Ken:
Yes! I just completed development and test of a really simple mod. I had
developed the mod that uses the mic. gain control but have since removed
that mod. This new mod is really simple and I did no drilling.
1) Remove the ground stud from the rear panel. In its place mount a
sub-miniature toggle switch. (These are the really tiny switches, not to
be confused with the merely "miniature" ones. The hole in the rear panel
will have to be enlarged very slightly, but the two solder lugs on the
grounding bus inside the radio will fit on the switch bushing just fine.
2) Run a wire from the "R" (regulated receive voltage) pin of connector
9 on the IF/Audio board to one of the switch lugs.
3) From the other switch lug, connect a wire with a resistor in series
with it to the emitter of Q5 on the IF/AF board. Its a little tricky
finding this point, but if you study the board and the schematic you
will locate it. (Hint: Find U2-5 and trace the circuit run to R15 and
then to Q5-E).
4) Resistor value selection is critical: 3.3 k-ohm gives lots of
attenuation. 3.9 k drops the IF gain only a little. I settled on 3.6 k
as the best compromise. Caution: Use a good quality resistor. I tried
some 3.6 k resistors that permanently shifted value up to 4 k after
soldering! I finally put in a 15k in parallel with a 4.7k resistor.
I out shrink sleeving over the resistor leads and just tied the wiring
down to the exisitng harness with a couple of small cable ties.
Now you have a handy attenuator switch. The resistor forms a voltage
divider with R80 to put about 4.65 to 4.75 volts of bias on the IF amps.
The AGC will still work, though the mod seems to increase AGC time
constant a bit.
73,
Bob
p.s. The Scout is a "keeper", but I'm really tempted by the Argo V.
Ken N9VV wrote:
Hi, I am trying to listen to my buddies on 80M at night and the
QRN is really tough. I can't find a way to crank down the RF Gain
on my Scout.
If I remember correctly, some guys worked out a way to modify the
rig to use the MIC gain as RF Gain. I don't want to mod the rig to
that extent. I was hoping to find a resistor that I can
temporarily change to keep this fine rig from blasting me out of
my chair?
suggestions?
mny tnx,
de ken n9vv
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