Author Topic: Help to repair an Icom R72 receiver  (Read 837 times)

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Offline mehdi

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Help to repair an Icom R72 receiver
« on: December 01, 2015, 11:28:55 pm »
Hi
It is my first serious attempt at repairing a receiver and I need help.
I've got an Icom R72 communications receiver.
It's deaf on frequencies between 11.000 MHZ and 14.999 MHZ, but working on other frequencies (I've tested local AM stations and 7, 18 and 21 MHZ )
The service manual states that there are 6 bandpass filters and one of them is for 11-15MHZ



When I connect the output of my signal generator to its antenna input (for example with a 14MHZ signal), I can hear a tone which changes when I change the modulation on signal generator.
I'm not sure whether the oscillator is not working or the bandpass filter is faulty.
Can someone help me on my next step to find the faulty part?

Here's the service manual: www.radiomanual.info/schemi/IC-R72_serv.pdf

Tools that I have: Oscilloscope, DMM, signal generator (with AM/FM modulation), frequency meter.

Thanks
 

Online PA0PBZ

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Re: Help to repair an Icom R72 receiver
« Reply #1 on: December 01, 2015, 11:44:00 pm »
Check the diodes that switch the BPF, I think it is D31 and D32 for 11-15MHz.
Also check that the output of IC3 correctly powers the diodes for each band.
Keyboard error: Press F1 to continue.
 


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