[Milsurplus] SRR-13 Article, more

Mon Aug 1 01:58:15 EDT 2016

I am still puzzled by the Hutchins articles.  Yes, the Radionerds article seems incomplete so I look forward to the last few pages.
A few weeks ago I got the FRR-23 up and running and a week later the first of a possible of four SRR-13A's.  I honestly do not see the issue of the first oscillator tracking as reported by Hutchins.  To the contrary, tracking appears no better or worse then any other receiver of that era, including the R-390A.  To put it another way, once the RF modules are calibrated and the Calibrator is put on frequency, one can dial in a cal point, set the dial and then go to the desired frequency and then be on frequency.
Walt also reported that the crystal calibrator has too high an output.  This is true for the lower bands but the calibrator runs out of gas on the top band.  Going from AGC to Manual Gain and reducing the receiver gain does make dial calibrating on the lower bands a trivial task.
As to the issue of distortion, once all of the molded paper capacitors were replaced in the 2nd IF and Audio tube assemblies, all is just fine, as is the AGC system.  I am beginning to think that many of Walt's issues are the result of leaky molded paper capacitors.  Every molded paper capacitor that I have examined have anything from hard to see fine to obvious major cracking in the plastic coating.  The few glass sealed metal body paper capacitors that I have tested for leakage appear to be just fine.  So far, I have found a few weak tubes in the first SRR-13A, one in the Antenna Module and another was the 5902 audio power amplifier which Walt also had an issue with.
Once aligned, the SRR-13A beats the published specs of 5 or so microvolts for 10 dB signal plus noise over background noise.  Minimum detectable signal is at about one microvolt or less.  I will know more once the second SRR-13A is reworked.
Walt did not give a serial number or contract date on his receivers so I have no idea how early or late his receivers are in the great scheme of things.  The FRR-23 is later production then the SRR-13 and all of my SRR-13A's are late production and made by Magnavox. IIRC.  For all practical purposes, the FRR-23 and the SRR-13A are the same receiver except possibly for the dual diversity option that is built into the FRR-23 but I am not sure that this is included in the SRR-13A.  There might be additional differences like remote First Oscillator and remote AGC but for single receiver operation, both models seem identical.
All of the SRR-13 2nd IF modules that I have, except for one, were built with mechanical filters instead of L/C.  Two of the power supply modules are original so the 6X4's and ballast tube are still in place.  In a week or so, I should have the second SRR-13A up and running.  Two more are possible but these will be missing the top covers for the 2nd IF and Audio modules.  I have more modules then receivers since I have scraped several receivers that had fire damage but the modules seem to be in good physical condition.
I will know more on the average receiver performance once the second SRR-13A is up and running.  If anyone has technical manual updates for the SRR-13A, I would apprecate a heads up.Jim

      From: Hubert Miller <kargo_cult at msn.com>
 To: milsurplus at mailman.qth.net; armyradios at yahoogroups.com 
 Sent: Sunday, July 31, 2016 11:11 PM
 Subject: [Milsurplus] SRR-13 Article, more

Boys and girls, re the AN/SRR-13 Hutchins article which Chris Story posted on his splendid Radionerds site.I was sorting and packing up books and documents today, and i seem to have found more pages on thisreceiver. Three more pages, meaning 6 pages of text, with one table and a couple schematics. I just lookedat Radionerds to try to identify whether what i came up with before already includes this material, and i didn’t see the schematics, which seem do deal with AGC and a voltage regulator. I am going to mail theseto Chris this week, so depending on his schedule, you may have the interesting ‘rest of the story’ availableto you online, or at least, more of the story. The topics covered in the additional material are AGC improvement; regulated HV; paint; something on crank arms; and additional stability note. Hope this helps out you SRR-13 enthusiasts out there.-Hue 
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