[ARC5] BC-348 Dynamotors

[WA5CAB at cs.com]

Wayne,

Yes, all DM-28's are functionally interchangable.  The only critical 
requirement is that the B- not be grounded inside the dynamotor assembly (and of 
course that the electrical ratings be the same or close enough).  The 
B-supply differences between the JNQ and all other models are external.  However, 
it just occurs to me that I never actually looked into the cutout through the 
chassis of a JNQ that the filter cover drops into to confirm that there is 
clearance for the longer filter cover of the other models.  But I'm pretty 
sure that there is.  Just look down into that hole and make sure that nothing 
inside the length and width of the hole comes closer than about 3/4" of the 
plane of the underside of the chassis.  I have a receiver that I could look 
at but it's 2 miles and an hour and a half away.

In the BC-348-JNQ manuals, the asterisk in BC-348-(*) was actually supposed 
to mean J, N or Q, which are the ones that the manual writers made and 
sold.  The obvious difference between the DM-28-JNQ and the others is that the 
filter cover (box) is about half length on the JNQ and full length on the 
others.

FWIW, the dynamotor proper of the DM-36 is an electrical equivalent to the 
one on the DM-28.  Meaning same voltage and current ratings and floating B- 
brush.  It is physically smaller, being the same frame size as a DM-32.  Off 
hand, I don't know of another 28 volt one that is usable without 
modification.  There's not much call for DM-24's for BC-224, but the TCS receiver 
dynamotor would be a sub for it.  With the proper base and filter, of course.

In a message dated 10/21/2012 09:38:08 AM Central Daylight Time, 
releazer at earthlink.net writes: 
> have returned once more to my long term project of restoring a hacked 
> BC-348-J to its original configuration, or at least as close as I can get 
> within reason.  I have a question about the dynamotor subassembly that I hope 
> someone can answer.
> 
> Compared to the dynamotor employed by the other models, the dynamotor for 
> the J, N, and Q models has a different filter arrangement, as shown in the 
> manual.  I am planning to scratchbuild dynamotor packs and have already 
> wound my own filter coils, but I wonder if the dynamotors for the other models 
> will work in the J, N, and Q. 
> 
> I see nothing in the manuals that would indicate a restriction on which 
> DM-28 dynamotor can be used with which receiver.  In the J-N-Q manual the 
> dynamotor is called DM-28-*, presumably recognizing there are different 
> dynamotor models without specifying which one.
> 
> Any of y'all have any insight on this?
> 
> Thanks,
> 
> Wayne 
> 

Robert & Susan Downs - Houston
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