[ARC5] [Milsurplus] Opinions on ARR-7

[J. Forster]

> Like the others, I couldn't find a notation for a PP-33 in any of my
> directories, nor ever saw one, John.

I wa given the number in an email. My bad for not checking the info before
using it. It really seemed logical.

> 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.

Exactly. I first saw the setup w/ the SPA-1 in the LIONFISH, but didn't
search out how it was powered.

> 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.

A power supply would be easier to build with today's parts. However, I'm
not sure I want to go there.

> 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.

Yes, that was essentially my intent.

Best,

-John

==================
>
> 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
>> ===============
>
>