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

To: Jim Thomson <>, "" <>
Subject: Re: [Amps] SPE 1.3K-FA and FTDX-5KMP
From: Charles H <>
Date: Tue, 17 Nov 2015 00:00:17 +0000
List-post: <">>
Leigh, with all the great rcvrs out there, I do not worry about my transmitted 
signal.   Whenever a ham has the urge to write or even worry about IMD, he 
should instead go visit a shut-in or a nursing home and cheer people up.  73, 

> From:
> To:
> Date: Mon, 16 Nov 2015 02:49:29 -0800
> Subject: [Amps] SPE 1.3K-FA and FTDX-5KMP
> Date: Sat, 14 Nov 2015 08:28:13 +1030
> From: "Leigh Turner" <>
> To: <>
> 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
> ### 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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