[R-390] Tube removal

[Jim Whartenby]

TishaYour July, 2009 IERC data for the SP-600 can be found here:
https://doczz.net/doc/2327893/revised--4-18-06---the-hammarlund-historian
Happy New Year,Jim

Too much agreement kills a chat.  E. Cleaver

-----Original Message-----
From: Tisha Hayes <tisha.hayes at gmail.com>
To: R390A <r-390 at mailman.qth.net>
Sent: Thu, Jan 6, 2022 9:52 am
Subject: [R-390] Tube removal

Those "Chinese finger-puzzle" type of grips are still used but on cables;
You will find them for suspending coax cables inside of cellular towers
from the top and along the midspan. They are known as "Kellum grips".

Now, a Kellum grip used for cabling might be a bit too "aggressive" but
glass is amazingly resilient when forces are applied equally around their
radius. You would need to find a light-duty one.

The gorilla tape is a great idea; You can always remove the adhesive from
Gorilla tape with the universal solvent... WD-40.

Another alternative would be to find an "IERC tube shield".  Those are as
rare as hen's-teeth and quite valuable in the tube-radio market. They are a
black metallic shield that slides down over the top of a tube and are used
for shielding and thermal dissipation. They have beryllium-copper
fingerstock inside of the shields that tightly grabs the tube glass and
couples the heat to the metal shield. If you could slide an IERC shield
down over the tube you could then grab the top lip of the shield with a
pair of needle-nose pliers and rock the tube up and out of the socket in a
confined space.

A bunch of years past I did a writeup on the thermal improvements in a
Hammarlund SP-600 (posted on a different list) between unshielded tubes,
silver-metallic shielded tubes and IERC shielded tubes on an SP-600 that
was installed in a closed cabinet. It involved thermocouples attached to
the chassis and key components in multiple locations, regulated AC
supplies, temperature controlled rooms and a few weeks of data collection.
The end result was that the IERC shields did knock down the temperature of
the chassis by an average of 5c to 15c.  The purpose was in how such
temperature reduction would have on extending the life of components like
electrolytic capacitors and on frequency drift of the receiver. I do not
even have the writeup or data any more; it was lost in one of the many hard
drive failures that we all experience with computers.

I did end up buying a significant quantity of IERC shields and they are
still installed on my SP-600-JX17, R-390A and the much despised (by me)
CV-591 SSB converter.

*Ms. Tisha Hayes*

*AA4HA*
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