Have you tried a different set of tubes?
Paul
PAUL HEWITT
WD7S PRODUCTIONS
QRO HOMEBREW COMPONENTS
http://wd7s.home.att.net
With Drake L4-B SN #1962 after 5 min of
normal operation audio becomes
distorted, very bad. This problem still
exists when amp is driven with
two different xcitrs and two different
low SWR antennas. Well grounded.
With Key down the plate current
fluctuates suddenly between 400-500 Ma
erratically and irregularly. Spurrious
radiation is getting into
phones. Replace with another L4-B
using two same antennas and with
same xcitrs, and there is no
problem..What are possible problems with
amp SN# 1962 ??
Tnx, Dick
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