Date: Fri, 13 Nov 2015 00:27:52 +0000
From: Charles H <k4vud@hotmail.com>
To: Richard Solomon <dickw1ksz@gmail.com>, "amps@contesting.com"
<amps@contesting.com>
Subject: Re: [Amps] SPE 1.3K-FA and FTDX-5KMP
Message-ID: <BLU182-W567DF91EBF085FB1F4BD9AF7110@phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
I do not know anything except that when I ran my Yaesu FT-1000MP Mark 5 at 40
watts to drive my tube amplifier in Class A, I burned up that radio so well
that two other very smart men could not fix it, including Yaesu London.
That orange button is not something to be touched. 73, Charly
P.S., the defenders will arrive on schedule, but I say, why risk it? The
Elecraft Lovers Club started this hurrange about transmitter purity. In fact I
read the very first message of what has spread like psoriasis where a ham
demanded in one post that anyone not running a K3 should have their contest
scores reduced. No kidding.
## I own TWO yaesu FT-1000MP- MKV and yes, they are blazing hot in class A.
I only use it for brief testing. take the lid off and u will see in 3 secs
what the problem is. there is NO air going past heat sinks 1+2. I modified
mine by installing a curved sheet of teflon on the yaesu squirell cage
blower..then more air out the heatsinks but still not enough. You almost
have to seal the top gaps between each heat sink, then suck the air through the
backs of all 4 x heatsinks with an external blower.
The fix for the mk-V is to either reduce the idle current, when in class A..
way down from the OEM 10A CCS, OR increase the idle, when in class AB mode.
10A x 30 v = 300 watts. I mean u don’t need to suck 300w
ccs, just to put out a clean..max po of 75 watts...= 225 watts diss...and
worse if running say just 25-30 watts out...and still worse if keyed, but no
drive applied to the mic. It sucks just 2 A when in class AB mode.
Between 2A and 10A of idle current..there is a happy compromise.
## The k3 is a joke on SSB TX. Lousy IMD. sure it’s a superb CW xcvr.
But –29 db pep for IMD3..... gimme a break. these guys still don’t get it. (
both elecraft and its groupies / fan boys)
## it will be a sad day when Expert goes outa business....and leaves
thousands of owners holding the bag, with non existent parts, and no
schematics. No schematics, then no sale...from me anyway.
2 kw pep out on ssb.....from just 6 x MRF-151Gs is 100% pure looney tunes.
And when u operate any of those SPE amps in the mid or low power mode, they
just reduce the voltage..so eff doesn’t
go totally into the crapper. Problem is... the imd gets worse with reduced
voltage, so its one step forwards..and one huge step backwards. 6 x MRF-151Gs
is a max 750w pep out setup on ssb...
and just maybe 1000 w pep, if u push it.
## their imd tests is flawed anyway. And just cuz u reduce ur 200w rig down
to 30 watts to drive it, doesn’t mean u will hit an imd sweet spot on the xcvr.
100w xcvrs typ hit their imd sweet spot around 30w.
200w xcvrs hit their imd sweet spot typ around 100w pep. having said that,
the K3 is a nice clean SSB xcvr..when run at 30 watts pep. My buddy uses his
k3, run at 30 watts pep out on ssb, to drive the
arrl 2 x VRF-151G hb SS amp, to 200w pep out. Run that way, it’s a clean
200w pep out. he uses a 6db pad between k3 and hb ss amp....since the arrl
ss amp only requires 7.5 – 8.0 watts to drive it.
## will that SPE 2 kw amp even run 1500w out on RTTY...don’t think so, it
will switch down to the mid power mode.... until u cook it again, then its down
to the lowest of the 3 x power levels.
## so nobody makes a 1.5 kw RTTY SS amp. Wake me up when they do..and
prepared to have deeeep pockets.
## I can see why a real high powered 1.5 kw CCS RTTY SS amp will cost a lot
of $$. You require a 3 kw ccs power supply...since the rf deck only runs 50%
eff. Then u need a 1.5 kw CCS rated auto tuner, so the ss amp doesn’t blow
its brains out. Then u require a myriad of 1.5 kw CCS LP filters, enough to
cover all the amateur bands... + 6M.....plus a method to switch them. You
don’t require the myriad of LP filters + 1.5 kw auto tuner with any tube amp.
IF the tune + load caps are carefully marked from 0-100 across 180 degs of
a large diam skirt, like with a jackson bros 6:1 ball drive and mating skirt,
then changing bands becomes a snap. Just dial
up the pre-sets. A buddy installed just that on the tune and load on his
SB-220..works superb.
## IMO, SS amps are not quite there...yet. Not ready for prime time use..at
least with the latest offerings. When somebody builds a 1.5 kw rtty SS amp,
elaborate cooling syttem, and enough large devices to run low imd, then Im in.
Those freescale devices are relatively inexpensive.....so why don’t they use
more of the biggest ones offered, and the TX IMD can easily be dropped through
the floor. As the current ss amp offerings are all on a par with a 1970s
sweep tube amp.
Jim VE7RF
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|