On Jul 13, 2:09*pm, (Scott Dorsey) wrote:
Engineer wrote:

Results, all good:
-- took off end caps, very clean inside, no rust
-- freed-up armature by hand, moved easily, not stuck

So fasr so good.

-- removed bearing end plates, bearing grease looked a bit congealed,
added some "electric motor" oil to thin it a bit

You want to scrape it out and put new grease in there if you can, if only
because modern grease is a lot more stable and will make the bearings last
longer than the original stuff.

-- commutator and brushes in perfect shape - factory new, of course
(there are several new brushes in small metal cans actually stored in
each end of the dynamotor - great idea!)

This is a standard military thing.... you should have spare fuses somewhere
also.

-- powered it up unloaded on var. DC supply, it started to turn at
below 12 VDC (I did not record the exact value), ran it up to 28 VDC,
about 262 VDC open circuit on the B+ supply line
-- added 10 Kohm load to B+ line, 255 VDC loaded (~ 25 mA DC)
-- ran unit for 1/2 hour to mix the bearing lube and polish
commutators/brushes
-- unit now starts to turn at 2.6 VDC (unloaded)
-- reassembled and put back in chassis pending radio test.

Sounds excellent!
--scott

--
"C'est un Nagra. *C'est suisse, et tres, tres precis."

Thanks, Scott. I'll do a lube job - I'm restoring these things for
the next 100+ years!
Cheers,
Roger