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BC-348 receiver help.
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January 27th 04, 04:13 AM
Mike Knudsen
Posts: n/a
In article ,
(N2EY)
writes:
2) The BC-348 B- (negative high voltage) is *NOT* grounded! It must be kept
isolated from ground in the power supply, unless major modifications are done
to the receiver. The receiver will work, sort of, with B- grounded, but it is
not recommended.
Right. The B- must be fed thru a filter choke, whose toehr end delivers it to
ground. The negative back bias developed across the choke is used to bias the
audio output tube's grid negative. Its cathode is straight grounded, so if you
run without this choke and B-, the output will draw excessive current and
distort.
That choke is in the same sealed case as the output transformer.
A question for the poster I'm responding to: Is that 220 VDC max including the
choke, or just from B+ to chassis ground? I'm assuming the whole thing (choke
included). --Mike K.
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