[Milsurplus] Question about EMP

[D C *Mac* Macdonald]

I can tell you for sure, that the FRC-93 (KWM-2A) gear
that I last worked on in 1981 was certainly reaching the
end of its useful life.  I certainly would not have wanted
to own any of those and many of them were better than
those being used in mobile units such as 3d Combat Comm
Group at Tinker AFB here in Oklahoma City.

When you consider that was 25+ years ago, I seriously
doubt if any great quantity of "primo" items remained.

IIRC, the KWM-2s were subject to front end tuned circuit
burnout in the preselector from close, strong, in-band sigs.

Rigs which used the transmitter output pi-network as the
first RF circuitry in the receive mode were pretty much
immune to that sort of thing.  I knew of Drake/Swan/
National users who delighted in tuning up near the KWM
stuff to smoke the front ends!!

Mac - K2GKK/5
Oklahoma City



----Original Message Follows----
From: <scottjohnson1 at cox.net>
To: "Todd, KA1KAQ" <ka1kaq at gmail.com>, whitaker at ieee.org
CC: Military Surplus List <milsurplus at mailman.qth.net>
Subject: Re: [Milsurplus] Question about EMP
Date: Mon, 27 Nov 2006 7:57:09 -0800

I respectfully think this is all BS, Mac had a small lot of the cabinets 
custom made by the original mfr. Also, The B-52 which, is probably the most 
EMP protected asset going, has plenty of gear with SS front ends.  High Mu 
Frame grid front end tubes are also very static sensitive, probably more so 
that a protected FET.   This fanciful notion that the Russians held on to 
tubes for EMP reasons is pure hogwash, they simply didn't have the 
technology at hand to produce good low noise devices.  They lagged the west 
by 8-10 years in semiconductor technology, and when they could design in 
western parts, they certainly did so.   I can relate to you first hand there 
is no old equipment "Stashed" in Cheyenne Mountain, there is no room for it. 
  EMP protection is just as important for tube and hybrid gear as for MOS 
populated gear.  I think one advantage radios like the R-390A have over 
typical solid state designs is much better IM performance in a strong signal 
environment, such as a naval vessel, or a comm central.  The fact that the 
GRC-106 and R-1051 were designed to run in a full duplex environment may 
account for the continued use of front end tubes as much as anything else.

Scott