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Re: [TCML] 715B VTTC



IIRC about a 0.2% duty cycle - very few PPS but at humongous peak powers.

Matt


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 






-----Original Message-----
From: EVP <evp@xxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Thu, Sep 23, 2010 8:33 pm
Subject: 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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>>-----Messaggio originale----- 
>> 
>>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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> 
> 
> 
> > 
 
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