[ARC5] interesting ?

[jeepp]

I think it was the APR-4Y that included the 60 Hz capability.K3HVG


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-------- Original message --------
From: Tim <timsamm at gmail.com> 
Date: 2/23/18  23:10  (GMT-05:00) 
To: Michael Hanz <aaf-radio-1 at aafradio.org> 
Cc: ARC-5 List <arc5 at mailman.qth.net>, Roy Morgan <k1lky68 at gmail.com> 
Subject: Re: [ARC5] interesting ? 

Hi Mike - Interesting stuff....I have an APR-4 with several tuning units.  It operates on either 115V 400 or 60 cps AC power (plus 28VDC for the motor I think) , 60 cps is something I always wondered about.  For an airborne set anyway.  
Perhaps that was a holdover from the GR Lab instrument design?  Or maybe for shipboard ESM work?

Tim
N6CC

On Fri, Feb 23, 2018 at 7:51 PM, Michael Hanz <aaf-radio-1 at aafradio.org> wrote:

  
    
  
  
    On 2/23/2018 4:28 PM, Roy Morgan wrote:

    
      Am I right in assuming that these things (the Ebay frequency converters)
        preceded the APR-4 and APR-4Y?

      
    
    

    Slightly (mid 1943 versus early 1944), but
      definitely not the APR-4 predecessors mentioned below, which were
      all derived from the General Radio P-540 microwave receiver.

    

    
      
         THE APR-4's were in use in the 50's into the 60's I would
          guess.
        I have where I am an APR-4Y (which runs on 400 - 800
          cycles) but I think no plug-ins.

          Elsewhere I do have some plug-ins for this thing.  I may have
          to lash up a big audio amplifier to run it.
      
    
    

    If you have a hefty 28v power supply, you
      might look for 400~ aircraft inverters.  Occasionally you will
      find one for a reasonable price.  The APR-4 takes about 110 watts
      of 400~ power.  I have found them at hamfests for $5 to $10.

    

    
      
        These things are interesting to me because they originated
          from a General Radio device meant to be used with slotted
          lines and the like that produced an "IF" frequency of 30 mc. 
          It *may* have been an MIT Rad Lab project to upgrade the GR
          thing.
      
    
    

    Yes to both subjects you raised.  Dr. Alfred
      Price, for his Doctoral Thesis in 1985, documented an interview he
      had with Dr. Don Sinclair:

    

    "At about this time [circa late 1940]
    Dr. Don Sinclair, a Canadian working with

    the General Radio Company at Cambridge, Massachusetts, began

    work on the receiver portion cf a field strength measuring set

    intended to cover the band 100 to 3,000 MHz. To achieve the required

    broad tuning range, the receiver used the novel ' butterfly' tuning

    device which Sinclair himself had invented. It soon became clear
    that

    the unusual receiver might be suitable for a role quite different
    from

    that for which it had originally been intended, however, and in July

    1941 the Radiation Laboratory placed an order with General Radio

    for prototypes of an intercept equipment based on Sinclair's

    receiver. The device, which received the General Radio prototype

    designation P-540, was to become the first purpose-built US radar

    intercept receiver. During tests the P-540 continued to show promise

    and the Army Signal Corps placed an order for a hundred receivers

    of this type, now designated the SCR-587, with the Philco
    Corporation."

    

    The SCR-587 was also nomenclatured by the Navy
      as the "ARC" (think ARA, ARB, ARD...etc.), and then quickly, the
      "ARC-1", with some minor (Navy) improvements.  By then, we were
      into 1943 and it was obvious that the 587 and ARC-1 needed
      improvement, especially in the tuning area, which did not
      have single knob tuning.  It was like tuning an early superhet
      receiver, with separate oscillator and RF amplifier dials.  The
      APR-1 and APR-4 were the result of that need, but I would not call
      the APR-4 an upgrade from the APR-1 - full scale production came
      about the same time in early 1944 for both - the APR-1 driven by
      Navy requirements, and the APR-4 driven by USAAF specifications. 
      There were some IF step attenuation capabilities on the APR-4 that
      proved useful in the long run, so the APR-1 became another piece
      of flotsam in the sea of countermeasures receivers that became
      obsolete.  The APR-4 was re-nomenclatured again in the AN/ALR-5,
      this time with the CV-253/ALR tuning head, which covered
      38-1000MHz in four bands and greatly improved sensitivity, and the 400Hz powered
        APR-4Y being the only changes,.  The other two APR-4
      tuning units that covered up to 4GHz still worked in the
      mainframe.

      

      What is lost in all this summary was the fever of research and
      rapid improvements in the hardware, pretty much on a monthly
      basis.  Talk about a release version documentation nightmare!

      

                73,

       - Mike  KC4TOS

      

    

    

  


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