[ARC5] Dynamotors and receivers

[Kenneth G. Gordon]

On 9 Jun 2013 at 7:20, Mike Hanz wrote:

> On 6/9/2013 1:17 AM, Kenneth G. Gordon wrote:
> > Tonight, I tested an R-25 receiver I have been working on here by
> > powering it with a DM-34 dynamotor. I first cleaned then greased the
> > dynamotor's bearings with that grease that Mike Hanz recommended.
> 
> If you aren't already doing so, you might want to keep the tube of
> grease wrapped up in some paper towels and a plastic sack in your
> freezer.

I'll do that, Mike. Thanks for the suggestion.

>  It has a high oil saturation compared with other greases and
> will bleed on your shelf more, especially if you keep the tube in a
> vertical position.

...which I do.

>  Lowering the temperature and laying the tube
> horizontally will reduce that tendency.  In the tiny amounts present
> in a high speed motor bearing, the separation rate is optimal for
> lubrication, according to the Mobil engineer that I talked with about
> the tendency.

Good. I have several dynamotors here I need to service. 'll be using the info I 
got from you a long time ago from an ER article you wrote.

> > I was using clip-leads to connect everything together with. At
> > first, there was some minor "crackling" noticeable in the audio, but
> > when I connected the frame of the dynamotor to the chassis of the
> > receiver with another clip-lead, the crackling disappeared.
> 
> Heh, heh...great minds think alike, Ken... :-)   ARC began adding a
> small pair of copper straps to the postwar receivers on diagonal shock
> mounts to accomplish essentially the same thing.  I think they began
> the practice with the R-23A in 1945, so they must have noticed the
> same thing.

I have a couple of VERY derelict R-23s here with the remains of copper 
straps on two diagonally opposite dynamotor shocks.

That was kinda where I got the idea, Mike. ;-)

Ken W7EKB