I’ve been using it for about a year now, including some all weekend dual CQ
efforts. No problems. The TopTen A/B relays take just under 30 ms to switch,
so I program in 60 ms of delay between PTT and keying. The relays have about
80dB of isolation, and in combination with the regular SO2R filters gives me
plenty of isolation. I do need to finish the harmonic stubs/filters for the
lower bands where the 2nd harmonic can be a problem.
I knew once I got this working that Elecraft would come out with a full power
amp ;^) But the setup would be perfect as is to just drop the KPA1500 in
place without the splitter/combiner (or maybe 2 KPA1500s!!). I would bet that
the control systems are similar to the KPA500 and they are plenty fast to
follow SO2R switching. So not a wasted effort.
Ken K6MR
From: WT2P - CJ Johnson<mailto:fredwt2p@gmail.com>
Sent: Friday, April 28, 2017 10:04 PM
To: Ken K6MR<mailto:k6mr@outlook.com>;
amps@contesting.com<mailto:amps@contesting.com>
Subject: Re: [Amps] W6PQL Designs
That's an interesting way of doing it... Have you run into problems with the
rapid switching that occurs when you're doing SO2R? (are you using it in a SO2R
rapid switching environment?)
There's some data to be gathered (on my end) but it's still interesting...
On 4/28/2017 11:51 PM, Ken K6MR wrote:
Yes. I have two KPA500s. I use the splitter to drive both of them on the same
band, and the combiner to put the two outputs back together. I also have a set
of relays that switch the assembly between the two K3s. I have an Arduino that
handles switching band data, keyline, etc.. It uses the Tx Focus from the u2R
to make the amps follow the active radio. The amps are in the closet, I just
watch them using the Elecraft remote programs. Ditto for the tuners, one per
radio.
All of my antennas are fine on cw/rtty, but the 80m antennas get squirrely
above 3650. I hardly ever operate phone so it doesn’t affect me. The tuners
will make them tolerable up to 3750 or so. The KAT500s are good to 1000W at
3:1. Good enough for me.
As long as the tuner will handle it, the feedline losses are so low on 80 that
it’s not worth changing anything. 3 or 4 to 1 isn’t going to break anything
even at 1500W with normal sized coax.
Ken K6MR
From: WT2P - CJ Johnson<mailto:fredwt2p@gmail.com>
Sent: Friday, April 28, 2017 9:18 PM
To: k6mr@outlook.com<mailto:k6mr@outlook.com>;
amps@contesting.com<mailto:amps@contesting.com>
Subject: Re: [Amps] W6PQL Designs
Ken-
Did you get the Combiner/Split for an existing amp?
I'm looking at obviously not duplicating the 4O3A design in SO2R amps, and have
been resigned to the fact that i'll probably operate two amps for SO2R... but I
am looking at building at least *one* amp that is SS for my shack. That is the
pinnacle here, of finally operating an amp that performs well in a contest and
being able to say "I built/assembled it myself". And being able to troubleshoot
any faults that may occur.
There's been a lot of talk about LDMOS amps, and I'm genuinely curious... I
have resonant ants for 40/20, but on 80, my seasonal antenna is fairly resonant
but narrow bandwidth (3.5-3.68) before the SWR jumps. I've seen some videos of
the LDMOS variant amps taking a 3:1 rating (obviously not at RTTY levels) but
it has piqued my interest. Even my 76PA has "appeared" to tolerate my momentary
excursions up to 75M, but I know that the reflected power is just eating away
at the tubes. Probably even more so with transistors.
I know the answer is to get resonant antennas, which I have done.. I'm
impressed with my Alpha 76PA in the fact that it has dealt with me at 3AM
mistuning the thing and it still works like a racehorse.
On 4/28/2017 11:00 PM, Ken K6MR wrote:
I bought the combiner/splitter assemblies made by W6PQL for my dual KPA500
project. High quality boards and they work great. The amp pallets look like
they are the same high quality. I’m just too lazy to take on a project like
that.
He did an update on the filter design that has better harmonic suppression for
the high power model.
Ken K6MR
From: WT2P - CJ Johnson<mailto:fredwt2p@gmail.com>
Sent: Friday, April 28, 2017 8:37 PM
To: amps@contesting.com<mailto:amps@contesting.com>
Subject: Re: [Amps] Amps Digest, Vol 172, Issue 92
Can we get back to the topic(s) at hand, namely building/repairing amps?
I, for one, am very curious about the new SS amp line(s) coming out and
researching as much as I can about the W6PQL designs and would like to
hear more about the merits of that design and some advice for budding
builders who want to experiment along that path.
Or is this going to devolve into an online version of 7.200?
Thanks,
WT2P
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