[HomeBrew] Panadaptors

Tue, 29 Jul 2003 13:45:56 -0700

The crystal would define the bandwidth that is being sampled, in the
same way that a crystal filter in a normal superhet. So the display at
some time would represent the energy present in a frequency slot equal
to the width of the 1-crystal filter.  This slot is swept over the
500kHz (or whatever) being monitored as the HFO frequency is swept.

It would be a fun project to redo this for an LCD display rather than a
CRT.

Hope this helps

73 de ian, K3IMW/6

> -----Original Message-----
> From: [email protected]
[mailto:[email protected]] On Behalf Of WB6BLV
> Sent: Tuesday, July 29, 2003 12:30 PM
> To: [email protected]
> Subject: [HomeBrew] Panadaptors
> 
> ** Please do NOT cross-post messages to multiple mailing lists on the
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> 
> Many years ago I constructed a very simple Panadaptor,
> so I could see about 500 KHz of each band I used.  It has
> been so long since I used it that I have forgotten the purpose
> of the crystal in the last receiver stage of the adaptor.  Anyone
> who might be able to help, I will gladly send you the schematic.
> 
> As I recall, the unit samples the output of the first mixer in the\
> Rx, and heterodynes it with a local HFO that is swept in sync
> with the sweep of the display CRT.  Then come a stage of
> intermediate frequency amplification, then this crystal stage, then
> a diode detector to drive the vertical plates of the CRT.  I wonder
> if the crystal is used as a second mixer to rescale the sample to
> original frequency, since the crystal matches the offset of the HFO
> from the sample exactly.
> 
> Any assistance appreciated
> 
> John
> 
> 
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