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Title: 4D32 mounting question Post by: WA4WAX on September 20, 2019, 07:39:22 PM Hello all!
THe 4D32 data sheet states that the shield disc should be at or below the chassis in order to isiolate plate and grid circuitry. I have some NOS 4D32, and am thinking of putting a transmitter together. I have never used the 4D32, but it has appeal. There are two discs in the lower part of the tube. Which of these is the "shield disc", the upper or the lower? Thanks! Title: Re: 4D32 mounting question Post by: PA0NVD on September 20, 2019, 08:11:12 PM Surplus sales of Nebraska has these sockets, they are already sunk to the correct altitude below the chassis
Title: Re: 4D32 mounting question Post by: WA4WAX on September 20, 2019, 11:11:41 PM Thanks Nico, but I have several standard porcelain septar sockets.
I simply need to now which disc is the Shield disc. Title: Re: 4D32 mounting question Post by: PA0NVD on September 20, 2019, 11:26:26 PM I do not know this tube. The shield disk is normally the support disk for the second grid. So follow the pins of G@ and see where they are connected to
Title: Re: 4D32 mounting question Post by: KC2ZFA on September 21, 2019, 10:24:25 AM look below, one of the disks is probably a mica sheet. Level on the metal disk.
Title: Re: 4D32 mounting question Post by: PA0NVD on September 21, 2019, 10:40:17 AM It looks clearly like the lower disk. That one seems to be connected to the screen grid structure
Title: Re: 4D32 mounting question Post by: WA4WAX on September 21, 2019, 01:54:21 PM The lower one it is! The upper one appears to be Mica in the X Ray image.
Thanks to all! Title: Re: 4D32 mounting question Post by: Opcom on September 22, 2019, 02:14:08 AM look below, one of the disks is probably a mica sheet. Level on the metal disk. Just from curiosity, what KVP and duration was used to get that X ray? Title: Re: 4D32 mounting question Post by: KC2ZFA on September 22, 2019, 08:17:04 AM this is where it’s from https://www.audioasylum.com/audio/tubes/messages/26/262672.html
Title: Re: 4D32 mounting question Post by: Tom WA3KLR on September 22, 2019, 08:32:22 AM Hi everyone. I just looked at this thread for the first time. I had a Collins 32V-3 and several spare 4D32's for many years, As I recall, I saw an internal mica screen bypass capacitor, so there is very little parasitic series inductance for this first amount of bypass. It is not a large value but excellent screen bypassing is important for best tetrode/pentode performance. I think I measured around 200 pf? (This was ~25 years ago) I guess the designers were pushing the VHF performance for some contract. I have always been impressed with this tube's design. Hats off to the Raytheon engineers.
Title: Re: 4D32 mounting question Post by: n4wc on September 22, 2019, 09:57:32 AM Take a look at the Halli HT 20.
They put a ~1/2 inch band around the bottom of the 4D32 riveted to the chassis/tube socket(johnson brand) Title: Re: 4D32 mounting question Post by: w4bfs on September 22, 2019, 02:15:09 PM EFJ used this tube in the viking1 and the porcelan socket was flush mounted t0 the chassis .... maybe we can get Brett to get off his motorcycle and weigh in ;D AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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