[Milsurplus] BC-9 Loop Test: Scratching My Head

[Michael Bittner]

In the broadest sense, it is a regenerative receiver.  Whether it's Armstrong, Hartley, or in this case Colpitts, regenerative feedback is happening and the signal is re-amplified through the regenerative process.



Thank you for pointing out the error in my redrawn schematic.  Change the connection to S2 to zero volts and the connection to the common ground (was +4 V) to minus 4 Volts and the diagram should be OK.



Thanks to the various contributors to this thread, I'm finally coming to an understanding of how this thing works.  It still looks like an interesting project for replication and further experimentation on the frequency offset situation.



I still haven't figured out how to use Google Photos in order to put into an email a URL that everyone on the list can access.  Help anyone?

 

Mike, W6MAB

 

  ----- Original Message ----- 
  From: Hubert Miller 
  To: Milsurplus at mailman.qth.net 
  Sent: Saturday, February 11, 2017 8:07 PM
  Subject: Re: [Milsurplus] BC-9 Loop Test: Scratching My Head


  People want to make it a regenerative receiver. It was never intended for AM reception. If you want to label it, it's called an 'autodyne detector'.  The bias pot sets the level of oscillation  and plate current. 



                                                                                                                                                                                                                                              

  If you had 2 of the SCR-77-A, the set with no dropping resistor, there is no receive-transmit offset. With 2 of these operating, just tune them 1 kHz apart

  and you're in business. Much more difficult with Dave's set !! If not impossible !

  I agree that some low-mu triode such as #30 might be a reasonable alternative. With socket adapter of some sort.

   

  Dentron had a novice ham radio transceiver, the "Station One", which never reached actual production, but also had no provision for CW RIT. Depended

  on the other station offset. The AN/ARC-2 is another one with no CW offset. 

   

  The redrawn BC-9 schematic needs to show B- going to the +4 battery.



   

  Again, i would just for fun, increase the value of the plate section of the feedback ratio capacitor. But i actually think there is NO complete resolution to the problem except to revert to

  the SCR-77-A  circuit. 

  -Hue 





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