I have been using home brew SS amps at my 8P5A station exclusively for the
last two years. The flexibility and increased operator efficiency are a
big advantage. As such, I am a true believer for this use case.
However, I am not sure that they are a better solution than single band amps
for the pure Multi Multi. With the operating efficiency of instant band
change largely moot, there is less to offset the down sides. With
potentially 6 full power signals at once, and in band receivers, signal
cleanliness is a key factor. The LDMOS parts simply do not have the IMD
specs of tubes. K3LR has supreme engineering skill and may be able to
design around some of these limitations on a per band basis. Plus, the
predistortion techniques are very exciting, but not limited to SS amps.
Overall, if it can be done, K3LR will find a way, but I would not be sure
that current off the shelf solutions would be the cleanest for M-M.
Overall, I think creative engineering can help with IMD, but it is not
standard today. Also, the parts have come a long way, but the LDMOS
transistors are not as rugged as tubes in most fault situations. If kept
cool, reliability will be fine with well matched antennas, but will not be
as tolerant of antenna system faults. Without the need of the flexibility
of instant band switching, I am not certain that SS amps are a better
option than single band tube amps for the dedicated M-M station.
Situations other than M-M can be good matches for SS Amps, but the need for
a well controlled environment and well matched antennas is still there.
Just to be clear, I am not claiming to have solved any of these problems,
just that I feel the advantages outweigh the risks in my case. YMMV
73, Tom W2SC 8P5A
-----Original Message-----
From: CQ-Contest [mailto:cq-contest-bounces@contesting.com] On Behalf Of
Jeffrey Maass
Sent: Friday, December 22, 2017 10:13 AM
To: cq-contest@contesting.com
Subject: [CQ-Contest] Solid State Amps in Multi-Multi Stations?
Is anyone using solid-state amps at a competitive multi-multi station?
Which? Any problems?
73, Jeff K8ND
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