[Milsurplus] [ARC5] Opinions on ARR-7

[Mike Hanz]

Like the others, I couldn't find a notation for a PP-33 in any of my 
directories, nor ever saw one, John.  Doesn't mean it doesn't exist - it 
would have been useful for a shipboard application in a small ship like 
a submarine, I suppose.  I'm using a PP-32/AR with my AN/ARR-7, but it 
does require a 400Hz supply, and I have been thinking about a small 
series B+ regulator for the cable between the two boxes because it 
retained the 270-280vdc B+ that the original SX-28 used for most of that 
set.  It just makes everything run hot inside to no real advantage since 
you don't need any audio power to speak of.  I've tried running it at 
the 166v that the RAX used with a similar receiver design and it does 
make things run quite a bit cooler without any apparent performance 
compromise.

Frankly, I prefer the ARR-7 to the BC-348, partially because of the 
flexibility of the IF selectivity settings.  Having said that, it 
doesn't have the nice feel of an SX-28A in tuning around the bands, 
though it does have about the same electrical performance (duh).  Back 
when I researched it years ago, it appeared that the ARR-7 was designed 
in 1942, most of the work being to repackage the SX-28 and remove the 
heavy parts not needed for a surveillance set, but there were a few 
small RF and IF circuit changes that eventually found their way into the 
slightly later SX-28A.  The motor drive mechanism for it and the 
AN/ARR-5 (repackaged S-27/S-36 VHF set) was reportedly quite fragile and 
had a rather short lifetime, so I don't use the ones in mine except for 
an occasional demonstration of how they work, even though I've relubed 
them with synthetic grease to reduce friction.  I did make one small 
modification to it - jumpered plate and grid of the anti-radiation 
isolation stage with a small mica capacitor soldered to a couple of tube 
pins inserted into the tube socket. The original design simply added a 
bunch of noise to the receiver without any useful purpose.  I made the 
same change to the ARR-5 input stage.  Pairing with an AN/APA-10 
panadapter and an APA-6 or -11 pulse analyzer is an interesting thing to 
do if you have the space and power.  I normally use it with an 
interphone amplifier to get the power for a speaker - the LS-184/AIC-10 
- but any outboard amp can of course be used.

73,
Mike  KC4TOS

On 8/26/2012 10:42 PM, J. Forster wrote:
> >From N7JR:
>
> Power Supply, PP-32/AR
> JAN Type: PP-32/AR
> Nomenclature: Power Supply
> Reference: AN 08-30ARR7-2
> Weight: 25
> Part of: ARR-7
> Description: The PP-32 provides all the power necessary to power three
> receivers, R-45, in radio receiving set ARR-7.
> Source: AN 08-30ARR7-2
> Created: Wed Jul 12 19:24:04 2000
> Last Modified: Wed Jul 12 19:24:04 2000
>
> -John
> ===============