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Title: MYSTERY TUBE Post by: KB5MD on March 02, 2018, 07:33:03 PM I am beginning restoration on a Hallicrafters HT33A linear amp and have found that the original tube (PL-172) and socket have been replaced by the one shown in
the picture. There are no markings on the tube and it is a little smaller than the original. Anyone have any ideas? Title: Re: MYSTERY TUBE Post by: w8khk on March 02, 2018, 07:36:00 PM I also restored an HT-33A. PL172 from Penta was good tube.
Yours looks a lot like an Eimac 4CX1000A. https://frank.pocnet.net/sheets/140/8/8168.pdf http://www.cpii.com/docs/datasheets/213/4CX1000A.pdf Title: Re: MYSTERY TUBE Post by: w4bfs on March 03, 2018, 04:33:05 AM measure the filament voltage to see .... be careful of differences in the 4cx1000 family (A or B)
Title: Re: MYSTERY TUBE Post by: KD6VXI on March 03, 2018, 11:54:14 AM Definitely looks 4cx1Kish .... I have two variants here, one Eimac and one English Valve Co. Although slightly different cosmetically, same physically, give or take.
--Shane KD6VXI Title: Re: MYSTERY TUBE Post by: WBear2GCR on March 04, 2018, 04:18:40 PM I think if I owned that linear, I'd get one of those nice Ruskie ceramic tubes & sockets, buy a spare and transplant it in!:D _-_- |