[R-390] General history on our website also updated

[Jim Whartenby]

Larry
 It seems to me that, in general, history is full of nooks and crannies that are difficult to explore so are often just glazed over to get to the subject at hand.  That the R-390 followed the development of the 51J is somewhat obvious to the casual observer but this raises the question as to the origins of the 51J.

The Collins radios that predate the 51J and have most of the same key components of the 51J are the ARC-2 and ARR-15.  Both contain the first Collins permeability tuned oscillators and use a variable permeability tuned RF amplifier slug rack.  The ARR-15 adds a variable permeability tuned IF amplifier slug rack and a unique method used to tune the radio to frequency.  As I see it, everything is there in the ARR-15 with the exception that the receiver is of single conversion design.

If one accepts that there is no spontaneous generation, that is to say that nothing appears out of thin air, then there is a back story to explore for both of these radios.  The Naval Research Laboratory must have had a hand in the development of both the ARR-2 and the ARR-15 since both have used the new approaches to radio design and both were used only in Navy aircraft.

The 51J must have a similar story of development that goes back to at least WW2 but now the Signal Corps is the behind the scenes prime mover.  There might be some evidence of this if the original RFQ (Request For Quote) and other correspondence can be located in the archives of either the Signal Corps or Collins Radio.

Regards,

Jim


Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy

-----Original Message-----
From: Larry H <larry41gm at gmail.com>
To: R-390 Forum <r-390 at mailman.qth.net>
Sent: Sun, Feb 27, 2022 2:24 am
Subject: [R-390] General history on our website also updated

I found a website that has a very nice write up about the history of the
R-390 and R-390A by *Luca Fusari*
<http://lucafusari.altervista.org/page9/AmericanRadio.html>.  There's a
link to it in the first entry of our 'history' section on our website,
r-390a.net.  Let me know what you think.

Regards, Larry
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