it’s not just a neutralization problem.

          Thank you for helping and 73.

          IZ0DIO - Giorgio

        Your message has been successfully submitted and would be delivered to recipients shortly.