Date: Sat, 14 Nov 2015 08:28:13 +1030
From: "Leigh Turner" <invertech@frontierisp.net.au>
To: <amps@contesting.com>
Subject: Re: [Amps] SPE 1.3K-FA and FTDX-5KMP
Charly, sadly there's an over-hyped obsession out there about Tx purity and
associated IMD specs for ham rigs....
Having said that many current SS amp offerings are poor performers in this
regard when driven to their rated PEP output :-(
Leigh
VK5KLT
### Leigh, the yaesu FTDX-5000MP uses a PAIR of VRF-1511Gs. They are the
170 vdc rated version of the MRF-151G..... ( 50-60 vdc rated).
## Now comes along SPE..with its 2.0K...running a whopping 2 kw pep output
from
just SIX MRF-151Gs. Now if SPE can achieve 2000w pep from 6 x devices, then
yaesu should be able to get 666 watts pep from 2 x devices. Can you
imagine the
FTDX-5K running 666 w pep out ? Well it would fare a little better than
the SPE junk.
## at least yaesu, and also the SS in the ARRL handbook, both used VRF-151Gs.
SPE didn’t even use the correct version of the 151G. The SS devices usually
fare a
lot better with higher voltages, with reduced imd being the result. If folks
want to
run high power on ssb, then at least take advantage in the latest and greatest
in
technology..and use the 170 vdc rated VRF-151G. doesn’t cost anymore
than the MRF-151G. The VRF-151G has been out for several years now...
its old news really. Perhaps SPE didn’t get the memo ?
## Like I mentioned b4, that SPE 6 x MRF-151G amp is a 600-750 watt pep
output max amp on ssb, that’s it. 2000w pep out from it would be 4 steps
below an imd garage truck. And no, the FCC etc, don’t regulate crap IMD
on the ham bands. No specs, no regulations pertaining to IMD, be as wide
as you want, as long as its within the ham bands etc.
## yaesu in class A..... driving any of the 3 x spe amps... to rated output =
IMD garbage. But folks like charly say they only look at one spec... rated
pep
out on ssb.
## BTW, if you look through the online SPE manuals, they say not to use
speech processing,
since this increases the duty cycle on the ss amp..and it will cook. (it will
also increase the average power in the
imd products, so the imd will then sound even louder).
## No folks, SPE didn’t get it right. They are selling you a bill of goods.
End of story.
Jim VE7RF
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