[R-390] Yet another undocumented mod?

[David Wise]

It sounds like this is not the same as the R-1240.  Do you remember if it got a real model number, or was it just a mod?

Dave Wise

________________________________________
From: R-390 [r-390-bounces at mailman.qth.net] On Behalf Of Roger Ruszkowski [flowertime01 at wmconnect.com]
Sent: Tuesday, January 13, 2015 6:09 PM
To: r-390 at mailman.qth.net
Subject: Re: [R-390] Yet another undocumented mod?

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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