Panasonic Table AM/FM Radio Model RF 544

M

Mitchell McCreath

Guest
Hello all,
I have the the above mentioned radio. Though the audio sounds
great during the day, (Must have quite a good AF bandwith)
At night the problem of 9Khz whistle raises it ugly head.

Anybody got an idea to modify the radio (switchable) to
narrow its bandpass so that I can more enjoy listening at night?.

Regards,
Mitchell
 
"Mitchell McCreath" <mmoules@bigpond.net.au>

I have the the above mentioned radio. Though the audio sounds
great during the day, (Must have quite a good AF bandwith)
At night the problem of 9Khz whistle raises it ugly head.

Anybody got an idea to modify the radio (switchable) to
narrow its bandpass so that I can more enjoy listening at night?.
Click to expand...

** This site should give you a few ideas.

http://www.geocities.com/rbrucecarter/amaudio.htm




............ Phil
 
"Mitchell McCreath" <mmoules@bigpond.net.au> wrote in message
news:KDCZb.69300$Wa.11158@news-server.bigpond.net.au...
Hello all,
I have the the above mentioned radio. Though the audio sounds
great during the day, (Must have quite a good AF bandwith)
At night the problem of 9Khz whistle raises it ugly head.

Anybody got an idea to modify the radio (switchable) to
narrow its bandpass so that I can more enjoy listening at night?.
Click to expand...
Don't know about that model, but in general you could make a 9kHz notch
filter out of one or two op-amps. Then wire it into the receiver near the
volume control connections.

Peter
 
** This site should give you a few ideas.

http://www.geocities.com/rbrucecarter/amaudio.htm




........... Phil
Click to expand...
Thanks Phil. Doesn't seem to hard to make up. I'll delete the switch as far
as the notch
select is concerned. Now where did I put that veroboard :)

The only other pain in the but is radio 2 (1611KHz) which I can here softly
in the background
spaced apart at the IF frequency (455KHz).
Guess I can't really get rid of that because the TX site is only about 1 KM
away

Cheers,
Mitchell
 
On Sat, 21 Feb 2004 09:43:58 GMT, "Mitchell McCreath"
<mmoules@bigpond.net.au> wrote:

** This site should give you a few ideas.

http://www.geocities.com/rbrucecarter/amaudio.htm




........... Phil

Thanks Phil. Doesn't seem to hard to make up. I'll delete the switch as far
as the notch
select is concerned. Now where did I put that veroboard :)

The only other pain in the but is radio 2 (1611KHz) which I can here softly
in the background
spaced apart at the IF frequency (455KHz).
Guess I can't really get rid of that because the TX site is only about 1 KM
away

Cheers,
Mitchell


Hello Mitchel,
Click to expand...
For fun, in addition to the notch filter you could add a simple manual
RF gain control. Find the AGC line and with a suitable potentiometer
resistor arrangement (trimpots either side of the control pot) alter
the AGC voltage slightly.

You could fit a 3 position switch to have.
Normal AGC (original circuit without mod)
Manual RF gain no AGC
Manual RF gain with AGC

Easy to do with a signal generator to help you but
you could just muck about without one just for fun.
I am assuming you have a circuit diagram for your
radio, if you can't get one easily and cheaply then
forget my suggestion.

Regards,
John Crighton
Sydney
 
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