
May 28th 04, 08:02 AM
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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?
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
9989.3 is the off-set frequency for the display, which is actually a
frequency counter. This is what it shows if there is no FM oscillator
signal to measure. If you add the receiver's FM I.F. frequency of 10.7
to 9989.3 you get 10000.0 It's not important to understand what that
means but it does indicate that the FM oscillator is quitting. This
could be a problem with the FM oscillator section of the variable tuning
capacitor. It may have become contaminated with something which is
making it stop functioning properly when it gets to the 95.7 position.
The cap' has several sections. Some of them are only for the FM band.
That's why the radio works all right on the other bands.
IMPORTANT: DO NOT spray the tuning capacitor with anything to clean it!
The variable capacitor in the RF-3100 is like the kind found in small
transistor radios which use thin plastic separators between the metal
plates. Those separators will hold the spray fluid. Then you would have
to disassemble it to dry everything out. That would be a nightmare.
OTOH- You may have to disassemble the variable cap' to find out what
might be wrong with it. It's not a job for an amateur technician. There
are a lot of small parts. I suggest you continue to use the radio for a
while to see if the problem goes away, assuming it's the tuning cap'
that's at fault. You can try turning the tuning knob rapidly back and
forth near the problem position to possibly dislodge a foreign particle.
Good luck.
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