Old Muntz TV for sale Locally to me, Should I pick it up?

[vortalexfan]

Originally Posted by old_coot88

Some doorknob resources here - https://www.bing.com/search?q=doorkn...BLH&sp=1&ghc=1

Actually doorknobs in TV sets fell out of vogue in the early '50s, as all-glass CRTs phased out the old metal bell types. Glass tubes, by dint of inner and outer dag coatings, provided their own HV filtering, so doorknobs weren't needed. But out of convention, some mfrs continued using doorknobs for a while anyway.

OK, so that must of been the way it was with Meck I'm assuming, they were one of the companies that still continued to use doorknob capacitors in TVs even after they were no longer required in TVs...

[Electronic M]

Originally Posted by vortalexfan

OK, so that must of been the way it was with Meck I'm assuming, they were one of the companies that still continued to use doorknob capacitors in TVs even after they were no longer required in TVs...

The 10" and 12" glass CRTs didn't need the doorknob, but many chassis of the day were designed to drive both of those and a 16" metal cone CRT....it was less of a production hasto to make a chassis that drove some glass and some metal CRTs have the cap in the HV cage regardless of the CRT type than pick and choose a flavors of basically identical chassis off the line.

Doorknobs continued in color TVs (which had metal cones later) until around 1956...the RCA TM-21 broadcast monitor had one and was built into the 60s.

Doorknobs are still made today for X-ray machines (based on the datasheets) and we're stocked by mouser and digikey when I last need to order one a year ago....they are very expensive. Also there's really only 2 choices in physical mounting: ASE or metric thread on the bolt holes in the terminals...If you need a terminal to be a stem or something special you have to machine something that will do the job and thread into the cap you get....I had to do a good bit of clever fabrication to fit the 3 replacement doorknobs I installed in my RCA 21CT55...

If your CRT has outer dag and a ground spring making good contact between it and chassis you could probably get away with just flat out removing the doorknob and not replacing it...

[vortalexfan]

Originally Posted by Electronic M

The 10" and 12" glass CRTs didn't need the doorknob, but many chassis of the day were designed to drive both of those and a 16" metal cone CRT....it was less of a production hasto to make a chassis that drove some glass and some metal CRTs have the cap in the HV cage regardless of the CRT type than pick and choose a flavors of basically identical chassis off the line.

Doorknobs continued in color TVs (which had metal cones later) until around 1956...the RCA TM-21 broadcast monitor had one and was built into the 60s.

Doorknobs are still made today for X-ray machines (based on the datasheets) and we're stocked by mouser and digikey when I last need to order one a year ago....they are very expensive. Also there's really only 2 choices in physical mounting: ASE or metric thread on the bolt holes in the terminals...If you need a terminal to be a stem or something special you have to machine something that will do the job and thread into the cap you get....I had to do a good bit of clever fabrication to fit the 3 replacement doorknobs I installed in my RCA 21CT55...

If your CRT has outer dag and a ground spring making good contact between it and chassis you could probably get away with just flat out removing the doorknob and not replacing it...

My picture tube I believe does have an outer dag coating and some ground springs, so maybe I can just remove the doorknob capacitor in my tv altogether and just wire the new 1 Megaohm 1 Watt resistor from the 1B3 socket straight to the high voltage anode via a terminal strip bolted to the old doorknob capacitor hardware.
Because I looked at the price of a 500pF 15kV doorknob capacitor and they're over $100 a pop!