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 Post subject: 1951 Zenith 19 inch Porthole Television
PostPosted: Nov Mon 04, 2019 4:44 am 
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Joined: Jan Thu 19, 2017 4:39 am
Posts: 2
I recently acquired a 1951 Zenith 19 inch Porthole Television and found someone that has worked with these to help me get it up and running again. Unfortunately the first thing we found was a dead picture tube.

So...here is my question....Where can I find a new 19 inch Zenith Portal picture tube???
The tube currently in the TV is a Rauland 19AP4B

Any ideas would be appreciated.

Thank you,
Bryan


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 Post subject: Re: 1951 Zenith 19 inch Porthole Television
PostPosted: Nov Mon 04, 2019 5:25 am 
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Joined: Apr Sat 29, 2017 6:22 pm
Posts: 135
Check if The early television museum has one, if not, post an ad in the classifieds.


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 Post subject: Re: 1951 Zenith 19 inch Porthole Television
PostPosted: Nov Mon 04, 2019 4:53 pm 
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Joined: Nov Thu 11, 2010 6:03 pm
Posts: 971
Location: Pewaukee, WI
19" metal tubes are getting scarse and have a propensity for vacuum leaks that make them too gassy to operate (in addition to the Cathode emission surface wearout common in all CRTs that have seen a lot of on time).

Did you see him test it and what the readings were? It is and was common for shops that don't want to work on a set to falsely tell the customer bad CRT to scare them off or learn that money is no object for the customer....
How many monochrome CRT sets from the era has the tech restored, and how many have they tested the CRTs on? A weak testing monochrome CRT that moves the needle part way into the bad range of a CRT tester will usually produce a good picture that won't be good for daytime viewing if a lot of daylight is in the room but will look splended at night with average to subdued room lighting. ( The good-bad scale on most CRT testers is calibrated for color CRTs which need much stronger emission to counter the losses from emission being absorbed in the shadow mask). If the tube is weak but not stone dead it will be fine to use. Also some CRTs that haven't been used in years will play dead for the first 2min-2 hours of being powered up (collectors call it the CRT being asleep) if it comes up to good emission after 2 hours testing the CRT is good to use (and should warm up at the normal designed rate if used atleast once every couple months.
New or old CRT you have to worry about gas... some testers are very vague about indicating a gassy tube. Gassy CRTs will usually test VERY strong in the emission department (regardless of actual cathode condition).


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