[ARC5] More dynamotors

[Charles]

Today I went back to the flea market where I got the original Navy 6-9 Mc 
receiver and coverless, tubeless 7-9.1 Mc transmitter, and purchased the 
remaining two mil radio items from that booth:

1) a very clean DM-35-D dynamotor (12 volt in, 625V @ 225 ma out) on a base 
with two hefty Jones-type plugs, and
2) a radio subchassis I can't identify, but it's MFP coated and has the 
"standard" 28V in, 250V @ 60 ma dynamotor. Lots of 6AG5 and 6J6 tubes and a 
Jones plug on a pigtail harness.

The DM-35 has the original safety wires on the end cap screws, so I applied 
12v only for a few seconds and it spun right up to 625 volts output. That's 
enough testing since the bearing grease is almost certainly 70+ years old 
and solidified. Anyone have a need for it? It seems to be used in a BC-603 
tank transmitter... Make me any reasonable offer - it's heavy though, so 
shipping might be considerable. I just looked on ebay and there's one that 
looks new-in-box in the Netherlands right now with two bids - at $80! Seems 
awfully high to me.

Then I dismounted the receiver dynamotor with its cast mounting base from 
the subchassis, removed the end caps, and inside were stenciled lubrication 
instructions. "Remove as much of the old grease as possible, apply "M-G 
Grease" to fill end cap. Do not pack bearings, do not get on commutator". So 
I did, using a light synthetic grease. Also checked to make sure all four 
brushes were loose in their holders. Then applied 24 volts and it spun right 
up to 250v open, 235v into a 5K load. Now up on the bench running unloaded 
for a while :)

Now I just have to fabricate a base plate with an octal plug to match my 
"hacked" 3-6 Mc receiver which has the dynamotor plug replaced by an octal 
socket (looks like the hole was rat-tailed larger so even if I found an 
original dyno plug it wouldn't fit. The shock mounts, surprisingly, are 
still there and not totally disintegrated, so I plan to use E-clips to mount 
the new base plate.

-Charles
WB3JOK/0