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I have an old ICOM R-71a receiver that is giving me grief. The problem started off with audio and rf cutting out completely after being on for a few hours. The frequency display would work but nothing else. After shutting off the unit for a while and turning the unit back on then everything would operate as normal then recur later.

Now another problem occurs. Now everything below 8 MHz is silent but everything above 8 MHz still works but doesn't seem as sensitive as before. This is beginning to annoy me. Any ideas or suggestions on what's going on? I suspect a power supply problem. I have a nice 40 meter vertical antenna that is going to waste.....

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  • $\begingroup$ My first feeling was that 8 MHz sounds like a reasonable IF for a superhet. And sure enough, RigPix has a user's manual available for download that states that the first IF is at 70.4515 MHz and the second and fourth IFs are at 9.0115 MHz. That's close enough to what you claim that it sounds significant; I would probably check the filters around the second IF to see if there's something iffy going on there. At the very least, I would remove and try to clean any installed add-on filters, if the R-71A allows for such; otherwise, check the PCBs around that area. An oscilloscope may be useful. $\endgroup$ – a CVn Jul 25 '16 at 19:26
  • $\begingroup$ @MichaelKjörling: I tried an old method out of frustration. I gave the unit a somewhat vigorous thrashing in the vicinity of upper rear left quadrant.. Oddly enough that seemed to work for the time being. $\endgroup$ – Old_Fossil Nov 27 '16 at 8:28
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I have just joined so have to answer instead of commenting (not enough reputation yet). I have one of these receivers and know a little about them (I have to say it performs excellently and is very nice to use). They are now fairly old so are a bit prone to dry solder joints and dry caps. There are quite a few plugs/ connectors that can occasionally give trouble too.

The power supply uses a linear regulator with about 8v across it at >1A and runs quite hot, which commonly gives trouble and heats up the area around it, resulting in accelerated aging of some joints, caps, etc. A small well shielded and properly bypassed DC-DC buck converter cures this - they are very common and cheap now, well worth doing.

It's worth mentioning that there is a small 3v lithium backup battery on the RAM unit, if this goes flat the radio goes stone deaf (brain dead). I think it's supposed to last many years but there is a procedure for replacing it before this happens (maintaining the back up voltage at all times!) or replacement non-volatile "RAM" units are available (it is possible to reprogram it but it's a bit of a muck about).

There is a very useful and welcoming users group at https://groups.yahoo.com/neo/groups/ICOMR71A/info which has lots of helpful info and supportive members that you might want to join (free). It's a radio that is well worth fixing and (relatively) easy to work on if your temporary repair fails... 73

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    $\begingroup$ Welcome! Even if you have general advice and not a fix for the exact problem, it is appropriate to answer instead of commenting. Comments on questions are for asking the author to clarify the question. $\endgroup$ – Kevin Reid AG6YO Apr 18 '17 at 15:45
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    $\begingroup$ Thanks PeterH for that info. I suspected that after giving it a though thrashing and it responded by working again ....temporarily. One day I take it apart and do the pen test (tapping of components to see what one is bad) and checking the solder joints. Just got to find the time. BTW my name is also Peter as well. Cheers $\endgroup$ – Old_Fossil Apr 19 '17 at 4:49

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