I purchased today a vintage Radio Shack Concertmate portable radio on the cheap which looks really good cosmetically outside of about a half inch of dust but has a very disheartening problem. Outside of a noisy volume control the FM band sounds great. The radio has 2 speakers, a balance control and a tone control. Very nice stereo separation for a portable. AM band was sounding equally as good as I tuned down from 1600 KHZ and picked up about 20 daytime stations. Once I got to 700 KHZ and tuned down to 530 KHZ there was nothing but static & a couple of random noisy spots. Very strange indeed as there is a power house radio station with its transmitter about 2 miles from where I live on 620 KHZ and another strong local station on 540 KHZ. First thought it might be a dirty tuning capacitor but I wouldn’t know for sure as I never encountered this before and I do own dozens of radios. Any ideas?
Radio Shack AM/FM with Limited AM Band Coverage
- Thread starter SatHunter
- Start date
a29zuk
Member
One possibility is the blow torch station on 620 khz is desensitizing that particular receiver at the lower end of the band.
You could try it at a more remote location to see if the problem persists.
Now that the 540 Windsor, Ontario station is off the air, Regina on 540 is easier to hear in my area! I don't believe I received the one on 620, though.
Jim
You could try it at a more remote location to see if the problem persists.
Now that the 540 Windsor, Ontario station is off the air, Regina on 540 is easier to hear in my area! I don't believe I received the one on 620, though.
Jim
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- Dec 19, 2002
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Before I read down to where you also conjectured it, I also suspected the tuning capacitor. It is acting exactly how I would expect if that were shorting once tuned past a certain spot.
It’s like it hits a dead spot - static, noisy & loss of reception. I came across something like this with old GE radio a couple of years ago. The string that moved the tuning indicator was binding & the tuning capacitor didn’t reach its full range causing a dead spot at the top end of the AM band. Also I noticed that KOA Denver at 850 KHZ is coming in at 790 KHZ on the dial so it’s not aligning properly. I hope to get this beast fixed up as it appears to perform exceptionally well on AM DX after testing it out for about an hour last night.
Today I took the back off the radio. Very dusty but the components such as the electrolytics look perfect. I used De-Oxit on all of the controls and got rid of the annoying static from the volume control. But now the tuning knob turns but the indicator doesn’t move and I can’t tune up & down the dial. If I put pressure on the string I can move the tuning indicator with my finger & I can go up and down the dial but only to about 1500 KHZ on the high end. I probably shouldn’t have sprayed the De-Oxit on the tuning knob shaft. Any idea what could have gone awry? Things have gone from bad to worse
Here is a photo with the back off the radio. The green circle shows the string attached to the tuning mechanism. The yellow circle shows the inner workings on the tuning knob I sprayed with De-Oxit. I’m not sure how to remove the cover to get to the tuning mechanism and string. I’m kind of afraid to take it apart as I haven’t worked on this type of radio before
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