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

[Michael Bittner]

My first 1-tube radio, at Cub Scout age, was the Electrokit #1 that had a continuously running Colpitts oscillating detector with no regeneration control.  The ease with which it could be tuned to zero-beat on strong BCB stations indicates that said stations must have been pulling the oscillator.  Tuning weak BCB to zero-beat was extremely difficult, but it worked. I have posted the Electrokit schematic along with my revised schematic of the BC-9-A at: https://photos.google.com/album/AF1QipMcbDYu2T5UqFGM1i9hArx3PweTpaeVSUhSPlPK

In order to receive CW on the BC-9, its Colpitts oscillating detector must be offset from the received frequency by an audio amount, but I don't see any control for doing this.

All of the triode grids have a slight negative bias due to the battery connections.  Increasing the R4 rheostat increases the negative bias on the RF triode.  Is this a regeneration control?

I still don't get how the controls work for transmit and receive.

Someone suggested a replica using 01A or type 30 triodes.  I was thinking of using 955 or 958A acorn triodes for a miniature version with cool factor.

Thanks, Dave for posting my schematic.  I think I've figure out how to use Google Photos now.

Mike, W6MAB
 




----- Original Message ----- 
  From: Hubert Miller 
  To: milsurplus at mailman.qth.net 
  Sent: Saturday, February 11, 2017 2:51 PM
  Subject: Re: [Milsurplus] BC-9 Loop Test: Scratching My Head.


  A regen receiver can pull to a strong signal up to maybe 100s of Hz, maybe a kHz, depending on circuit and frequency. 

  The SCR-77 manual states range up to 5 miles.

  BTW, in correct terms, the BC-9 receiver is not a regenerative receiver; it's an oscillating detector. 

  The thing seems like a pretty "experimental" set at the that time. I wonder how successful it was. 
  -Hue

   

  From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of k2cby
  Sent: Saturday, February 11, 2017 2:40 PM
  To: milsurplus at mailman.qth.net
  Subject: [Milsurplus] BC-9 Loop Test: Scratching My Head.

   

  I seem to recall somewhere that a strong received signal could pull the frequency of a regenerative receiver to a certain extent. Has anybody tested the BC-9 with a signal generator run "wide open"? After all, the BC-9 was never intended to communicate over long ranges.

  Miles B. Anderson, K2CBY
  16 Round Pond Ln.
  Sag Harbor, NY 11963

  k2cby at optonline.net

   

   



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