Well done, it is moisture ingress that causes this common fault, you just got rid of the moisture by leaving the radio switched on
I have known a radio to be set on a radiator for a couple of days have the sam effect
cheers
MM0HDW
Quote:
Originally Posted by Bob_KA1GT
NOTE: After writing the following and checking back with the FRG-7700, it now appears to be working again. It's been on now for maybe 48 hours, so the trick of leaving it on for long enough seems to have "fixed" the problem.
I'm not sure now whether it was working when I took the measurements.
The voltage at TP3 varies smoothly with the VFO. It can be anything from <2v to >8v depending on the band selected and the VFO setting. The range on any one band is around 1v or so. I believe this is the voltage being supplies to each of the VCOs by the MB-8718. This suggests the VFO is fine and the MB-8718 is fine. I have yet to find a datasheet for the MB-8718 or found a reference to what the voltage range on TP03 should be
The 47.6 MHz oscillator itself appears to be working OK, I don't think the counter has a problem. The radio isn't tuning when the VFO changes. One of the band switch positions seems to put the displayed frequency around 6MHz and U have heard a SW broadcast station there which was not affected by tuning.
Now it's fixed itself I can't do anything else to find out what the problem was of course. I suppose I could leave it off for another year and see if the problem re-occurs. It's sort of sounding like it might be the wax in the VCO unit. I can't be 100% sure it was still faulty when I made the measurements at TP03 since I wasn't watching the display and didn't have the audio turned up.
Anyway thanks for all the help and advice. Next time it happens I'll know better where to start and I'll post here again with an update (and probably a request for help!).
73, Bob
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