Quote:
Originally Posted by Phil Nelson
I'm working on a Dumont RA-102 that has a 12JP4 picture tube. I have a chance to get a 12KP4A and I'm wondering if that's a good sub, as it seems to be from these data sheets:
http://frank.pocnet.net/sheets/127/1/12JP4.pdf
http://frank.pocnet.net/sheets/127/1/12KP4A.pdf
Nothing really wrong with my 12JP4, but this CRT is not aluminized and it doesn't use a bent gun, so it develops ion burn over time.
Unless I'm missing something, the 12KP4A is aluminized, eliminating the ion burn problem and possibly giving a little brighter picture. It also has an external aquadag coating, while the 12JP4 does not, but that's no big deal.
Regards,
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html |
Phil,
Look at the physical dimensions and bulb shape of the 2 tubes, I found out the hard way they aren't completely interchangeable. I restored a RA-103 in a large Chinese decorated cabinet, the customer left me just the chassis as he was getting the cabinet restored. The 12JP4 was bad and the "spare" was also bad so I figured a 12LP4 would work OK, and it did as far as the chassis was concerned. When he tried to install the chassis with the new tube back in the cabinet we found that the difference in the 12LP4 bulb shape and the mask shape weren't compatible and the chassis wouldn't slide all the way into the cabinet. We had to have the depth of the mask cut down to fit the shape of the 12LP4, this allowed the chassis to slide all the way into the cabinet.
Chuck