[Boatanchors] Mixer Troubleshooting Question For my Homebrew Superhet Novice Receiver

[Bill Meara]

 Scott: I checked mine and I was listening comfortably to 40 meter SSB contacts with on an UN-AMPLIFIED speaker.    I checked on the filter.  Turns out I have an old Millen Hi-Q IF transformer in there.  Inside a Millen 61455 IF Transformer


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Inside a Millen 61455 IF Transformer

Radio electronics blog. Homebrew ham radio. SolderSmoke podcast. QRP
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I will try to upload the video to YouTube and pass you the link now.  
Bill 

    On Sunday, February 28, 2021, 12:23:45 PM EST, Bill Meara via Boatanchors <boatanchors at mailman.qth.net> wrote:  
 
  Scott:  I will pull mine off the shelf and fire it up.   I'll shoot a video to give you a sense of how mine sounds.  
I suspect that yours may just need more peaking and tweaking.   I usuually find that I have to gradually coax signals out of a new receiver.  
I never had problems with the uncoupled BFO.  But on SSB I often have to back off on the RF gain to keep the signals at the right level for proper demodulation. 
I'll try to make some video now.  73  Bill     On Sunday, February 28, 2021, 12:19:07 PM EST, <whitebear1122 at comcast.net> wrote:  
 
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Hi Bill and List, Thank you for your advice.  Yesterday I made good progress and was able to at least hear the sig generator signal on the headphones in spite of the IF frequency problem.  This morning I moved the HF oscillator down so the IF frequency was around 453 KC and tuned L5 properly (unlike yesterday) which is ahead of the 453 KC crystal(s) filter.  It looked to be working so I hooked up an antenna and I heard 40 m FT8 and some cw signals albeit I am straining to hear it in the headphones.   Also I’m not getting enough BFO. Either it stopped working or it’s not coupling enough.   McCoy did not capacitor couple the BFO to the mixer but instead reported that interelectrode tube capacitance coupled adequate BFO to the mixer.  

  

My question for you is this:  I watched your youtube videos on the MMMRx plus I came across this statement on the glowbugs:  I thought about putting another stage of AF amplification in there, but the Sixer chassis is getting a bit crowded and I decided not to push my luck - too much AF gain on too small a chassis might cause the kind of feedback trouble that I've completely avoided on this project. The RX works fine with headphones, and for speaker operations I just plug in one of those computer speakers with an internal AF amp. Works great!

  

When I listen, I’m really straining to hear signals.  I’m even using my Trimm high impedance crystal headphones and it’s difficult to hear.  You said yours was ‘fine with headphones’.  Just how fine was it?  Did you hear background band noise?  Was the volume comfortable?  Did you get too much volume and have to use the RF control?  I can hardly hear it.  This afternoon I’ll start looking at the audio amplifier section and see if I have something wrong in there.

  

Thanks. 73, Scott WA9WFA

  
  
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