[R-390] Tube removal

[Barry]

In a pinch (no pun intended), I would think that a pair of common kitchen scissor-style tongs with some shrink wrap or thin rubber tubing wrapped around the ends would work as well.

I have some of the older Tektronix items (Type 106, Type 191 as well as a Type 184 which uses nuvistors).  The 106 and 191 have tubes with IERC shields.  I tried to remove one of those shields in the 106 and I simply could not pull it loose.  I've used IERC shields before and they can be tough to pull when they're locked to the tube base (which they should be to work properly) but I simply could not pull hard enough to remove them in the 106!

Thanks,
Barry - N4BUQ

----- Original Message -----
> From: "Tisha Hayes" <tisha.hayes at gmail.com>
> To: "R-390 Mailing List" <r-390 at mailman.qth.net>
> Sent: Thursday, January 6, 2022 9:52:34 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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