Shouldn't be too difficult to come up with the brute-force answer, but
I have to ask: Why?

That is, why so much power? And why 80 meters? I'd think you'd want
to use a higher frequency so that the antenna would be easier, and if
the balloon is aloft and line-of-sight, even a watt should be more
than enough to hear it loud-and-clear. Sending up an amplifier and a
power plant that will run it at 10 watts output will take quite a bit
of balloon displacement. I think it may be worth asking some
system-design questions to see if he can reach a more optimal
solution.

Cheers,
Tom

Allan Butler wrote in message news:mRmEb.595184$Fm2.545419@attbi_s04...
Hi there.

Another Amateur that is involved with volunteering with schools and such is
looking at launching a baloon with an HF transmitter on board. The band of
operation is 80 meters. He is looking at some type of a beacon that will
send data via BPSK modulation and needs 10 to 20 watts of transmit power at
the output port. For an input to the unit he has 0dBm or 1 milliwatt of RF
at the operating frequency.

This looks like it would require 40 to 43 dB of gain to get to the level
that he needs for output.

Does anyone have suggestions of places to look on the web for application
notes and/or schematics for amplifiers along these lines?

I have done some searching on Google and found a few things but most of them
take inputs of 30dBm or so and only take that level up to 40dBm. He still
needs to bridge the gap from 0 dBm to 30 dBm in that instance.

Any information that you can help with is greatly appreciated.

Al Butler
ka0ies