The AM Forum

GE, I’m hoping that u can answer my question or direct me to a ham that can. I have been trying, to no avail, to find the nomenclature for the mic and speaker that was used with the Collins BC-398-R. Any guidance would be greatly appreciated.
Tnx es 73 de Bob KD2NFS

I don't find this model quickly. What was it used for or installed in, and how old is it?

Are you talking about the BC-348 R?, been doing this stuff for a while now and never run across the BC-398. If it is the BC-348 think by using the correct number you will find there is lots of information on that receiver and its interconnection with the ART-13 in whats known as the ARC-8

https://aafradio.org/flightdeck/b29.htm
The link is to a B-29 radio deck picture that has the items marked. Look down the page at the all the "goodies". :) I don't see a speaker. It may be that there was no speaker used due to the noise level in an aircraft.
I would suggest that you look for pictures that list the radio equipment in various WWII aircraft to see what you can find.
What do I use on my BC-348-R? A LS-454/U speaker.

Bill KA8WTK

BC-348 was never made by Collins.  Depending on suffix you got Belmont, Stromberg-Carlson, Wells Gardner or RCA.

If you have an untouched "R" you will find all the Micamold brand paper capacitors to be bad and they need to be changed.  These are the larger black domino looking ones usually on the terminal boards.  Lately the APC variable trimmer capacitors sticking out from the rear boxes are having their shaft collars break, which causes them to collapse the rotor into the stator and short out. I rob collars from junkbox caps to fix this but it is annoying to deal with.

Other than that, just make sure your AC supply, if you build one, doesn't return B- to the chassis and you should be good to go.  I usually do a brief run-through of the resistors with a DMM on auto-range to check if any are open or too high.  No usual need to unhook one leg of them.

These usually still have that "surplus smell" when you pull the chassis from the cabinet.

The other receiver used with the ART-13 at war's end and later was the autotune ARR-15.  Rare and with some issues all its own. I am restoring a couple of those now but I think I will always like the BC-348 instead.

depends on where you are located, Its a easy radio to work on and just about all the parts it uses are available without too much trouble. Restoration can get hairy being a lot of people thees days are into it has to be exactly like it was when in some big WW2 bomber with the dynamotor and all that but i ten to like to see them more along the lines of what they were in the Ham community in the fifties, sixties and seventies.
My first real Short Wave receiver was a BC-348 back in the seventies back when I was a punk kid, and I learned a lot working on that radio so I tent to think the best example is what the old CQ Surplus Conversion Manual (1948) would have you do with the internal AC power supply, S meter and low impedance audio output transformer for driving a regular 8 Ohm speaker.
Got a video I did years ago on that radio over on YouTube of a 348 I did back ten or so years ago and every now and then people piss and moan about my "Hack Job" but the hell with them. Its my radio insist it?

https://www.youtube.com/watch?v=YKRez8euQU4

Do you want to get the radio working or do a restoration? think with the people around here can assist with getting it up and running without much trouble. Whats the receiver do now?

If you're in Long Island, you might want to contact the N.J. Antique Radio Club. While it's a N.J. club, there are some members who live on the other side of the Hudson. Perhaps there's a member who could help you out. From the days when I was starting out, I remember that radio/TV shops never seemed to want to touch military gear.

http://njarc.org/

do you know how to read a schematic? have a VOM? the basic AC power supply that was installed in most conversions is straight forward. the trick is that you had to also change the filament distribution so the the tubes all work from 6.3 volts.
When you turn the radio on do the tubes light up? or do they stay cold? that's like step one in diagnosing the power supply.