>
>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.
My guess is they are talking about input watts.
>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.
Electrically, the 6JE6 is way different.
>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.
peak cathode emission has a lot to do with pep output.
>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?
You need a calibrated scope and hv multiplier probe to measure voice
peaks into a 50-ohm load.
>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?
>
I never measured one, Ron
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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