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Re: [Amps] RF2K+ LDMOS linear

To: "Ken K6MR" <>, <>
Subject: Re: [Amps] RF2K+ LDMOS linear
From: "Jeff AC0C" <>
Date: Sun, 4 Jun 2017 23:34:30 -0500
List-post: <>
For me, especially with RTTY contesting, the capability of running this amp on a So2r basis should not be assumed to be workable until it's actually proved. This gets back to my main point. The gee-whiz it will be perfect buzz on a lot of tech really needs to come with a list of disclaimers to cover the exceptions and restrictions. But they never do; meaning the only way to really get a handle on them is for someone to get one and give it a hard workout. That would at least be one solid data point.

And you can't really make a compare to the Elecraft stuff - the same issue confronts the KPA1500 (it's an unknown new entity - until it's proven in combat). However they have a proven track record of making a decent product and improving it when there are issues. These other various guys who want to get into the amp biz are unknown entities by comparison and while they may build perfect products and have perfect support, to my thinking until that's actually proven it needs to seen with a skeptical eye until proven otherwise.


-----Original Message----- From: Ken K6MR
Sent: Sunday, June 04, 2017 11:19 PM
Subject: Re: [Amps] RF2K+ LDMOS linear

“And you need 2 of them for a serious So2r setup”

It’s pretty simple to switch one amp between the radios, so that’s not necessarily true. But the amp must be able to run pretty much key down for the whole contest.

My dual KPA500 setup runs full output continuously on RTTY (switched between radios) with only occasional maximum fan activation. I’m hoping the same will be true of the KPA1500.

Ken K6MR

From: Jeff AC0C<>
Sent: Sunday, June 4, 2017 8:34 PM
To:<>; Kevin Stover, AC0H<>
Subject: Re: [Amps] RF2K+ LDMOS linear

Sorry for the confusion.  I was thinking of a pair for So2r.

Each kit is over $3K - not including delivery or local parts sourcing.  Call
it $4K as a round number.  And you need 2 of them for a serious So2r setup.
As amps go, I don't see the price as a primary issue.  Serious runs by
serious contesters are the issue in my mind.


-----Original Message-----
From: Kevin Stover, AC0H
Sent: Sunday, June 04, 2017 6:22 PM
Subject: Re: [Amps] RF2K+ LDMOS linear

All fine and good but where on God's green earth did you get $8K?
The SPE 2K is $8K but were not talking about that amp (^^^subject
line^^^). We're talking about the German amp kit which sells for a
kilobuck LESS than the AL-1500 all in.

Without the auto-tuner the kit sells for about $1K more than that pretty
Eimac 3CX1500A7 in the AL-1500.

On 6/4/2017 12:19 PM, Jeff AC0C wrote:
I'm with Steve here.  The old saw of "build a better mouse trap and the
world will beat a path to your door" is almost always false because it's
hard to believe the hype surrounding stuff.  If an amp maker wants to
crank up the sales in the US of their amps, by far the best way would be
to put it in the hands of someone who has a good tech reputation in the
community, can give it a serious contest workout and who also has the
ability to do a basic IMD test.

There are many folks of that description.  Before I shovel what is going
to be nearly 8K into a box, I really would feel a lot better if I heard
that they lived through a couple of contests over at W3LPL, etc and Frank
said they hummed along fine.  I'm using LPL as an example here.  My point
is advertising and social media and endorsements from guys in EU are a lot
less meaningful than a country local here in the US.

Made the exact same argument to a Chinese maker when he was trying to get
going but he unfortunately just could not wrap their head around the
marketing aspect of a product roll out.  The ham universe is pretty
small - and an endorsement by someone objective and authoritative carries
far more weight in this market than in others, especially given the huge
financial investment something like this involves.


-----Original Message----- From: Jim Thomson
Sent: Sunday, June 04, 2017 11:48 AM
Subject: [Amps] RF2K+ LDMOS linear

Date: Sun, 04 Jun 2017 07:58:54 -0600
From: Steve London <>
Subject: Re: [Amps] RF2K+ LDMOS linear

<I would not declare tube amplifiers dead until a legal limit, SS
amplifier repeatedly proves itself in serious contest conditions. I'm
not talking about the guy who casually makes 500 search-and-pounce
QSO's. I'm talking about the balls-to-the-walls, SO2R, all-band guy/gal
who operates close to 48 hours, running stations the entire time.
Mistakes happen under these conditions - ooops, forgot to change the
tornado tuner on the 80 when moving from 3700 to 3800, etc. Or, RF from
one amp gets into the other amp and fools it's microprocessor.

The only production SS amp that has come close to proving itself under
there conditions is the SPE line. Even they aren't perfect. See . That was an
SPE 2K. In all fairness to SPE, see . A pair of
SPE 1.3K's that worked flawlessly. (However, not at the legal limit.)

I would love to borrow a pair of these RF-Kit amps and put them to
serious use in one of my SO2R contest efforts.

Steve, N2IC

##  High swr, so what, amp kicks offline at some pre-set threshold.
They are already in use across rtty contests.  Fans  are
pwm controlled, so heat is not an issue.   Eff is high at 65-70%.
IMD is typ –40db pep..using the newer german made LP filters.
Mark tells me these amps are 100% duty cycle rated, all modes.
If they survive a rtty contest, ssb + cw should be a lollygog.

## You are right though...  send some off to contest sites..and really
on em for the weekend.   Tube amps  days are numbered, the writing is on
the wall.

Jim   VE7RF

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R. Kevin Stover    AC0H
FISTS #11993
SKCC #215
NAQCC #3441
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