[BC] How would you build it?

[Ira Wilner]

I'd start out with LDMOS devices.  And with digital RF & envelop generation
you may very well be able to get away with convection cooling if you don't
make the box to darn small.  I hate those wind tunnel high speed muffin fan
transmitters required for the small surface area heat-sinks squeezed into 2
RU cabinets. If space saving is critical you might as well go for water
cooling.  One of the shortcomings of SS designs is the need to keep the
output match very close to 50 ohms to avoid combiner mismatch and excessive
dissipation in their hybrid load terminations.  Fortunately for only 1 kW AM
you can probably use a single PA or at worst a pair of combined push-pull
PA's.

---Ira

-----Original Message-----

 From: robertm

Linears present their own problems beyond efficiency when used for AM. If I
were building a custom TX it would be solid state, use a mix of PDM and PSM
modulation. Have DSP envelope and IM correction. At 1KW I would avoid fans.