[ARC5] [Milsurplus] BC-348 power

[Meir WF2U]

John,

I have the schematics for the Russian issue solid-state inverter for the
US-9. The catch is that there are no specifications/data for the
transformer.
  
Here is another approach for using an existing surplus US military
solid-state inverter module as a substitution for the BC-348/US-9 dynamotor.

 Although the original idea came from the R-683/ARR-41 dyno substitution: 
http://staff.salisbury.edu/~rafantini/ARR41modifications.htm , the same
inverter module with the modifications mentioned in the link can be used for
the BC-348/US-9, except the center tap of the high voltage winding of the
transformer shouldn't be grounded. These inverter modules from the ARC-51
UHF surplus transceivers are available from Fair Radio for $25. I tried one
in a BC-348, it works great. No extra RFI filtering is needed. I showed the
setup to someone else in my ham club who needed a dynamotor for his BC-348,
and he used the inverter with very satisfactory results as well. The
inverter footprint fits the BC-348/US-9 dynamotor footprint.


73, Meir   WF2U

Landrum, SC  

-----Original Message-----
From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of
John Watkins via Milsurplus
Sent: Sunday, November 23, 2014 4:53 PM
To: Ben Hall
Cc: arc5 at mailman.qth.net; Army Radios; joelroberts001 at comcast.net; Mil
Surplus
Subject: [Milsurplus] BC-348 power

I have a Soviet US-9 ( copy of the BC-348R ) built in 1976 and in flight ops
until around 2005, with a solid state supply replacing the Dynamotor.   Also
have the manual and it lists the parts.  If anyone wants to build a
replacement for the DM-28 Dynamotor supply, I can hunt up the manual and
post it on the site.  I think Meir also has some info on this.  It can
directly replace the DM-28 and vice versa.  I could also use a base for the
DM-28 for my BC-348Q that I am restoring.

John. WD5ENU

Sent from my iPad

On Nov 23, 2014, at 8:41, Ben Hall <kd5byb at gmail.com> wrote:

> 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
> 
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