[Amps] Expert Amps 2K-FA: Any Opinions ?

Paul Christensen w9ac at arrl.net
Wed Apr 25 06:57:49 PDT 2012


> I would also be concerned about cooling (and noise) with that much
dissipation in such a small box.

I have the 1K version of the SPE amp.  Nice, compact and reliable design. 
If the League's QST product review is to believed, IMD performance is 
excellent for a solid-state design.

No contesting here but when using CW in say....a 2-3 minute exchange, the PA 
deck becomes quite hot and the fans are running "full tilt," resulting in 
what sounds like a jet engine.  That, together with output power that 
changes with PA deck temperature seems to be problematic with most 
commercial solid-state amps.  SPE does use a very well designed protection 
system.  In effect, a high-speed bus is created to kill bias to the PA 
transistors when one of about a half-dozen faults occur.

I like the amp for its instant-on, compact design, but I would never use it 
as a replacement for a good VT amp.  I saw the 2K amp recently at the 
Orlando hamfest and for folks wanting a solid-state amp, I think it's worth 
considering.  But if noise in the shack is bothersome issue, ask other 
owners about noise level with varying duty-cycle at full output power.

I believe the 2K version has a vacuum relay option that adds several hundred 
dollars to the purchase price.  In my 1K, its T/R frame relays were way too 
loud.  I ended up modifying the amp's logic for use with an Ameritron QSK-5. 
The interface between the two units is optically isolated and a schematic is 
shown on my QRZ.com page.  Much happier with this arrangement as it's fast, 
silent, and no truncation of keyed elements.

Paul, W9AC




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