"Walter Harley" wrote in message
...
"Paul Burridge" wrote in message
news
On Wed, 05 May 2004 20:13:01 -0400, Ken Scharf
wrote:

Mosfets in the MRF5xx series (511, 521 for example) have been used
up to the 10 meter band with good results. A pair of them can give
at least 50w pep output. Depending on the input/output circuitry
used and the transistor they require 12-28v power supply. Layout
is somewhat critical.

THanks, very interesting. I wonder if anyone's tried paralleling up
half a dozen of 'em for more power?

Modern commercial radio transmitters (including FM band, 88-108MHz) by,
e.g., Harris use MOSFETs. So clearly it is possible to get up to 25kW. I
believe they also use them in 100kW AM band transmitters. A bit of
meandering on Harris' web page will tell you more.


Their AM transmitter combines the outputs of 60 some modules to get the
instantanous PEP they need. All modules are fed the same square wave signal,
and modules run class E (I think). They don't say what the sampling rate is,
but I would guess ~20 KHz. There is a WLW related web site that has more
info than the Harris site. If I run across it again, I will post it.

Tam