[Premium-Rx] Fwd: Applied Communictions SR-2174

[Terry O']

Can anyone on this list help this guy out?  I have nothing on the 
Applied Communications SR-2174.

Please keep me in the loop as I'd also like to know about this radio.

Terry O'



-------- Forwarded Message --------
Subject: 	Applied Communictions SR-2174
Date: 	Mon, 31 Dec 2018 12:30:22 +0000
From: 	Bekir Ayman <bayman66 at hotmail.com>
To: 	watkins-johnson at terryo.org <watkins-johnson at terryo.org>



Hi Terry,

I am an engineer who worked for the, now defunct, GEC Marconi 
Communications Ltd. in the 90s and was involved in the manufacturing and 
R&D efforts on "Black Radios" namely, HF equipment with frequency 
hopping, COMSEC, ALE etc. capabilities.

Apart from that I am interested in collecting military comms. equipment 
of the 60s and further on. Over the years I have acquired and sold 
several aircraft radios even dating back to F-84, F-86 era, the usual 
R-390, some W-J radios, several HP signal generators etc.. I am not a 
licensed amateur but, as a hobby, I am on the side of construction of 
amateur equipment as well as renovating military radios. In that respect 
I make use of your site in identifying equipment.

Recently, I came accross an SR-2174 from Applied Communications, which I 
understand, is the descendant of Astro Communications Labs and Norlin 
Communications. Unfrortunately there is no more info, neither on your 
site nor anywhere else on the web as to what its products were and any 
related manuals/documentation.

I wonder if you have any information on this model since it get the 
impression from a quick examination that it was quite a hi-tech piece of 
its time. It is a blade,  implying several units operating together 
under central control. I enclose photographs of front and rear panels 
for info. Initial examination of the radio hinted me the following;

  * Several SR-2174s were controlled by a central computer since it does
    not have any tuning facilities or displays on the unit.
    Additionally, a GPIB (or something similar) connector as well as an
    RS-232 connector exist on the rear panel. The only output is the
    audio with volume control, which was probably used for manual
    monitoring of communications through that specific unit.
  * It is a VHF/UHF device with a 500MHz LPF at the RF input, most
    likely covering 20 - 500MHz band.
  * First IF is 681.4MHz provided by a custom design K&L bandpass
    filter. Second IF is 21.4MHz through a crystal filter. Probably a
    third IF stage is following at 455kHz (I have not examined in detail
    yet).
  * 1st and 2nd LOs are PLL controlled by the then state of the art
    MC14515X series PLL synthesizers from Motorola.
  * It is microprocessor controlled, using NSC800 of National Semiconductor.
  * An interesting point is that the first and second mixers look like
    custom made components, perhaps for improved dynamic range and
    itermodulation characteristics.

I would be grateful if you can provide, or hint where I can obtain any 
info regarding this unit. If interested I can provide you with more data 
as I examine the unit in more detail.

Thanks in advance for your help and wish a merry Christmas and a happy 
new year.

Bekir Ayman