wrote:
Folks,

I have a VFO/display problem with my Panasonic RF-3100.

I've had and used the radio for about 18 years. What I want to know
is could this be a simple `cleaning' `contact spray' solution, or
something more serious.

Photo of unit at: www.nyx.net/~wboas/rf3100.jpg

Here's the situation and symptom:

Radio has digital display and the bandswitch knob has 31 positions
covering 530-1600 Khz broadcast AM, 88-108 mhz FM, and 29 positions
to cover 1-29 mhz shortwave.

Up until a couple of days ago, display and performance was fine on
ALL bands.

However, all of a sudden, I lost the portion of the broadcast 88-108 mhz
FM band. At a point below 95.7 mhz the display turned to 9989.3 and
would not tune lower. Above that frequency the FM band works fine,
as does the full range of all the other bands.

Would anyone have a clue about why this is happening?




Probably not something that would be cleaned up with contact
spray. If the symptoms occur at the same point on the spectrum,
and consistently, you might try operating the radio on batteries for
a moment. See if the point of failure is different than the point
of failure on mains power.

If there is a difference, then at first blush, it looks like your
HF oscillator is becoming unstable, or ceasing oscillation. Or your
RF-IF stages are no longer tracking.

At this age, you'd be eligible for an alignment touch up. Or more
the more involved replacement of components out of tolerance.

If you've been noticing your dial calibration is off, this is
also indicative of drifting components.

I"m getting to the stage where an alignment and recapping of my
own RF-3100 is going to be a necessary.

It's not difficult. And the receiver isn't that complicated.


Fun radio, and I"ve dragged mine around the country behind me for
years. Not in the same class as most of my rigs, and it is subject
to easier overload than many, but mine isn't going anywhere. It's
definitely worth the attention to bring it back to spec.


Increasing the coupling capacitors along the audio path, and from
the detector to the output will improve bottom end response on
headphones and external speakers.


p


The FM broadcast band is not that important as long as all shortwave
bands work, but is it something that might deteriorate further?

Any comment or help would be most welcome.

Bill