[MRCA] Working on an old BC-342

[Ray Fantini]

Leaking screen grid capacitors will hurt sensitivity, leaking capacitors in the AVC bus will cause distortion and overloading. Small leaks can make a big difference. Also leaking capacitors can turn into shorted capacitors if you don't address them.
Remember to pack away a high impedance speaker with the radio, they don't like being connected to a four ohm speaker.

Ray F/KA3EKH


From: mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net> On Behalf Of David Olean
Sent: Monday, February 17, 2025 1:22 PM
To: J Mcvey <ac2eu at yahoo.com>; Military Radio Collectors Association <mrca at mailman.qth.net>
Subject: Re: [MRCA] Working on an old BC-342



Hello folks and thanks for the advice on the BC-312/342. The oil filled caps in the BC-342 are rectangular and soldered together.  Luckily they are all located in HV  B+ lines and are not in the AVC circuits.  They are working for now in my radio.  I will try the big soldering iron idea first to remove the covers. If that does not work very well, I can saw the cap apart just under the top cover. That will require removing all of the caps though.  Once sawed in two, the top cover can be re installed on the capacitor body and the only difference will be that it is a bit shorter.

I did dis assemble the radio by unsoldering all of the RF coil and the oscillator compartments and swapped out all those Micamolds that were in the AVC line in those boxes. I put the radio back together and the set really took off. As the tubes warmed up, I was greeted by a very ample supply of background noise on all bands.  The set is not hot as a two dollar gun. I checked the 6 dB S/N ratio at 5 MHz and saw 0.26 microvolts for a 6 dB jump in audio. A 1 microvolt signal is now loud on all the bands.

My plan is to give the radio to my grandkids and hope they get a kick out of snooping around on the air waves.  At a minimum, it will get some attention.

I also did some snooping around and found a very early article by George Grammer back in Septemer of 1946 on the pages of QST. His article is great and covers many items that need work to improve the radio. Sadly, many subsequent articles are around that have plagiarized the original. Some parts of the texts are copied almost word for word.  Pretty sad. There is never any ref back to George's original work.

73

Dave K1WHS
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