[Milsurplus] HRO RAS AVC Issues

[Jim Whartenby]

There is a similar problem with the KWT-6 / URC-32 SMO.  The Interpolation Oscillator absorbs moisture and causes oscillator instability.  Cure is to put the SMO in an oven at about 220 deg F for a couple of hours.  Be sure to have the Oldham coupler facing up so that the wax in the IO will reflow down and re-seal the ferrite slugs.  I wrap the SMO in an old towel to keep the oven crud off of the SMO.  I would assume the same process will drive the moisture out of the RAS / HRO.Jim

Too much agreement kills a chat.  E. Cleaver

-----Original Message-----
From: David Stinson <arc5 at ix.netcom.com>
To: Ray Fantini <RAFANTINI at salisbury.edu>; milsurplus at mailman.qth.net <milsurplus at mailman.qth.net>
Sent: Mon, Aug 9, 2021 9:51 am
Subject: Re: [Milsurplus] HRO RAS AVC Issues

 Isn't there an issue with National receivers, where the 
 phenolic on the coil contact board absorbs moisture over
 the years and becomes "leaky" for AVC voltage?
 I had an NC-100 do that once.  It was the AVC feed to
 the RF amp IIRC, and I ended-up just disconnecting
 the AVC line at that point from the terminal board.
 AVC worked acceptably that way.
 Anyone remember details?
 Dave S.
  On 8/9/2021 9:05 AM, Ray Fantini wrote:
  
 
 _filtered {} _filtered {}#yiv9944569072 p.yiv9944569072MsoNormal, #yiv9944569072 li.yiv9944569072MsoNormal, #yiv9944569072 div.yiv9944569072MsoNormal {margin:0in;margin-bottom:.0001pt;font-size:11.0pt;font-family:sans-serif;}#yiv9944569072 a:link, #yiv9944569072 span.yiv9944569072MsoHyperlink {color:#0563C1;text-decoration:underline;}#yiv9944569072 a:visited, #yiv9944569072 span.yiv9944569072MsoHyperlinkFollowed {color:#954F72;text-decoration:underline;}#yiv9944569072 span.yiv9944569072EmailStyle17 {font-family:sans-serif;color:windowtext;}#yiv9944569072 .yiv9944569072MsoChpDefault {font-family:sans-serif;}#yiv9944569072 div.yiv9944569072WordSection1 {} Noticed that my HRO RAS was starting to be less sensitive then some of the other radios around the shop so decided that I would pull it apart and see what’s going on. This is the first time in about ten years that I have had the covers off. The Navy RAS is a copy of the National HRO jr receiver with several changes that include having a lower IF frequency of 175 kHz and a 6V6 audio output tube unlike the civilian version.  
 


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