June 26th 04, 10:56 AM
|
|
|
On Fri, 25 Jun 2004 23:28:12 -0000, (Dave Platt)
wrote:
According to a talk I saw recently, commercial television broadcasters
have moved almost exclusively to solid-state RF amplifiers for their
newer stations. No one set of transistors can provide thenecessary
power, so the amps use a large number of smaller modular amplifiers
operating in parallel - I think the basic "brick" we were shown was
capable of a couple of hundred watts. I haven't seen any ham-band
amplifiers using this modules-in-parallel approach, although I'm
sure one could be built.
In broadcasting, the station is usually operating on the same
frequency all the time, so simple Wilkinson dividers/combiners (which
are frequency specific) can be used, which effectively isolates the
modules from each other, when one module fails.
However, a ham linear amplifier is typically required to operate in
the 1.8-30 (or -54) MHz frequency range, which complicates the
divider/combiner issue.
Paul OH3LWR
|