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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