[Milsurplus] OA-65AMRC-2 Receiver

[Joe Connor]

I found a manual for the OA-65/MRC-2:
 http://www.pestingers.net/PDFs/Other_radios/Military_manuals/TM%2011-850%20C1%202%20Jun%2052%20NJ7P%20AS.pdf
 
It explains the changes etc. 
 
I'm plugging away on mine. I've gotten the leaky old Micramolds out of the RF oscillator, IF cans and 1st detector can. I dropped the 1st RF box today and changed the two leaky caps inside. Slowly but surely, this set is turning into a nice receiver. In the next day or two, I'll do the 2nd RF and Detector boxes. As of now, this receiver is pretty sensitive and has good audio. 
 
I have a lot of cosmetic work left. While the exterior is fairly nice, the interior is a mess. It has a surprising amount of rust and corrosion for a set that was MFP'd. For some unknown reason, this set is missing a lot of screws. There aren't many signs of repair work so I'm puzzled as to why so many screws are gone. Oh, well, missing screws are why God invented hardware stores.
 
I found a couple of interesting things:
 
    1. Sheet styrene is great for making a replacement dial cover. I used Evergreen Scale Models Item No. 9006 (.010" thick). It cuts easily and looks good. It's available at most hobby shops.
 
    2. The power supply spacers were missing. A wooden dowel makes a nice emergency replacement and keeps the top of the power supply from touching components on the underside of the chassis. I'll paint this dowel and leave it in place until I can find a real spacer. 
 
 
                                    Joe Connor


>________________________________
>From: "WA5CAB at cs.com" <WA5CAB at cs.com>
>To: kargo_cult at msn.com; milsurplus at mailman.qth.net 
>Sent: Tuesday, May 29, 2012 9:58 PM
>Subject: Re: [Milsurplus] OA-65AMRC-2 Receiver
>
>Hue,
>
>First, the receivers modified to OA-65/MRC-2 weren't BC-312's, they were 
>BC-342's.  I know that there are only relatively minor differences, but if you 
>find either receiver unmodified other than the removal of either the DM-21 
>or the RA-20, identifying which you have is trivial.
>
>Second, I think the other receiver you are referring to is R-336/GRC-26, 
>not R-339.  I've been unable to turn up any evidence for the existance of an 
>R-339.  R-336 was a modified BC-342-N.  The major modifications consisted of 
>component value and type changes in the HFO stage, including changing the 
>tube to a 6J5, and in the mixer stage.  Other changes were the addition of an 
>IF output from the cathode of the 2nd IF amp terminating in an SO-239 on the 
>front panel, changing the antenna connector to an SO-239, and replacing the 
>RA-20 with an RA-20-B.  All of these changes are the same as were 
>accomplished in Receiver A of OA-65/MRC-2, except that in the latter, the HFO signal 
>was also run to a connector added on the rear of the receiver.
>
>Robert D
>
>In a message dated 05/29/2012 15:33:43 PM Central Daylight Time, 
>kargo_cult at msn.com writes: 
>> Somehow I got the idea that G&G was importing BC-312 series MRC-2 
>> receivers from France around early 1970s. I'm reasonably sure I got this
>> info straight from them, either by letter or by phone call around 1972.
>> But - I have never ever seen such a modified receiver, altho I have 2
>> SARF French BC-312s.  I wonder how they got over here. You'd think
>> the supply of BC-312s here would be enuff to satisfy war-surplus era
>> demand, but maybe G&G got a good enuff deal to import all varieties
>> of BC-312. 
>> Now what about the R-339 ( KW BC-312 ), what's the story on that?
>> Are those gov't rebuilds, and why the new nomenclature? I have only
>> seen one of those here. Still think time to time, I should buy it, but
>> have maybe enough of these heavy beasts already, plus a recent 
>> surgery is making me take a less cheery view of the heaviest metal.
>> -Hue 
>> _______
>
>Robert Downs - Houston
>wa5cab dot com (Web Store)
>MVPA 9480
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