[R-390] I got my R-390/URR

[Paul H. Anderson]

Jim,

On Sun, 9 Sep 2007, Jim Green wrote:

> OK,
>
> I finally got my R-390/URR. I put it on the bench and follows is a list of 
> the problems I discovered:
>
> 2)    The Mc tuning knob:
> 3)    The kc tuning knob:
>
> The kc tuning knob is a complete un-original replacement.

Dan Arney should have new ones.

> 4)    The bandwidth switch:
>
> The band width switch seems to function ok, but there is a very narrow step 
> between 8 and 16. All the other clicks are evenly spaced.

This sounds like a mechanical problem - you can pull the IF deck and make 
sure things are ok under there.  The most likely problem is just 
mechanical limits of the switch.

Is it going to .1KC ok?

> 5)    The Power Supply:
>
> V801 and V802 (both 26Z5W tubes) are missing. There are 2 each 100 ohm 
> resistors wired in series with the leads passing through the center hole of 
> the tube sockets. I haven?t taken a close look, but I suspect a previous 
> owner replaced V801 and V802 with solid-state diodes and replaced the ballast 
> tubes with the two 100 ohm resistors. I?m not a complete tube purist so the 
> solid-state diodes don?t bother me all that much. However, I don?t like the 
> idea of the resistors replacing the ballast tubes. I think I will undo that 
> mod.

This is probably an acceptable mod - some people put dropping resistors in 
to drop B+ just a little bit, because the 26Z5W tubes drop more than a 
pair of diodes do.  You just want to make sure it's safe electrically and 
thermally speaking.  If it appears safe, I'd just use it the way it is for 
awhile.

>
> 6)    The manufacturers tag:
>
> The tag is missing. I don?t know why people felt the need to remove these, 
> but there it isn?t. There enough parts inside that say Collins on them that I 
> suspect this one was manufactured by Collins not Motorolla.

Dan Arney makes these, also.


> 7) the green gear is missing.

Dan Arney makes these... you don't really need them that badly if you're 
comfortable with aligning the RF deck (it isn't that hard once you "get" 
what they're trying to do).

> Cosmetically the receiver is quite good. It?s clean inside and the tuning 
> dials turn freely. The best thing about it is it came in a genuine shock 
> mounted cabnet. On the whole I think it?s worth fixing. I have a few 
> questions:

You've got an amazing radio - you've got a keeper with a few costmetic and 
electrical issues!
>
> 1)    How does one go about removing the crystal oscillator sub-chassis? I 
> need to do this to check out the crystals.

Getting to the crystals is a pain - I think you need to pull the RF deck, 
then the crystal deck, then remove the insulated, heated cover which I 
recall was annoying.

> 2)    Where can I get the following parts:
>
> 2a: The green gear
>
> 2b: replacement tuning knobs
>
> 2c: a replacement manufacturers tag

Dan Arney makes all of these, plus locking pins for the R-391.

> 3)    Does anyone know what could be going on with the function switch? 
> And/or the AGC?

You can drop the panel, pull the switch, pry it apart and gently burnish 
the contacts, I believe, and it should/may work for many more years.

New switches are occassionally (rarely) available.  Better just to dig in 
and fix what you've got.

Failing that, just put the radion on a switchable power strip.

> 4)    Is the small step between the 8 and 16 position on the bandwidth switch 
> normal? Can it be adjusted or repaired?

It doesn't sound normal, but I don't have one in front of me.  I'm sure it 
can be repaired, just about everything about the radio can be.
>
> 5)  Is it safe to remove the front panel without the green gear? Any 
> other things I should be aware of?

I think you can pull the front panel without losing alignment.  You lose 
alignment when the RF deck comes out.  Even then, the green gear is a 
convenience, not a necessity.

Enjoy that radio - it sounds very nice!

Paul