[Milsurplus] AN/MRR-2 receiver video - rare prototype

Fri Dec 30 10:57:52 EST 2016

RayIf you have any modules for the KWT-6 or ARC-58 family of radios that you will be passing on, give me a heads up.  Especially the Stabilized Master Oscillator (SMO) module and the Side Step Oscillator, both seem to have components that are more prone to catastrophic failure then any of the other modules.TIA,Jim

      From: Ray Fantini <RAFANTINI at salisbury.edu>
 To: Milsurplus List <Milsurplus at mailman.qth.net> 
 Sent: Friday, December 30, 2016 9:45 AM
 Subject: Re: [Milsurplus] AN/MRR-2 receiver video - rare prototype

#yiv3429642642 #yiv3429642642 --P{margin-top:0;margin-bottom:0;}#yiv3429642642 Have owned a couple SRR-13 receivers in the past, do not remember if they were “A” variant or not but do know they were not the RCA version, at least not the same as other RCA versions that I have seen. It’s a good radio, like using it and would use that before something like the larger, heavier R-390 family of radios. The frequency display and AGC action are far superior to the mechanical nightmare in the R-390 but the long term serviceability is a issue. Dam near impossible to work on the sub assemblies, find or replace the tubes although I do not recall ever seeing one fail and the issues with coils and filters has already been brought up. Its just a matter of opinion but with the ease of service, except mechanical alignment, parts availability and the high amount of radios on the market to provide a almost endless supply of parts will see the R-390 in use by Hams and collectors for decades but the SRR family sliding into obscurity. Not saying one is any better then the other and in my case have progressed beyond tube technology of the forties and fifties and prefer to spend my time on first and second generation solid state technology of the sixties and seventies. I find better performance and the added benefit of real SSB operation in the General Dynamics, Harris, Cubic, Watkins Johnson and Sunair equipment that replaced all the hollow state technology of the fifties and spend the majority of my time with that equipment. The only dealings that I have these days with the old vacuum tube stuff is collecting it up and selling at Ham fest. Note the reference to Frost fest where I will be selling a truck load of BC-348, ARB and other WW2 technology.
Ray F/KA3EKH 

From: Milsurplus <milsurplus-bounces at mailman.qth.net> on behalf of antqradio at sbcglobal.net <antqradio at sbcglobal.net>
Sent: Friday, December 30, 2016 1:48 AM
To: Milsurplus List
Subject: Re: [Milsurplus] AN/MRR-2 receiver video - rare prototype I looked through the Rovero document but didn't find anything on frequency drift.  Ken, can you be more specific on location?
The SRR-13A and FRR-23 that I have repaired do not seem to suffer from any significant drift.  Either one, once set to WWV at 10 mc, will come back up from a cold start on frequency as soon as the receiver is up and running; takes about two minutes.  They seem to stay on frequency for hours with no need to touch up the tuning dial.  Both radios are stock but I have changed the power transformer primary taps.  The 125 volt tap on one side of the primary and to the 400 cycle tap on the other which further lowers the filament voltage to about 5.9 to 6.0 volts and a correspondingly lower B+ voltage.  There are other minor fixes / preventive measures that I would be happy to share if there is any interest.
Ken is correct about the coils in SRR-13A receivers having issues resulting from corrosion.  I have had several RF coils / transformers that are open and found it easier to just replace rather then rewind.  There seems to be fewer variations in the RF coils / transformers then the part numbers suggest so I have been able to replace open units from other modules from scrapped receivers.  Those radios that were scraped had smoke damage and were missing some modules and dust covers.  All of the SRR-13A receivers, around 12, that I got came from an auction of the estate of James Blackmon, who was a medical doctor and avid radio collector here in Arkansas.
To be fair, several levers were found to be cracked where the lever connects to the module.  I attribute the lever issue to what was referred to as "brogan maintenance" in tech school.  It seems to be easier to torque the 4-40 screw then to lube the binding mechanics. This same issue is also found in the Collins R-390 Oldham couplers, for the same apparent reason.  
Ray, is your receiver an SRR-13 or SRR-13A?  I have several SRR-13A receivers and one FRR-23 but no SRR-13 examples.  I wonder if the frequency drift problem was addressed in the later SRR-13A?  The only difference that I have noticed about the SRR-13 as compared to the SRR-13A or FRR-23 HFO is that the later uses a triode oscillator while the SRR-13 used a pentode.  All other passive components seem to be identical in either HFO.
The SRR-13A has the same "cool factor" for me as the R-390A.  Neat mechanics, interesting frequency display and the heft factor of a cold war era military receiver. 
Funny, never had a bad RCA mechanical filter in an SRR-13A.  Wish I could say the same about the Collins R-390A!Jim
From: Kenneth G. Gordon <kgordon2006 at frontier.com>
To: Milsurplus List <Milsurplus at mailman.qth.net>
Sent: Thursday, December 29, 2016 1:24 PM
Subject: Re: [Milsurplus] AN/MRR-2 receiver video - rare prototype

On 29 Dec 2016 at 18:29, Ray Fantini wrote:

> Perhaps it´s was an opportunity to provide the USMC the same drift and snapping
> levers

Both of which were fixed later by RCA, and can now be fixed by users. See this:

http://www.roveroresearch.org/home/boatanchor-radios/srr13

and

http://www.roveroresearch.org/home/boatanchor-radios/srr13/srr-13a---switch-arms

> that the Navy valued? It looks as if it did not get far beyond the prototype 
> and field test though.

Apparently it went further than that, but there were very few made or implemented.

In addition to those pesky switch-arms, and the drift, another big issue with them is that the
RF and HFO coils often go bad: open or shorted. Despite being sealed, they get corrosion
in them.

These can also be fixed, although it is a big PITA. 

I have a Morris Coil-Winder that makes the job a bit easier...

The rather huge manual gives exact specifications on the coils.

Still, I have always liked the SRR-11/12/13 when they are working to specifications.

I understand that the Navy radio operators roundly hated them though...and I don't blame
them one bit. They must have been a maintenance night-mare in that service.

The later R-390/URR and even later yet R-390A/URR were far more reliable.

Ken W7EKB

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