[Elecraft] Collins and Mechanical Filters (was at one time about up-conversion)

[Fred Jensen]

How these threads do morph!  I don't know about RCA MF's, but I can 
attest to the extreme non-fragility of the Collins variety (and in fact 
"everything Collins").

In the mid-60's, while in the USAF (1Lt), I commanded an airborne team 
whose missions were to put mobile, hardened TACANS on various mountain 
tops in undisclosed locations for 10-15 days.  After getting down, we 
got our equipment out of the C-130 using LAPES (Low Altitude Parachute 
Extraction System).  The gear was mounted on shock pallets, the A/C made 
a low pass and, with a tail-hook apparatus, snagged a shock cable we had 
erected on flimsy poles, and flew out from under the pallets.  Snap 
opening cargo chutes "landed the pallets," as the system description 
quaintly said.  Despite all the shock protection, "landed" was really 
stretching the term, even for the guvmint.

The pallets always contained two KWM-2A's packed in aluminum foam-lined 
cases which we used to communicate with our FOHQ south of the 17th who 
coordinated the CH-3's to come pick us up when we'd run out of JP4 for 
the generators.  The tubes were packed separately, but other than that, 
the 2A's were stock, ready to transmit.  We did 24 of these missions and 
I lost four troops, but we lost zero out of 48 -2A's.  Collins also 
manufactured our A/G radios (can't remember their nomenclature at the 
moment), and we never lost one of those either.

Unfortunately, our missions ended by lighting off thermite on the pile 
of equipment ... burning up 48 perfectly serviceable, beautiful KWM-2A's 
was really really hard for a ham, and I wondered if my ham colleagues 
would ever forgive me.

I used an S3-line for years, and while I don't have it any more to do an 
A/B test, based on my memory (a bit leaky these days), I think the K2 IF 
filters will easily stand up to the mech filters ... and, unlike the 
MF's, I can tailor the K2 filters as I wish.

I think someone suggested that the move from AM to SSB was driven by the 
superior filtering that became available at the same time (please 
forgive me if I got that wrong).  Personally, I think it was VOX.

Re R390A's:  The Wullenweber array and station at Clark AB in the 
Philippines, operated by the ATDE ("Agency That Doesn't Exist"), used 
390A's.  I wasn't permitted to know for what.

Fred K6DGW
Auburn CA CM98lw