[HBR] Sorry for multiple postings

[Ron Barlow via HBR]

Hi Brian,

 By using a variation on the "regenerodyne" design, one CAN use a selective bandpass filter, in front of the regenerative (2nd) detector.

 This alternate scheme uses a tunable oscillator in the frequency conversion (1st detector) stage. The regenerative 2nd detector stage operates on a fixed frequency.

 AFAIK, the original fixed IF frequency "super gainer" scheme was innovated by Frank Jones, W6AJF, in the 30s. It used regeneration in both the 1st and 2nd detector stages. The 2nd detector was of the autodyne type.
 
 Later, the ARRL handbook contained info on a basically similar design (Simple-X Super, I believe it was called).
 In addition to using more modern, higher gain tubes, the ARRL design used a non regenerative 1st detector. The regeneration level of the 2nd detector was adjustable, but intended to be pre-set, and left alone, afterward. A separate BFO oscillator was used, instead of an autodyne detector.

 IMO, this configuration would allow one to avoid a problem with the BFO frequency tending to be pulled in frequency (or being locked at the frequency) of the high Q bandpass filter, that would very probably occur, with the autodyne configuration.
 Thus, the Simple-X Super type design would permit the user to achieve true "single signal" capability, by offsetting the BFO frequency from the bandpass filter frequency.

 My experiences with a straight regen receiver, would suggest that the variable frequency of the 2nd detector, in the regenerodyne, would require some readjustment of the regeneration control, when QSYing, and/or when dealing with varying signal strengths.
 Thus, I suspect that the Simple-X version would be less of a handful to operate, than the regenerodyne.
 Some of us may enjoy or at least be willing to tolerate a receiver that requires the manipulation of multiple controls, while tuning around the band, but others may be less receptive to this challenge.

 I have recently begun construction of a 3 tube superhet, but construction has been put on the shelf, for now, for various reasons.
 I find these bare bones receivers to be very interesting, and I wish you GL with whatever design you decide to construct.
 I hope to read about your results, in the future. 

                     GL & 73 de Ron  n4gjv
  
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On Fri, 5/23/14, Brian Burns <brianburns1066 at gmail.com> wrote:

 Subject: [HBR] Sorry for multiple postings
 To: "'HBR Receiver List'" <hbr at mailman.qth.net>
 Date: Friday, May 23, 2014, 9:30 AM
 
 Hello Bill,
 
 I'm sorry for the multiple postings---I have too many email
 addresses. Kees
 has straightened it out for me, so it shouldn't happen
 again.
 
 ~ I've not had much experience with these, except for cheap
 kits years ago.
 I saw your post several times now, but no responses so far,
 I wondered if
 you were familiar with the Regenx group, there, they
 specialize in your and
 related circuitry.
 
 Yes, I've been on the regenrx list for a couple of years
 now. There are some
 good threads there, but the hams seem to be mostly
 interested in
 experimenting and building, so I haven't had any luck
 getting information on
 how the various designs actually perform as station
 receivers.
    
 ~ As for me, I'm still looking for a couple of iFs : )
 
 Ain't that the truth! Back in the day (I'm 74) you could
 order up most
 anything, though it took a long time for it to arrive.
 
 The "regenerodyne" design has one so called I.F. transformer
 that you wind
 yourself. My main reservation about the design is
 selectivity in the
 presence of strong adjacent signals. It is after all a regen
 with a crystal
 controlled converter--no place to stick a crystal filter.
 
 Cheers,
 
 Brian