[Collins] R-390/A help

[Dr. Gerald N. Johnson]

They might be hard to find. Fair Radio shows pictures but they are out 
of stock. I've used rubber ones most of my life, but they are probably 
getting hard and won't work so well.  Basically the wire ones for the 
R390A are chinese finger catchers. They might be woven of wire or bamboo.

Back in the late 50s my dad (K0CPN) made one for a tube deep inside the 
VFO of a Viking Ranger where the supplied shield was folded backwards 
making normal access to the VFO tube impossible. So he cut a hole in the 
top shield and bolted on a patch. For a tube puller he used a bit of 
1/4" or smaller copper tubing with a slot cut about half way through and 
3/8" or so from the end of the tube. He passed a bit of sturdy cord as a 
U loop from the long end of the tube and out the notch. That loop could 
be slipped around the tube envelope and tightened up by pulling the open 
ends up top and allowed replacing the tube. For the tight spaces in the 
390 it might need to be made of flat (or small rectangular or airfoil 
shaped) model brass tubing. Dial cord would be a good string material. 
You want the loop to make its plane perpendicular to the axis of the 
tubing so the slot needs to be across the tubing, not up and down. Else 
it will turn the tube in a way you don't want but a wire loop loose on 
the tube envelope could be soldered to the tubing to keep the vacuum 
tube in line. Otherwise its basically a tubing supported sideways noose. 
Its important that the inside of the slot be smoothed so it doesn't cut 
the cord.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.

On 12/17/2011 7:44 PM, L D Ritta wrote:
>
> Hello Everyone
>
> I have the need for a 7 pin tube puller, as used in the Collins R-390,
> please email, if you can help.
>
> 73's Lee.
>
>