[Amps] SPE 1.3K-FA and FTDX-5KMP

[Jim Thomson]

Date: Fri, 13 Nov 2015 00:27:52 +0000
From: Charles H <k4vud at hotmail.com>
To: Richard Solomon <dickw1ksz at gmail.com>, "amps at contesting.com"
<amps at contesting.com>
Subject: Re: [Amps] SPE 1.3K-FA and FTDX-5KMP
Message-ID: <BLU182-W567DF91EBF085FB1F4BD9AF7110 at 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