[Amps] Solid State vs. Tubes

[Dan Levin]

NB: I am hard at work (with many others) on a solid state amp that will be
reasonably priced, very robust, and buildable by any ham who wants to own
one - so I'm biased.

That said, the big problem with the Tokyo Hy-Power amps is that they aren't
built for high duty cycle work.  If you take a look at the inside of the
2.5Kfx, you will see a copper heat sink roughly 5" tall and 13" long that
runs down the side of the chassis, and has air flowing vertically across it.
There is just no way that heat sink is going to dissipate anything like 1.5
KW (at 50% efficiency, they spec the amp at 3 KW input), especially with a
single fan providing airflow for the entire system.  That is why they only
rate the amp for 1 KW RTTY for 4 minutes - vs. 1.5 KW key down forever for
the Alpha.

For high duty cycle work like CW or RTTY contesting, you need a solid state
amplifier with much more cooling capacity than the 2.5Kfx has.  Until
someone builds one, solid state amps like the 2.5Kfx will be very useful in
some situations, but will not replace tubes just yet.

                  ***dan, K6IF