[ARC5] Dynamotors.

Sat Feb 21 10:36:46 EST 2015

You mention battery drain in a mobile situation.  A problem, for sure; but not your only problem.  Dynamotors are tough on automotive voltage regulators and the diodes in alternators.  I speak from experience.  My first rig on Dos Metros was a GE 15-watt taxicab radio converted to 12 volts, with a TCS dyno powering the transmitter side.  It ate 3 voltage regulators and 2 alternators over about a year and a half. 

And, with all the electronics in today's cars, the inductive kicks could add more not-so-welcome consequences; you will have to take steps to suppress those.
The agency I work for has not used any dyno gear in decades; and the last all-tube gear with T-power supplies included the GE Progress Line and the Motorola T71**T (I forget exact letters).  Both used either a pair of 6146s or maybe a 5894 (or similar tube) in the PA, at 100 watt output. (I do know that some of the first 100-watt GE Prog rigs they used were dyno powered; I've seen a couple... Heavy?  You don't wanna know....!)  The last of these were just a few years prior to my time; but the anecdotal history (fancy words for shop stories) says they were a lot less trouble.  I once played around with an old Link 35UFM transmitter and 11UF receiver from the pioneer days, which had been converted to 12 volts back in the mid to late fifties, and got them working... the dynamotor in that transmitter was not mil-surplus but a Carter of some type, square-looking design.  Start current was high enough that it would shut down the bench power supplies unless a car battery was floated across them.

73
Mike
WA4DLF

      From: J Mcvey <ac2eu at yahoo.com>
 To: Mike Everette <radiocompass at yahoo.com>; "kgordon2006 at frontier.com" <kgordon2006 at frontier.com> 
Cc: ARC-5 List <arc5 at mailman.qth.net> 
 Sent: Friday, February 20, 2015 9:53 AM
 Subject: Re: [ARC5] Dynamotors.

I found this wiki on the scr-508 which mentions the dynamotor input voltages, but not the output,
SCR-508 - Wikipedia, the free encyclopedia
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| SCR-508 - Wikipedia, the free encyclopediaThe SCR-508 Radio was a mobile Signal Corps Radio used by the U.S. Army during World War II, for short range ground communications. The SCR-508 seri... |
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| View on en.wikipedia.org | Preview by Yahoo |
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  Then I found a picture of a DM-35 plate on Ebay:
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| DM-35 Dynamotor for Radio receiver BC-603 p/o SCR-5...US $74.00 Used in Collectibles, Militaria, Surplus |
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| View on www.ebay.com | Preview by Yahoo |
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  DM-35 Dynamotor for Radio receiver BC-603 p/o SCR-508 Signal Corps US Army

 Bottom line: the DM-35 specs are  12v @18.7A imput with 625v at 225 ma output.This is rather large for the ARC5 requirements, but will definitely work. 
The DM-33 (original tx supply for ARC-5 and SCR-274 series) was rated at 575V @ 160  ma continuous. 

My objective is to find a dynamotor with least possible in/out current that will still be able to properly supply the transmitter. Battery drain could be a real problem in a mobile situation...

The dyno that I have, D401, has a plate that says 12v at 9.9a input and 440v@ 180 ma out.It takes about 25-30 amps to start, then it idles at about 3.75 amps. Of coarse it will draw at or near the 9.9A under load.I like the way they sound when they spool up to speed in an instant.
     On Thursday, February 19, 2015 9:49 PM, Mike Everette <radiocompass at yahoo.com> wrote:

 The first thing I thought of when reading this post, was the DM-35 dynamotor from the BC-604/684 tank transmitter.  I doubt the Navy used them but the USMC may have.  (And what does "MARINES" stand for?  "My Ass Rides In Navy Equipment, Sir!")

The actual dynamotor for the DM-35 is about the same physical size as the DM-33 or DY-8/ARC-5.  The base is quite different, though.

Do the dynamotor bases have large Jones type connectors on them?  If so they may be DM-35s.  The connectors were used for input and output, of course, plus the jumpers that configured the transmitters for 12 volt or 24 volt.  The 24 volt counterpart to the DM-35 is the DM-37.
As for those two 6 volt motors in series input and parallel output... imagine the current draw!  And, you'd probably have some interesting experiences with "inductive kicks" especially on start-up.
73
MikeWA4DLF

      From: Kenneth G. Gordon <kgordon2006 at frontier.com>
 To: J Mcvey <ac2eu at yahoo.com> 
Cc: ARC-5 List <arc5 at mailman.qth.net> 
 Sent: Thursday, February 19, 2015 7:20 PM
 Subject: Re: [ARC5] Dynamotors.

On 19 Feb 2015 at 21:52, J Mcvey wrote:

> 
> "I also have two "new" 12VDC input, 600 VDC at 200 mA output dynamotors 
> I'll use for the transmitters."
> 
> Could you share the model number of this dynamotor? What system is is it 
> from?  My scr-274 series are converted to 12V, but the dynamotor that I have is
> only 440 volts, @ 200 ma. That's all I could find...

Sure. I have two: they are both Stromberg-Carlson Dynamotor 42486, 12V 
16.8 amps input, 680 VDC at 210 mA output, MPF-4-45. 

These were made by Webster Products

They have the US Navy anchor stamp on them. Neither one have the 
end-bells on them, so I am going to have to make some new ones for them 
before I use them. They have never been used.

These were part of a load of "junque" I got from our University's EE 
department when they were cleaning a bunch of that out.

They were obviously for some sort of military, U.S. Navy, transmitter, but I 
have no idea which one.

Maybe WA5CAB might know.

I did a search on eBay for dynamotors too, and found two 12V jobs which 
output 500 VDC at 200 mA.

I also found two 6V input jobs which output 600 VDC at 200 mA. I suppose 
you could connect the inputs in series and the outputs in parallel...

Ken W7EKB
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