>>Congratulations! But I suspect you can squeeze another 5-10% efficiency out
>>of it with more work. I mean, we're never satisfied, are we?
>>
>Efficiency is very hard to measure accurately, and the potential errors
>mean that he might already have another 5-10% in fact... or it might be
>5-10% worse.
Correct. I've not a real good way to measure plate voltage. I have a
30KV probe, but that only gets me in the ballpark of a KV or so.
After I got the amp up and running, I realized that the meter in the HV
supply was more accurate than my 30KV probe. The guy who built it did a
decent job. My plate voltage under load was not 5500 as I had read from
my probe, but more like 5300. If this lower voltage is correct (which I
am assuming) then my efficiency is better than I reported.
Dick said I should get 50 to 55% on 10m. Well, that's what I've gotten!
Funny thing is efficiency doesn't really matter a whole hill of beans in
the end though. Let's see, we've neglected PS efficiency, coax losses,
bandswitch losses, etc. At high power levels even .1 or .2 of a dB of
loss in something can mean 50 to 100 Watts of power lost (depending upon
actual output power). I realized this practically, when after hooking up
the amp to my antenna bandswitches, I noticed less power out. It only
makes sense! So what does efficiency mean anyhow? 5% isn't going to
make that much difference. IMO, as long as you get the power and gain
you want and your efficiency is in the theoretical neighborhood that's
all that's important (I guess that comes from the fact that I used to
design amplifier systems with 7% efficiency considered good!).
I agree with Dick that if your tank circuit is too lossy efficiency will
suffer. A lossy tank circuit could create a lot of heat and other
problems. I also agree with his input circuit comments. However, my
input circuits all have a Q of 2 or better and I don't think there is
much I can do with my tank - or at least much I WANT to do!
Hey, after a year and a half of on/off work on this thing, I am PLEASED!
So I don't want to mess with it any more. If it's not broke.............
And I am getting GREAT signal reports from it. Ran Europe for an hour
on Saturday on 10m and everyone said my signal was broadcast quality.
They say the audio is great. So I ain't messin' with it! Hi!
73,
Jon
KE9NA
--------------------------------------------------------------------------
Jon Ogden
jono@enteract.com
www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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