BIG vacuum tube

[k7mdo]

I was offered the opportunity to clean out a SK's collection from the '40's to date.  There is/was a tremendous amount of large scale projects and he was quite an active ham (W7HU) in the 60's.

One item caught my eye before it headed toward the dumpster:  A vey large vacuum tube with USN designation: CG-851

I was unable to find internet ID's in a quick search and wondered if any of you folks can shed light on its application/use?

73, Tom

[Tom WA3KLR]

Tom,

I checked my 'Tube Lore' book by Ludwell Sibley. That is a Navy number, prior to 1942, before the military adopted the Army/Navy numbering system.  The CG stands for General Electric contractor.  Some CG- tubes were listed, but not that one.  I think this is the first time that Lud's book didn't have some description of a rare tube I was looking up.  Lud did a fantastic job however, in his research and listings.

[k7mdo]

Thanks for checking!  Well, someone may have a clue.... it is a triode with huge graphite plate and the grid connection sticking out the bottom...  it is about 16" or more tall and 7-8 inches in diameter...  (filament checks good!)

I did retrieve a very well built 4-400's amplifier and power supply.... 6LF6 drivers and a single tube in front of them that I haven't identified yet....  it looks complete but until I get the case off of it and the power supply who knows....  the two 4-400 plate caps are missing but I think I have some in my junk drawer....

This fellow was an incredible hoarder and I spent a lot of time going through his buildings.  Someone had been there before though and the "obvious" high dollar stuff was missing.

Good thing my wife didn't get wind of this accretion.....  she is always after me to "clean" up the ham shack! 

Tom

[K4QE]

Is this it?

https://frank.pocnet.net/sheets/141/g/GL851.pdf

[k7mdo]

Yes, it looks very close if it isnt!

I'll post a photo tomorrow. 

73, Tom

[WB6NVH]

851 was a 1.5 KW PA tube used in a couple of naval transmitters below 3 MHz.  Can't recall which ones off the top of my head.

[K4QE]

The Navy TAB type transmitters used them.

http://navy-radio.com/manuals/94200/94200.1a_9-2.pdf

[Tom WA3KLR]

One interesting thing to me about the 851 is that the filament connections are at the top and the plate at the bottom (when used vertically).

[k7mdo]

I promised a picture of the tube and so: attached.  I set a 4-1000 and a 4-400 flanking it....

I did not note that the filament pins were on the top, unless I don't know which way is up!

The two round pins on the bottom show continuity as though filament.

Tom

[Tom WA3KLR]

For some reason, they want the larger filament base end at the top when the tube is run vertical.  This is noted at the bottom of page 1 of the data sheet under Mounting. Also, the pictorial of the tube of page 4 shows the vertical orientation with the anode base at the bottom, backwards from what we are used to, that's why I mentioned it. The dimensions should match your tube also.