[R-390] AGC problems

[Norman Ryan]

Hello, Ivan,

This sounds like a problem in the AGC line-- possibly a leaky cap, an
off value resistor or bad mechanical filter.  Do you experience this at
all Bandwidth settings?  The audio distortion may be related to the AGC
problem.  Before considering modifications, eliminate the problem
first.  You may find the audio to be OK.

1. Remove the IF deck.
2. Attach the knob to the Bandwidth switch shaft.
3. Do resistance measurements according to the manual.  When you find a
resistance value way off normal, turn Bandwidth knob to see if the value
changes.

If it's a bad mechanical filter, resistance measurements at the
connector will differ depending on whichever position the bandwidth
switch is set.  Ordinarily, the resistances should not vary
significantly no matter where the Bandwidth is set.  Chances are you can
isolate the fault simply by measuring resistances and comparing them to
the chart in the manual.

Good luck-- please let us know how it goes.

73 de Norman KG4SWM


�yvind wrote:
> 
> Can somebody tell me what the problem could be on my R-390-A, that i just
> bought.Strong stations completely overrides my AGC, i have to back off on
> the RF-Gain to get a reasonably readable signal.I figure there must be a fault
> somewhere.