Collins R-392?

[KF5UFA]

My R-390A just arrived at my home (I'm 100 miles away at work). I think I might be in for some work ahead of me.........but I'm feeling up for a good challenge.

Since it's missing one of the meters, and they're real hard to find, I'm thinking, instead of restoring it to original, put in things like the SSB card I've already purchased, set it up for DRM, and other digital modes. find other ways to interface it with my computer (OK, it will never be full-blown SDR, but so what.), probably change out the rectifier circuit for solid state (This was actually a modification in some military manual), maybe put in some LED indicator lights, etc. etc.











First, I've gotta get tho old gal working.

 

[mfn002]

My R-390A just arrived at my home (I'm 100 miles away at work). I think I might be in for some work ahead of me.........but I'm feeling up for a good challenge.

Since it's missing one of the meters, and they're real hard to find, I'm thinking, instead of restoring it to original, put in things like the SSB card I've already purchased, set it up for DRM, and other digital modes. find other ways to interface it with my computer (OK, it will never be full-blown SDR, but so what.), probably change out the rectifier circuit for solid state (This was actually a modification in some military manual), maybe put in some LED indicator lights, etc. etc.

First, I've gotta get tho old gal working.

Have you ever actually seen the inside of an R390A? In case you haven't, the tuning system is 100% mechanical and it uses a mechanical BFO for SSB.
One thing you are guaranteed to need to replace: the power supply filter caps (the two large ones on the audio deck). After a few years, these caps will start to leak, and will need replacing.
Also, for the antenna connections, there two, both of which are somewhat unusual: the first one looks like a standard PL259 except it has two pins instead of one. The other looks like an oversized BNC connector. The two-pin connector can be found on eBay for $10 or so.
Another word of warning: make 100% sure the crystal oven is set to "OFF". There is a rotary switch in the rear of the unit that controls this. The oven was intended to keep the crystals at a working temperature in subzero conditions. If the oven is on at room temperature, it'll fry the crystals. Also, DO NOT mess with the screw plungers on the tuning slugs. If you mess with those, it'll throw the radio out of alignment and you'll have to do a complicated process of re-alignment using a signal generator. On the other hand, if the radio isn't receiving properly, then you might want to play with those to see if that's the problem.

By the way, which meter is missing? You can get all sorts of parts for the 390A from here:
http://fairradio.com/

Here's a site you might find helpful:
The R-390A Frequently Asked Questions Page

 

[KF5UFA]

Have you ever actually seen the inside of an R390A? In case you haven't, the tuning system is 100% mechanical and it uses a mechanical BFO for SSB.

I'm somewhat familiar with the 390, having worked with them in the Navy. (It's been years!) I know that there is no reasonable way to control the tuning with a computer, but I'm sure I can hook up a computer controlled spectrum analyzer to it (I need one, anyway.). I have worked SSB with a 390, using the BFO, not unusual for a high end reciever of that era.

One thing you are guaranteed to need to replace: the power supply filter caps (the two large ones on the audio deck). After a few years, these caps will start to leak, and will need replacing.

SOP for just about any old tube gear. I may have to replace all of the electrolytic and paper caps.

Also, for the antenna connections, there two, both of which are somewhat unusual: the first one looks like a standard PL259 except it has two pins instead of one. The other looks like an oversized BNC connector. The two-pin connector can be found on eBay for $10 or so.

They are wanting $35 for this one on EBay: New R 390A R 390 R 391 Receiver Twinax Connector UG 970 U | eBay

Fair Radio sells those, I think. I might modify it to a plain, old SO-239.

Another word of warning: make 100% sure the crystal oven is set to "OFF". There is a rotary switch in the rear of the unit that controls this. The oven was intended to keep the crystals at a working temperature in subzero conditions. If the oven is on at room temperature, it'll fry the crystals.

They beat that into my head in the service!!!!!!

Also, DO NOT mess with the screw plungers on the tuning slugs. If you mess with those, it'll throw the radio out of alignment and you'll have to do a complicated process of re-alignment using a signal generator. On the other hand, if the radio isn't receiving properly, then you might want to play with those to see if that's the problem.

I have an awful feeling that I'll probably end up having to align the whole thing.

By the way, which meter is missing? You can get all sorts of parts for the 390A from here:
Fair Radio Sales Company Inc.

Here's a site you might find helpful:
The R-390A Frequently Asked Questions Page

The line meter.

I have Fair Radio bookmarked on my computer.

This one has been done very nicely, not Milspec paint, but really nice: Restored Collins Design R 390A URR Shortwave Ham Radio Receiver Communications | eBay