Golborne Vintage Radio

I read about the Coketron on the TekScopes group on groups.io. The original is by Peter Keller who worked at Tek many years ago. There's a picture of typical Coketron here: https://www.sm5cbw.se/tubes/htm/coketron.htm

Quote:I guess it is time for the real story of the Coketron to be exposed.

The Coketron was originally developed for the cost reduction of the 545-B
with the new 545-C [ 545-C nomenclature - C for "Cokescope" ].

Advantages of the "Cokescope" included:

1.    Lower material cost - Coke bottles only cost a few cents vs. several
dollars for CRT bulbs.

2.    Independence from on-time supply issues caused by labor strikes at
Lancaster Glass and periodic flooding of the Corning Glass  plant by the
nearby Chemung River. Coke bottles were always available anywhere.

3.    Added employee benefits at Tek - the Coke bottles had to be emptied
by the bulb prep group before use.

The disadvantages that caused the program to be cancelled were pattern
distortions and how-the-heck do you paint the accelerator helix on the
double reentrant curve of the bottle? Also, the glass 2-liter Coke bottles
necessary to better fill the big round hole in the 545-C front panel were
not yet perfected. 2-liter plastic Coke bottles were tried but they tended
to sag into strange shapes at bake-out.

Seriously though, Tom Lee was closest.

Two Coketrons were made several years apart in the Engineering Tube Lab just
to show that it could be done. The first used a T3100 or T3160 gun and
worked surprisingly well. I can remember it displaying the crosshatch
pattern generated by the CRT engineering B2 test sets. Unfortunately, the
tube later rolled off a bench and failed the impromptu drop test. I believe
it was during a lab move.

The second tube used a T2110 gun and suffered a cracked bulb due to thermal
coefficient mismatch of the glasses during processing. This was repaired and
became the tube pictured in my book. This one did not have phosphor on the
screen but glass fluorescence would usually suffice to display a trace. Both
tubes did have complete electron guns with deflection plates. I can't recall
the second tube actually being operated but excessive gas levels due to
little or no bake-out because of the TC mismatch might have been the reason.
I remember it was mainly constructed for photos since we had none of the
first tube.

There you have the rest of the stories. Take your pick!

All of this was 30+ years ago so memories are a little fuzzy.

Peter Keller

That's brilliant!

I like things made from items which would otherwise be scrapped - gives them a new lease of life!

Thanks for putting it up, Jeffrey!

"Unfortunately, the
tube later rolled off a bench and failed the impromptu drop test. I believe
it was during a lab move."

Is that not the reason why CRTs are made tapered to ensure that they roll in a circle?

Peter

I remember that the late and much missed Brian Cuff dropped something on the neck of a pre-war CRT. The CRT failed the impromptu impact test. Whoops!

(16-01-2021, 11:39 AM)ppppenguin Wrote: [ -> ]I remember that the late and much missed Brian Cuff dropped something on the neck of a pre-war CRT. The CRT failed the impromptu  impact test. Whoops!

I was there.
We were using the lathe together in his metalwork shop - otherwise known as the garage. Brian had the pre-war (fully working) CRT stored on the floor in the corner, neck upwards, sadly unprotected. As we were were working away we heard a clink, followed by what sounded like a sheaf of brass shim stock falling on the floor. Perplexed, we looked round and saw nothing. Until, that is, Brian looked over at the CRT. He really did go white, but no profanities passed his gentlemanly lips. There may perhaps have been an "Oh dear, Oh no." and a very deep sigh.
A section of 1/4" brass rod only a few inches long had rolled off a high cupboard, helped by the lathe's vibrations. It had pirouetted in the air and landed exactly end on, precisely in the middle of the tube base connector. The base would have protected the evacuation pip if the rod had landed in any other way!
On inspection, the CRT had a collection of bits of loose phosphor visible inside, and was clearly now open to air.
Brian was magnificent. He shed no tears, although clearly saddened and shaken, and simply suggested we break for tea. We soon went on with my lesson on the lathe.
I miss Brian a lot.
-Jeremy