[ARC5] Help Needed

[Ben Hall]

On 11/23/2014 2:50 AM, Joel R Roberts wrote:
> Greetings everyone, and happy Holidays. I was recently given a BC-348-R
> that looks to be internally intact, but is of course missing the
> Dynamotor and Filter assembly, and also the metal case. Does anyone know
> where I can find the values for the two filter chokes in the assembly?

Hi Joel,

Handbook, Maintenance Instructions for Radio Receivers BC-348-X, AN 
16-40BC224-3, available for download here: 
<http://www.jamminpower.com/main/bc348.html> notes the following:

Choke 301:  RF Choke for Dynamotor

COIL: r-f choke; 75 turns; #15 AWG enameled; layer wound; wound on maple 
or birch form measuring 3/4" long by 1/2" diam; inductance 83 
microhenries; d-c resistance 0.006 ohms; + 5% - 10% ; overall dimensions
3/4" length x 1 9/16" diam; mounts by a 1/4" bolt threaded into end of 
coil form; solder lug terminal at each end of coil form

Choke 302:  Filter for Dynamotor

COIL: r-f choke; wood core 1/2" diameter x 5/8" long; 300 turns #30 
single silk enameled wire; universal winding 3/16" thick; d-c resistance 
85.5 ohms +/- 5 ohms; terminal board with 3 terminals 1 3/8" x 1 3/8" by 
11/16", mounting screw through core

While the second listing doesn't note the inductance, using an air-core 
calculator (which isn't quite right for a wood core, but close-nuff I'd 
think) says 660 uH.

In my homebrew dynamotor replacement based on a DM-36 dynamotor with 
custom interface plate, I used 220 uH units in both positions and works 
fine when installed in the radio.

> As every one of the complete Dynamotor/Filter assembly's are scarce, and
> those we occasionally see on the bay are quickly driven out of my price
> range, similar to the Modulator/Dynamotor sets that a lot of us need, I
> am going to build up a substitute using the manuals and schematics that
> I currently have.

Which is what I have done.  :)

  If anyone has an extra case or knows the value of the
> chokes, let me know. I really appreciate the help. Thanks and 73's to
> all,,,,,,,Joel  KB0FPT

In the garage, I've got an extra case, stripped chassis, and stripped 
front panel (w/o holes).  The case is not drilled.  I was saving these 
for the next BC-348 I might run into...but that was like 5 years ago. 
Time to move it along to a new home.  Give me a shout off list direct.

thanks much and 73,
ben, kd5byb