What is a jan 8745 tube what is it used for

:What is a jan 8745 tube what is it used for

hi jan stands for joint army navy it is not a brand name brand should be on tube. an 8745 is a high mu triode exactly what its used in i am not sure as i haven't seen this tube before i think its used as a vhf or uhf amplifier but i'm not sure. butch

::What is a jan 8745 tube what is it used for
:
:
:hi jan stands for joint army navy it is not a brand name brand should be on tube. an 8745 is a high mu triode exactly what its used in i am not sure as i haven't seen this tube before i think its used as a vhf or uhf amplifier but i'm not sure. butch

:::What is a jan 8745 tube what is it used for
::
::
::hi jan stands for joint army navy it is not a brand name brand should be on tube. an 8745 is a high mu triode exactly what its used in i am not sure as i haven't seen this tube before i think its used as a vh
f or uhf amplifier but i'm not sure. butch

I saw these in a sealed can on e-bay item number 6510259499 I have checked every tube book that I have and no record of that number HF Brammell

::::What is a jan 8745 tube what is it used for
:::
:::
:::hi jan stands for joint army navy it is not a brand name brand should be on tube. an 8745 is a high mu triode exactly what its used in i am not sure as i haven't seen this tube before i think its used as a vh
:f or uhf amplifier but i'm not sure. butch
:
:I saw these in a sealed can on e-bay item number 6510259499 I have checked every tube book that I have and no record of that number HF Brammell

hi this tube is in my ge essential characteristics but is not in any other tube manual i have.i looked a little farther in the base diagrams i see it is one of those ceramic and metal tubes with the round fins on one end it doesn't really look like a tube and now that i see it i think i have some of these in a box somewhere in my junk i never found a use for them they came with some military and ham stuff i got from a guy.it has a 6.0 filament which draws 1 amp 10 watts on the plate and 3500 peak volts plate.the base diagram also covers7211,7815r,7855,8403 tubes so if you have a diagram for one these you can see what it looks like. i think the ones i have came out of a fixed freq. uhf xmitter that used to belong to the faa. butch

From what I recall in my old "Boy's First Book of Radio and Electronics" by Alfred Morgan, those tubes are called "lighthouse tubes." The one I saw in the book had an octal base and a stepped shell with spaced rings. The ones in that auction do not have an octal base. The explanation for the rings, though, was some notion of keeping terminals close to the elements so that the tube could be used for ultra high frequencies--the rings were the terminals. I never did understand this, and from the looks of the tubes in the auction, the fins look almost like cooling fins.

T.D.

Hi

You can see one here:

http://www.tubecollector.org/8745.htm

Norm

:From what I recall in my old "Boy's First Book of Radio and Electronics" by Alfred Morgan, those tubes are called "lighthouse tubes." The one I saw in the book had an octal base and a stepped shell with spaced rings. The ones in that auction do not have an octal base. The explanation for the rings, though, was some notion of keeping terminals close to the elements so that the tube could be used for ultra high frequencies--the rings were the terminals. I never did understand this, and from the looks of the tubes in the auction, the fins look almost like cooling fins.
:
:T.D.

Ah! That makes sense! A close-up view! I guess those fins are really cooling fins. I couldn't see in the other picture exactly how it was constructed, but there are bands of metal separated by porcelain, so I guess those bands of metal are the contacts. I wonder why they call it a lighthouse tube! I guess it looks like a lighthouse if you set it so that it gets smaller as it goes up.

T.

:Ah! That makes sense! A close-up view! I guess those fins are really cooling fins. I couldn't see in the other picture exactly how it was constructed, but there are bands of metal separated by porcelain, so I guess those bands of metal are the contacts. I wonder why they call it a lighthouse tube! I guess it looks like a lighthouse if you set it so that it gets smaller as it goes up.
:
:T.

I operated/serviced some Bendix microwave equipment in the '60s that used these type tubes. In this equipment they plugged into cavities. I believe they were used in the rf power amp in some Federal microwave equipment of about the same era.

Radiodoc