Greetings to all,
Last week, I received a case (10 tubes) of new Chinese 572B tubes
from a distributor that I have bought tubes from for over ten years. These
tubes were new, from the latest production. I plugged two into a SB-200 and
was disappointed to see a bit less than 50 % of the expected power. I tried
another pair and got the same results. I went through the entire case and
found them all to be way, way, down in emission, but, I must say, they were
extremely well balanced. HI Hi
I had a pair of 572B's, from the same source, that I bought about
two years ago, in another amp. I plugged them into the test amp and got the
normal, expected, output. The entire case of new 572B's went back to the
distributor. I wonder if they mixed up some low Mu tubes with their Hi Mu,
572B's at the factory.
There was some discussion about the Svetlana the 572-160, in one
post. They are excellent tubes for audio work. They have, basically, the
same internal structure (large graphite anode) as the 572B, but, without a
plate cap, they would not be an simple job to install them in an SB-200,
FL-2100, or Ameritron amp. But, for the AM'ers, they make a great
modulator tube.
73 de Lon, K5JV
Lon W. Cottingham
1110 Golden Bear Ln.
Kingwood, TX 77339
281-358-4207
281-795-1335 Cell
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