Use for a WE 715B tube?

[K4TLJ]

A friend gave me a WE 715B pulse modulator tube that he had in his basement for 50 years. The tube was developed for WW2 radar. His next door neighbor was a Ham in the fifties and gave the tube to my friend as a souvenir. I found info re the 715C which appears almost identical here. http://www.mif.pg.gda.pl/homepages/frank/sheets/049/7/715C.pdf

Has anyone found a good use for this tube in amateur radio? NOS are fairly expensive from a bit of Google searching. It has a plate dissipation of 60 watts with 225 watts input continuous duty but can pass 225000 watts (15 amps at 15KV) in microsecond pulses! There are no curves for reduced plate voltage (say 1500 volts). The tube has four cathodes in parallel so can pass a LOT of current even at lower voltages. Looks like a fun tube to experiment with.

[WBear2GCR]

Sounds like you want to make a PDM rig with it?

 

         _-_-bear

[K4TLJ]

Sounds like you want to make a PDM rig with it?

 

         _-_-bear

Not really. I thought that since the tube came from a Ham fifty years ago that he probably had a use for it. My friend said the Ham had a case of them obtained war surplus and was building 'something' using the 715s. Just wanting to know what that 'something' was...

I have the tube on display in my collection and would not molest it unless lots more could be found cheaply.

[W3RSW]

Run a load line through one of those charts and you'll see it's a pretty strapping tube on the order of maybe 1 1/2 to twice a 211 or VT4C in some respects but somewhat less continuous plate dissapation and other ratings in other respects, but, hey, it's a tetrode with a plate cap.  - Gorgeous.

VT4C fil. wattage @32.5, (10 x 3.25)
715C       65watts,         (26 x 2.5)

P_D VT4 @ 60 to 100 watts depending on service, A to C
                  715C      60 watts.

I just compared it with the VT4 because the base and socket looks similar. Also the bulb's about the same diameter but shorter than te VT4.
Lash up that baby and try it out in a CW rig.

[KM1H]

That tube received several writeups in the 50-60's era as they were everywhere at giveaway prices. Oddball socket if I remember.

Its not a SSB tube but in GG it made a decent CW amp at 1kV. Dont remember any AM specific applications but it was reported squirrely above 20M in Class C grid driven. CQ I believe had most of the articles.

Carl
KM1H

[K4TLJ]

That tube received several writeups in the 50-60's era as they were everywhere at giveaway prices. Oddball socket if I remember.

Its not a SSB tube but in GG it made a decent CW amp at 1kV. Dont remember any AM specific applications but it was reported squirrely above 20M in Class C grid driven. CQ I believe had most of the articles.

Carl
KM1H

I just tried a search of the ARRL archives and came up with one article from a 1961 QST and one from 1959.

Appears my hunch re 1500 volts plate was close. Apparently there were lots of these tubes at one time. My friend was a fire control technician in the Navy just after WW2. He says that he was required to destroy all used 715 tubes and dump the remains in the sea for security reasons.

[John K5PRO]

Find a copy of the MIT Rad Lab series from WWII, volume 5, chapter 3, Vacuum Tubes as Switches. The 715B is pictured along with characteristic curves, it was a hard tube modulator tetrode for early US radar. Developed by Bell Labs, it could pulse 150 kW in microsecond pulses, with 1.5 kV drop across the tube (fully on) having 15 amps of plate current, and the grid at +200 VDC to pulse it on. It was used to replace a pair of 304THs that were used similarly. Not a real linear tube, it was quite a feat at the time. I have a copy of the chapter as a 1.6 MB PDF if you want it.

[K4TLJ]

I would like a copy. My email is good in QRZ.