Hi Jeff,
I don’t think right now is the right time to make such an evaluation.
Consider the state of the market.
LDMOS technology is now making itself present in the amateur radio
mainstream. This is the future of solid state. Before LDMOS there was
absolutely no way for solid state and valve amplifiers to be equivalent.
However these new devices are very rugged and can withstand the abuse and
“oops” you will see in the heat of a contest.
We are now seeing viable designs from mainstream amateur radio
manufacturers -
FlexRadio is about to release its PowerGenius XL amplifier which is
currently in beta testing (full disclosure - I am a FlexRadio tester). This
amp is designed and built by 4O3A signature and offers full SO2R out of the
box. It also has a vapor chamber heat sink as well as MEffA which adjusts
the amp bias and voltage for maximum efficiency, and signal quality. This
means better signal AND duty cycle. This amp is dual LDMOS.
Elecraft is also introducing the KPA1500 which is a dual LDMOS design as
well. I don’t know specific details but this amp should be good as well.
Acom has one, and others are going to be debuting theirs - Alpha/Dishtronix
is rumored to have one under development and I wouldn’t be surprised if
icom or another manufacturer comes out with one. Linear amp UK has one
under development.
SPE has solid state amps but I’m disappointed in the LDMOS designs because
they only use one device, not two. I had a SPE1.3K-FA that struggled to
keep up during CQWW phone. Forget about RTTY. It would drop me back to 800
watts. RemoteHamRadio runs theirs around 1000-1100W because of the signal
quality issue. You also can’t run that amp at legal limit or even 1300W for
an extended period with highly processed audio or RTTY. It will alarm and
shut down. The 2K-FA is older technology and while it may do better duty
cycle it can’t do it the same as 2x LDMOS and the signal purity suffers.
The 1.5K-Fa uses one 1800w device but I feel that won’t stand up to extreme
contest duty, especially with RTTY.
Tim brought up signal purity - I would say that this warrants waiting as
well because adaptive predistortion is the new thing that can produce
signals MUCH cleaner than any tube amp. This is where a sample is fed back
to the transceiver and via DSP the signal is “predistorted” to cancel out
any distortion in the signal. This is already available in Anan
transceivers and is coming to flex and maybe Elecraft. Both flex and
Elecraft amps have the predistortion port.
B26-PA is also a good choice and inexpensive. 2xLDMOS. It is a kit however
and requires some assembly skills.
So I would suggest waiting a few months before making a decision.
Ria
N2RJ
On Sat, Dec 23, 2017 at 9:03 AM Jeffrey Maass <jmaass@k8nd.com> wrote:
> Is anyone using solid-state amps at a competitive multi-multi station?
>
>
>
> Which? Any problems?
>
>
>
> 73, Jeff K8ND
>
>
>
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