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Re: [TCML] 715B VTTC



Make that an early 1940's tube. Not sure when the B came out but I used to have a very ancient WW2 radar transmitter using one for the modulator. One thing I've always been intrigued by but without the ambition to try is use one of those HV pulse tubes in a grid blocking oscillator. No modulator necessary, just right values of grid capacitance and resistance. Rectify an NST and use it for the plate supply. A lot of the early VHF radar transmitters used tubes like the VT127 or equivalent under exactly the same conditions and got power outputs of as much as 100 kW.

Ed

David Sharpe wrote:

Vladi

Tube is a 1950-60's vintage radar pulse modulator tube capable of 17A
at 17kV maximum input.
Can also be used as a gated high power oscillator (very short duty
cycle <<5%).  Non-standard
filament voltage (26V, 2A)

http://www.radiomuseum.org/tubes/tube_715a.html

http://zugzwanged.org/dat/bin/electronics/120_White_RSI_63_3156_1992_Hi_Pwr_Microwave_Pulse_Gen.pdf

The above reference actually shows tube in its intended use
with circuit parameters.

Tube characteristic curves are at:

http://scottbecker.net/tube/sheets/061/p/P535-1E.pdf

PRECAUTIONS:
1.  Tube filaments are oxide coated (to achieve high cathode current capacity)
    and require a minimum of 1 minute warm up prior to use, longer heating
    time is necessary to achieve "gettering" effect on vacuum if operating tube
    close to its maximum ratings (15kV, 3 minutes per above "P353-1E"
reference).
    If HV is applied sooner, cathode coating can be stripped off
filaments, leading
    to anode current reduction and eventual failure.

2.  X-Rays:  At voltages tube is capable of operating, soft X-rays can
and probably
    will be generated.  Tube, socket, and oscillator support hardware should be
    installed in metal enclosure with feed-through insulators sized
for applied voltage.

3.  HV KILLS.  The pulse power capability of this tube is sufficient
to be hazardous!

4.  Cooling- recommend force air cooling to prolong tube life.  Note
well the tubes
    continuous CW anode dissipation is only 60W.

I have 5 NOS versions of this tube with 4 ceramic latch down sockets, hope to
eventually build a pulse modulator type VTTC using two of these tubes in
push-pull.

Regards



On Thu, Sep 23, 2010 at 9:18 AM, Vladimiro Mazzilli <V.Mazzilli@xxxxxxx> wrote:
Hi all
I have found this old topic looking for James 3xc3000 big tubecoil. I have several pieces of 715A 715B 715C and Russian equivalent GMI83 and GMI83V and I'm working on a single tube VTTC, for the moment the coil reaches 12" spark with a little mot not doubled at 75% rated input voltage.
Plate seems to keep grey colour.

Vladi



Vladimiro Mazzilli
Ricerca & Sviluppo
Aros
Via Somalia 20
20032 Cormano (MI)
Tel. +39 02 66327266 - Fax. +39 02 66327528
Skype Id:  - VoIp:
E-mail: V.Mazzilli@xxxxxxx
Web: http://www.aros.it
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Da: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] Per conto di sparktron01@xxxxxxxxxxx
Inviato: martedì 17 febbraio 2009 0.36
A: Tesla List
Oggetto: [TCML] 715B VTTC

All

Someone posted a while back about building a VTTC using 715B
Radar modulator tubes. Please contact me off list to discuss further.

Thanks

Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA, USA
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