Inexpensive SWL recievers

[Guy G. Giacopuzzi DDS]

Gary L. Sanders wrote:
>
> I had both the GR-64 and GR-54 when I was a teenager. The GR-64 is a
> simple regenerative receiver, but with a nice look. It does receive CW
> and SSB, but take some twiddling to bring in the signals right. The
> GR-54 is more sophisticated heterodyne with a tuned RF stage and
> selectable USB/LSB modes to ease SSB tuning.
>
> Now for why I responded to the group---
> If you have a GR-54, you can significantly increase the sensitivity of
> the receiver on each of the bands by increasing the Q of the circuits
> for each band on the RF PCB that is part of the band switch. As I
> recall, you increase the values of the resistor in each circuit until
> you reach a point where the receiver breaks into oscillation on that
> band, then back off on the value some, so it won't oscillate. It may
> help to experiment using a pot, then solder in a fixed value. You will
> now find that the receiver is more sensitive at a certain frequency in
> each band, so re-adjust the peaking coil for each band to maximize the
> sensitivity at those frequencies that you are most interested in. It
> makes a big improvement in performance.
> --
> Regards,
> Gary L. Sanders, Staff Analog Eng., gsanders at csidaq.com
> Celerity Systems, Inc., www.csidaq.com, A Microdyne Company
> Cupertino, CA USA (408) 873-1001 fx (408) 873-1397
> Ultra Fast Acquisition & Data Generation Systems
>
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> --- --- --- --- --- --- --- --- --- --- --- --- --- --Couple of questions...I wasn't aware the gr64 was regenerative; the bfo
control does behave like a regenerative control though.  Is it
regenerative?  The GR81 is, officially, regenerative though...
On the 54', what resistors do you change?  Do you add a variable
resistor somewhere as a regenerative control?  Please detail...
ggg

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