[Milsurplus] AN/APR-4Y

[Mike Hanz]

On 5/29/2013 4:55 PM, Ray Fantini wrote:
> Have been wasting tons of time on primitive counter measure receivers that I bought at Dayton...

Nothing of the sort.  Time spent is well spent. :-)

> (1) what is the B+ voltage that was provided to the tuning heads? Think it may be +300 but not certain.

It is indeed.

> (2) What was the rated sensitivity for the APR-4 in AM narrow and wide? And what was it for the 4Y in AM narrow, wide and FM?

T.O. 12P3-2ALR-5-2 (which is the set of which the APR-4Y is a part) sez:

                     IF atten Sensitivity in uV
                  sw setting                  Wide Band Narrow Band
Band A           12 10-20                         5-20

Band B             6                              10-20 5-20

Band C             0 15-30                       10-30

Band D             0 15-70                       10-60

Selectivity in MHz:  Wide Band  4.0 +/- .4MHz   Narrow Band  .45 +/- .15MHz

Note that the IF attenuation switch has quite a bit of padding switched 
in at the lower frequencies, probably because of noise.

I didn't have time to look at the APR-4 manual, but it will have higher 
figures because of the different front end tuning units used.  The 
CV-253 is more sensitive because it uses miniature tubes instead of a 
simple crystal or thermionic diode mixer.

> (3) Is the CV253/ALR multiband head the only correct head for the 4Y?

It's the only one shown in the ALR-5, but the older units all work, 
IIRC.  I have a spare T.O. I can send you if you like.

> (4) I now realize that the APA-10 Panadaptor appears to be a correct display for that receiver. Saw two at Dayton including one in good condition but did not buy it and am now regretting it.

It is certainly "a" correct display, in that it displays an IF of 30MHz, 
but it was superseded by the APA-38 and later units that didn't require 
a manual sweep of the sweep knob to get a display.

73,
  -Mike  KC4TOS