I already answered this via a private email, but for
the record, I have had a 275 watt Matchbox since I was
a teenager. Bought it used. I have been running an
honest 1.5 KW into it for at least 20 years with loops
on 80 and 40. This, running Eu's from the East Coast
and now for CQP and SS, etc., from the West Coast. I
have also run 1000 watts continuous RTTY for contests.
I have never opened this box up since I got it. Just
keeps on ticking. I NEVER tune it with the KW into
it. Never tune it with more than 100 watts. Once
VSWR is at least under 3:1 (generally it is 1:1) I can
run my brains out on 80 and 40, full suds, without
blowing it up.
Bob
W1RH
--- Rick Karlquist <richard@karlquist.com> wrote:
> An historical note:
>
> Johnson sold a transmitter rated at 275W, DC power
> input.
> It was called the Valiant or something like that.
> I believe this is where the 275W came from (ever
> wondered
> why not 250 or 300?). This transmitter probably had
> an
> output in the neighborhood of 200W. Like my FT1000.
> During the heydey of Johnson, you got on AM and had
> 5 minute transmissions. Thus you can multiply 200W
> by a factor of 2 if you are transmitting 50% of the
> time
> for short periods and an additional factor of 2 or
> more
> accounting for peak to average for CW or SSB. Thus
> thermally, you should be good for 800W. You are
> also
> good for 800W in terms of voltage breakdown because
> 200W AM is 800W PEP.
>
> Rick N6RK
>
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