[Milsurplus] ARC-58 development report

[antqradio at sbcglobal.net]

Thanks Nick!Interesting to note the problems that are reviled when equipment leaves the laboratory and is operated in field like conditions.
I was surprised that the problem with the Sidestep Oscillator's mechanical filter (page 30) was known this early but still remained an issue throughout the life of the ARC-58.  Of the many mechanical filters in this transceiver (and the various clones like the KWT-6 and URC-32) this 200 cycle nose mechanical filter seems to me to have the highest failure rate.  Other Collins mechanical filters seem to suffer from the internal support rubber turning into a goo which then increased filter insertion loss or sometimes breaks the fine wires to the input/output transducers.  The Sidestep Oscillator mechanical filter always seems to fail catastrophically.  One can actually hear the disks in a failed filter rattling inside the housing when it is gently shook.
This report also mentions (page 24) the Interpolation Oscillator's problem with moisture changing the IO's frequency and preventing frequency lock of the SMO.  This finally explains the problem that NA4VY had with his URC-32 which is operated in his basement shack.  When tested here the SMO was OK and locked up on frequency every time, when operated in Dave's basement, it would loose frequency lock.  Tried several times to reflow the wax covering the IO to keep the moisture out but was never successful; very frustrating!Regards,Jim

      From: Nick England <navy.radio at gmail.com>
 To: Military Surplus Mail List <milsurplus at mailman.qth.net> 
 Sent: Sunday, January 22, 2017 1:16 PM
 Subject: [Milsurplus] ARC-58 development report
   
FWIW
https://www.cia.gov/library/readingroom/document/cia-rdp81-01043r002500180007-4


Nick
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