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

From:

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.

I've had similar problems with a Sony 6800W. Try some DeOxit spray on the
inside on the bandswitch knob. If you aren't that courageous, try repeatedly
switching bands for several minutes and see if that helps.


Michael Bryant, WA4009SWL
Louisville, KY
R75, S800, RX320, SW77, ICF2010K,
DX398, 7600G, 6800W, RF2200, 7600A
GE SRll, Pro-2006, Pro-2010, Pro-76
(remove "nojunk" to reply)

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

= = = ocom (Michael Bryant) wrote in message
= = = ...
From:

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.

I've had similar problems with a Sony 6800W. Try some DeOxit spray on the
inside on the bandswitch knob. If you aren't that courageous, try repeatedly
switching bands for several minutes and see if that helps.


Michael Bryant, WA4009SWL
Louisville, KY
R75, S800, RX320, SW77, ICF2010K,
DX398, 7600G, 6800W, RF2200, 7600A
GE SRll, Pro-2006, Pro-2010, Pro-76
(remove "nojunk" to reply)


MWB,

I would stay away from such words, that sound like l"DeOxIt"
as they may encourage a 'rejoiner' from someone you know.

Just for the Fun of It ~ RHF

..

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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In article Pine.SUN.3.96.1040527134835.22092A-100000@nyx10,
wrote:
Folks,

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

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.

Does it pick up signals and just not display the frequency? Or
does it quit working below that point?

In the first case, it's probably the circuitry that converts the
local oscillator to the digital signal that feeds the display
electronics. (Buzzword: Prescaler). Or the oscillator is weak
and not providing enough signal. (For the second case, the tuning
capacitor the other poster mentioned is a strong possibility).

I had a several similar problems in my similar vintage Kenwood
R-1000. The first case was a poorly aligned filter on the
frequency synthesizer board, the second was a bad connector in
the power supply, and the bandswitch needs a shot of tuner-lube
every five years or so.

Mark Zenier Washington State resident

From: (Mark Zenier)

I had a several similar problems in my similar vintage Kenwood
R-1000. The first case was a poorly aligned filter on the
frequency synthesizer board, the second was a bad connector in
the power supply, and the bandswitch needs a shot of tuner-lube
every five years or so.

The shot of tuner lube has worked on my sony 6800W when it was acting very
similarly.


Michael Bryant, WA4009SWL
Louisville, KY
R75, S800, RX320, SW77, ICF2010K,
DX398, 7600G, 6800W, RF2200, 7600A
GE SRll, Pro-2006, Pro-2010, Pro-76
(remove "nojunk" to reply)

Michael Bryant wrote:

From: (Mark Zenier)

I had a several similar problems in my similar vintage Kenwood
R-1000. The first case was a poorly aligned filter on the
frequency synthesizer board, the second was a bad connector in
the power supply, and the bandswitch needs a shot of tuner-lube
every five years or so.

The shot of tuner lube has worked on my sony 6800W when it was acting very
similarly.

I don't recommend that for his problem.


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http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
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In article , starman wrote:
Michael Bryant wrote:

From: (Mark Zenier)

I had a several similar problems in my similar vintage Kenwood
R-1000. The first case was a poorly aligned filter on the
frequency synthesizer board, the second was a bad connector in
the power supply, and the bandswitch needs a shot of tuner-lube
every five years or so.

The shot of tuner lube has worked on my sony 6800W when it was acting very
similarly.

I don't recommend that for his problem.

Yea, I got an email from them saying that it quit halfway down the dial,
so it's in the oscillator tuning.

If the Band switch were the problem, it would affect the entire FM band.
Either causing the FM band to not work at all, or intermittent jumping
between bands.

The band switch, at least in the case of my Kenwood, an etched circuit
board based rotary switch. IMHO, their construction is marginal.
It's very expensive to make a switch with better quality contacts with
this small spacing. Tuner lube, in moderation, will fix these switch
problems, temporarily.

Mark Zenier Washington State resident