In a message dated 9/9/2006 8:28:21 P.M. Eastern Standard Time,
carlseye@tampabay.rr.com writes:
I have been working on an amp, fl2100B , and see something I can't
believe.!! the amp has 2 ea. New chinese type 572B's.
I have two output meters, both WM1 auteks.; With about 60-80 watts
input I'm seeing almost 1 kw. *output*. Is this anywhere near logical
?? The HV is about 2200-2300 under load. !! It just doesn't seem
possible, and I've never seen anything like this
before !!!
I've worked on many other amps ( similar ) and have never seen
anything like that much output.!!
BUT, I've never used *chinese* 572'B s either !!
Do any of you have any spec's that might differ from the
U S. ( IE ) taylor ,l or other mfrs. Specs as to the gain factors
between the US and chinese specs'?????>
I'd appreciate any info anyone might have !!!!!
carl / kz5ca
Carl, What band are you seeing this kind of output? I had a WM-1 in the
past and I would not say they are the most accurate meter I have ever owned,
in
fact far from it. There are adjustments to "calibrate" it, but it tends to
be a compromise along the bands. Likewise, I have never seen this much power
from a pair of 572B tubes, but I have used MANY of the Chinese 572B tubes in
my 6 meter conversions and they DO out perform ANY other brand of 572B
including Cetrons. Though my experience with them is only on 6 meters which
is
the upper limit of which they will work, there is no doubt that the Chinese
tubes make more power than others. I would NOT even attempt to use a Russian
tube on 6 meters! Though I doubt the Chinese tubes have the quality control
that the Cetrons did, I could imagine that some tubes may have more gain than
others and perhaps you have gotten a "freak" pair that makes more power than
most. At one time I did see about 800 watts out of one of my 6 meter SB-200
retrofits on 6 meters and I was amazed at that. I obtained that with every
bit of 100 watts of drive. You mention that you see this with only 60-80
watts
of drive, that makes me wonder. If you could possibly retest the output
using another meter I would be curious to see what reading you get. When I
tested the output of my 6 meter SB-200 conversions I did it into a Bird dummy
load using a Bird 43 meter with a KW slug. I also used another meter to see
what it said. Other meters were always close to the Bird numbers by single
digit percentages. Now, it has been almost 3 years since I have used a set of
Chinese tubes in an SB-200 on 6 meters, and perhaps NOW they have even more
gain then they did then. I don't mean to doubt your claim, but I would see if
another meter tells you the same thing. I do believe a test into a dummy
load with more than one meter is in order. Report results if you can do such
a
new test. BOTTOM LINE: I do agree that the Chinese tubes have more gain
then other types of 572B, and maybe they have just improved their product.
Could be? 73 Lou
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