[R-390] starting 390A restoration

[nryan at mchsi.com]

Hi, Bob,

You're referring to the IF deck, not the RF deck, right?  The IF deck contains the "death cap."

You should replace any brown or black plastic-encased tubular caps, but keep the metal-encased ones except the "death cap."  That cap should be a high quality orange drop rated at 600VDC.

Replace out of spec resistors to optimize the unit and thus gain peace of mind.  I use original carbon comp type resistors.

Here's a link to helpful photos of a geartrain teardown from a fellow (I think) r-390 list member:
http://militaryradio.com/R390A/R390RFDeck/

Your PTO make is Motorola, but this link to a Cosmos PTO rebuild may be helpful:
http://r-390.com/cosmos.htm

Good luck,
Norman

Any activity becomes creative when the doer cares about doing it right, or doing it better. -- John Updike


----- Original Message -----
From: Bob Young <bobyoung53 at hotmail.com>
To: r-390 at mailman.qth.net
Sent: Sat, 1 Dec 2012 12:42:50 -0600 (CST)
Subject: [R-390] starting 390A restoration


I have a Motorola R-390A I bought some years ago and have finally decided to start to restore it. It will be my first 390A rebuild. Everything worked last time I powered it up but it needs mucho maintenance. I plan on taking apart the gear train, lube it adjust it etc with the help of the Y2K manual (which looks really well done by the way), also see if the PTO (Motorola) can be brought back to within specs without taking a turn off (doubt it, it's more than 10 Kc off end to end), recap it, align it and do anything else that needs to be done. I am reading (and reading) the R-390A Frequently Asked Questions Page but am sure I'll have a lot of questions. The first is I pulled the RF deck today to see if it had the death cap still in it and it does. I also noticed three or four brown beauties in there, probably a stupid question but should I replace those also? Resistor checks also? Thanks,

Bob Young
KB1OKL