[time-nuts] General Technology Corp model 304b

Ed Palmer ed_palmer at sasktel.net
Sun Apr 29 18:36:17 UTC 2012


Hi Don,

You know that we're going to be swapping many emails, don't you? :-)

On 4/29/2012 11:16 AM, Donald Henderickx wrote:
> After following Ed Palmer's thread on 304b restoration,I was inspired 
> to get my GTC (tracor) 304b ser#279 going.  It seems that the failure 
> of this unit was the break down of the foam that was wrapped around 
> the vcxo located inside the control box. The vapors or the moisture 
> the foam collected corroded the steel fasteners and caused the 
> switches to become intermittent.

The foam around my OCXO is still in great shape.  Still spongy and 
providing lots of holding force for the OCXO.  My unit is serial #449.

> The replacement of the foam in the control box is not that much of a 
> problem,what I need help with is what to use around the Rb lamp base. 
> The foam has turned to powder. 

Do you mean foam around the back end of the lamp where the wire lead 
comes out or the foam that surrounds the reflector (#16 in the picture 
in the patent that describes the lamp (3311775))?  My #16 foam is really 
solid.

> Should I try Home foam sealant? The cell's ,of this seem about the 
> same as the old foam.Will it take the heat?Should I make a fiberglass 
> cocoon to put around the lamp base.

Read the fine print on the can.  It may list the maximum temperature 
rating.  I'd try a fiberglass cocoon first just because it's easily 
reversible if it doesn't work.  When your unit is running is the lamp 
test point voltage correct?

Ed

> The unit now achieves lock in about an hour. The only other thing I 
> did was to replace the caps in the main supply.
> Any thoughts on the insulation?
> Don H



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