[Hallicrafters] R-45/ARR-7 Questions

[Carl]

Ive never worked on one Joe so the only comment I have is that those caps 
are most likely paper and even if mica long past their expiration date. The 
usual 400 or 630V .01uF axial lead cap is a fine substitute....but a disc 
cap is better for the RF section.
It would be interesting to find out how well the mil spec resistors have 
held up; Ive had to replace very few in other sets and often none.

Carl
KM1H


----- Original Message ----- 
From: "Joe Connor" <joeconnor53 at yahoo.com>
To: <hallicrafters at mailman.qth.net>; <milsurplus at mailman.qth.net>
Sent: Saturday, March 24, 2012 10:08 PM
Subject: [Hallicrafters] R-45/ARR-7 Questions


I just picked up a pretty nice R-45/ARR-7 (the airborne SX-28). It came with 
the PP-32 power supply. Thankfully, a prior owner replaced the power xformer 
so the set can operate on 60 cycle power. With a little tinkering, the set 
now works pretty well.

I have some questions that I hope you can answer:

1. From what I've read, it's a good idea to bypass V-12 (6AB7), the 
radiation suppression tube. How do I go about bypassing it?

2. Interestingly, most of the bypass caps are .0082 mfd, not .01 mfd. Are 
these mica caps or paper caps? If they're mica, I'll probably leave them 
alone.

3. The audio output (6V6) and 1st audio (6SQ7) each have a 20 mfd bypass 
cap. I'll be damned if I can find them. Does anyone know where they are 
located.

4. I know this is probably a needle in the haystack, but might anyone have a 
front-panel cover for the scanning mechanism?

5. Is there anything else that I should watch out for?

With this set, I got some paperwork that shows how good we have it today 
with the Internet. The fellow who owned this set in the '60s apparently 
tried desperately to find a manual for it. I have the letters that 
Hallicrafters and the ARRL wrote to him politely stating that they couldn't 
help. Now, we click on Bama and there's a manual on our computer screen. 
It's pretty amazing, when you step back and think about it.

As always, thank you for your help.

Joe Connor
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