[R-390] Yet another undocumented mod?

[Don Reaves]

Roger,

I thought I had heard all the anecdotes about R-390 early uses but this one
spawning a company like DEC is new to me.
Fascinating.  Do you have any citations that I can read up on that?

Don


On Tue, Jan 13, 2015 at 8:09 PM, Roger Ruszkowski <
flowertime01 at wmconnect.com> wrote:

>
> Fellows,
>
> Once upon a time there was a series of R390As that were modified to be
> what we would consider as scanners. It took six racks of stuff to make
> this so.
>
> This six rack critter launched a small company in Maynard Mass called the
> Digital Equipment Corporation.
>
> The out put was that every oscillator in the receiver was coupled out to a
> frequency counter.
>
> This IF deck may be from one of these receivers.
>
> Every thing was summed up or subtracted as need so the nixie tube readout
> gave a number that represented the frequency to which the receiver was
> tuned thus implying
> the signal of interest was also at that frequency.
>
> The BFO in the IF was easy. A longer cable was used from the IF deck
> connector
> to another BNC connector next to the 455 KHz back panel connector.
> The original 455KHz output was coupled into an different FM and AM
> detector.
> These dual detectors were used to find the zero center of the incoming RF
> signal.
> The audio outputs were the stock R390A audio and were patched to an
> operator with split head sets.
>
> The VFO, first, and second mixers were  more complex operations.
>
> Some one would read the nixie numbers out loud across the bay.
> The designated operator would spin his receiver over to the frequency and
> use the
> audio patched to his position to find the signal.
> As soon as the signal was being tracked by an operator the scanner was set
> free to find the next signal.
>
> The guys use to set the scanner to watch a frequency range where a net was
> expected to
> come up soon. As soon as some one started to transmit in the range and the
> scanner caught it
> a half dozen ops would spring over to do intercept.
>
> There were methods to the intercept operators behavior.
>
>
> Roger AI4NI
>
>
>
>
> -----Original Message-----
> From: Dennis Wade <sacramento.cyclist at gmail.com>
> To: Larry Snyder <larrys at teamlarry.com>
> Cc: R-390 HF Receiver List <r-390 at mailman.qth.net>
> Sent: Tue, Jan 13, 2015 8:15 pm
> Subject: Re: [R-390] Yet another undocumented mod?
>
>
> Possibly to inject a crystal controlled BFO for USB/LSB?  Just a thought...
>
>         Dennis
>
> On Tue, Jan 13, 2015 at 3:27 PM, Larry Snyder <larrys at teamlarry.com>
> wrote:
>
> > Hi folks --
> > The more I look at the stranger it gets.  My IF deck has an
> > unlabelled mini-BNC connected through a 270 pF to the BFO plate.
> > Anyone know why this may have been added?
> >
> > thanx,
> > -ls-
> >
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>
>
> --
> "If they trust you, it is an extraordinary privilege, and you simply can't
> abuse it."
>       - A. Alan Post  1914-2011.  California Legislative Analyst 1949-1977.
>
> -------------------------
> Dennis L. Wade
> KG6ZI
> Carmichael, CA
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-- 

Don Reaves  W5OR WD2XSH/15
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