[ARC5] GRC-9 BFO

[Peter Eijlander (PA0PJE)]

The designers must have had stockpiles of 1R5's to use them as BFO and 
as crystal calibrator. I think I would have used that 1R5 BFO as product 
detector rather than feeding that diode, and driving the 3rd grid with 
IF instead of tying it to ground, and then take audio from the anode... 
Well the BFO does a good job if sigs are not too strong and lock HFO and 
BFO firmly to zero beat.

Peter,
PA0PJE

Sorry Wayne, should have sent it to the list.

Op 21-04-2020 om 19:01 schreef Robert Eleazer:
> The GRC-9 receiver has a 456 KHZ IF and a BFO that runs at half the IF frequency, 228 KHZ.  I've never seen this done before.
> 
> Based on my own experience with adding a BFO to a SW receiver I can only assume this design feature is to prevent the harmonics from the BFO from overloading the receiver.  The receiver covers 2-12 MHZ so nothing below the BFO 10th harmonic could get into the set, and I assume that by that point the signal level is low enough to not be a problem/
> 
> Wayne
> WB5WSV
> 
>   
> 
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