[AMRadio] Wanted Used Commercial AM Transmitter

[Radra]

Hello everyone.  I am new to this list, so thought I would briefly introduce
myself.  My name is Lyman Hays, K7LH.  I am an electrical engineer in
practice for many years.  My primary field of interest is RF design below 3
GHz.

In viewing the archives, I see names I recognize from the
Central-Electronics mail list.  To them I say "It's nice to see you again."

For one of my personal projects, I want to acquire one or more AM
transmitters I can experiment with.  So I am looking for transmitters of the
type used for AM broadcasting.  Want something in the 500 to 2000 Watt
range, preferably 1000 Watts (so I can use my existing attenuators and loads
and single phase power).  The transmitters must be all solid state. Typical
examples include: Harris SX-1A, Gates One, Armstrong 1000B, Omnitronix AM
1000A, etc.

My interest in these transmitters is two-fold.  First, I want to study
efficiency and linearity aspects of pulse duration modulation, results
perhaps leading to improved amplifier designs.  Second, I want to evaluate
the task of converting solid-state AM transmitters for ham use.  I
understand some PDM designs impose frequency limitations due to the
relatively slow switching speed of the power transistors.

I suspect the best place to find used transmitters may be at radio stations
who are surplusing gear, but I don't know of any efficient way to contact
them.  Does anyone have any ideas here on how to obtain used AM
transmitters?

Lyman