crushed walnut shells and Tek 500 series scopes


Dennis – I hope you don’t consider this off topic. It is not on repairing a classic Tek scope – but an aspect on how they were made.

After reading the posting from the Peter Keller on the Coketron, it reminded me of another unique Tek process few know of, which I would like more details on The process is “sandblasting scopes with crushed with crushed walnut shells”.

Those who have seen the insides of any 500 series era Tek scope know the beauty of the ceramic strip construction hidden under the covers. The passive components and wiring harness are interconnected on a series of ceramic strips, with notches each containing a shiny fillet of silver bearing tin-lead solder. Have you ever wondered how Tek removed the solder rosin from the ceramic strips after assembly? There is no rosin showing on the ceramic strips, unless the scope has been repaired after it left the factory.

The solder rosin was removed from the ceramic strips with an air propelled abrasive cleaning method using – crushed walnut shells. It is similar to sand blasting, but with higher volume, lower pressure and lower velocity air. I was never able to see this in action while I worked at Tek, but many of the older engineers I worked with attested to the use of this process. (When I joined in 1978, Tek was still finishing up producing the last remaining type 1A1 plug-ins for a large long term contract with the US Army. I toured the production area, but did not see the cleaning operation at the time.) I know that the Tek Materials catalog had a Tek part number listed for crushed walnut shells used for this purpose. I was told that some delicate components, such as the beam lead Tek made TDs, special rubber covers were placed over the component prior to cleaning to prevent the lead being cut by the blast.

As I have never seen the operation, perhaps another member who has can answer these questions:
What was the size of the blast gun / nozzle?
How were the crushed shells removed from the scope after cleaning – vacuum cleaning?


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