This is kind of a trivial question, but is interesting to me. I got to
wondering what kind of output power I am getting from my old wheezer
Sideband Engineers SB2-LA final. There are several aspects concerning this
that made me start to wonder.
One is that the manual says the final is rated at 1kw for SSB. I would
assume that I could expect to get that out during a very short key down
interval of a couple of seconds or so. When loading, I do get an indicated
input of about 900w with the plate meter (again during a very short
interval).
Then comes the fact that the tube lineup is six 6JE6s. I'm reaching way
back for the next part, which is that when I was last really involved in the
ham business, the 6JE6 was a relatively unknown TV sweep tube. I don't have
access to tube charts, but, the tube looks a lot like a 6146. If I remember
right, the 6146 is breathing heavy at the 90 watt level. Let's assume the
6JE6 is similar. Well, 6 x 90 = 540 watts. So, how do the six 6JE6s get
bumped up to 1kw?
Ok, long about now, we are going to hear about the concept of duty cycle,
and this could well be the answer. We all know that small tubes can really
be pushed in pulse type applications. SSB with PEP concept is a variant of
this concept. Is this how they do it?
To further confuse the issue, I see an honest indicated 300w when I tune the
final on my 'tenna tuner power out meter. I know some of these are damped,
and that they lag on voice peaks. So, what real power out am I likely
getting when I'm seeing 300w peaks? With a downhill run, and the wind at my
back, what should this unit be capable of in terms of output PEP power? Is
the 300w PEP peak about the best it should do?
73 de Ron, K5BDJ
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