[Amps] amp tubes

[Gudguyham at aol.com]

In a message dated 9/9/2006 8:28:21 P.M. Eastern Standard Time,  
carlseye at 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