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.
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