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

[Jim Thomson]

Date: Sat, 14 Nov 2015 08:28:13 +1030
From: "Leigh Turner" <invertech at frontierisp.net.au>
To: <amps at 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