During the CQ 160m CW test we were attempting to use two radios so we
could listen on one and run on the other. It was working fairly well
until at one point we must have gotten too much RF into the 870's
antenna jack. The RX on the 870 lost most of it's sensitivity (read
this that we could only barely hear a couple stations on the band).
After several minutes of troubleshooting I determined that there was a
small bulb in series with the reciever that had opened. It looked like
it was in a socket, but it turns out that it was just soldered into a
plastic carrier that is surface mounted to the board. The investigation
also showed that the "RX ant" jack on the back has a similar bulb plus
resistor in series with it.... plugging the beverage cable into the rx
ant jack restored the 870's RX for the rest of the contest.
The location of the bulb is not very easy to get to without removing the
board (its under the back lip of the case) and i wanted to have the rest
of the rx checked out so i sent it to groton electronics for repair.
the technician there says the part is a new one and he didn't know when
he could get it, or even what the cost would be (it would be covered
under the warrenty anyway). In order to get it back on the air by the
ARRL DX tests he swapped the bulbs so now the rx ant jack doesn't work,
but the regular tx ant does. He is going to send me the bulb whenever
he gets it in.
I think it is interesting that they now build in protection like that, I
just wish the bulb was in a socket, or at least easier to get to.
--
ky1h@berkshire.net or robbins@berkshire.net
http://www.berkshire.net/~robbins/ky1h.html
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