Re: Hydrogen diodes!!!??

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: Hydrogen diodes!!!??
From: Tesla List <tesla-at-stic-dot-net>
Date: Tue, 9 Sep 1997 18:54:59 -0500
Approved: tesla-at-stic-dot-net

From: 	richard hull[SMTP:rhull-at-richmond.infi-dot-net]
Sent: 	Tuesday, September 09, 1997 1:28 PM
To: 	Tesla List
Subject: 	Re: Hydrogen diodes!!!??

At 09:32 AM 9/7/97 -0500, you wrote:
>
>From: 	Richard Wayne Wall[SMTP:rwall-at-ix-dot-netcom-dot-com]
>Sent: 	Saturday, September 06, 1997 3:28 PM
>To: 	Tesla List
>Subject: 	Re: Hydrogen diodes!!!??
>
>RH wrote: 
>
>>Well during the long trip to NY, Kim, Dave and I mulled over the issue 
>>of back to back timed H2 thyratrons.  I advanced that a simple mercury 
>>vapor diode (866) in reverse would at least allow for one reversal in 
>>the primary circuit.  All of us thought that a capital idea.
>>
>>On returning and consulting the data sheets, I was dismayed to find 
>>that the standard Hg vapor diode needs a horrendous 8-10usec to fully 
>>ionize!!! (~1000usec to click off)  Unfortunately, it's all over but 
>>th' shoutin' by the time the darned merc gets goin'.
>
>Richard it's simple enough to give it a quick go.  Don't be put off by 
>just a few specs.  Sometimes new discoveries are made when they're 
>least expected.  The delay will probably change the harmonic content of 
>the waveform.  It could be beneficial.  Who knows until it's tried?  
>Since 866As have a max PIV of ~10 kV, you will probably need a couple 
>in series.............................


The conduction in mercury to any real current demands full ionization.  I
checked and the max pulse current to these, when on, is a barely usable 50
amps.  The off time is too long also, and the cathode material will be
ripped off and cast into the tube in flames.  I have done this one back in
1966 in industrial electronics when reversing a motor controller too fast.
This is also the reason these merc toobz are limited to under 500hz action
in real power situations.  Below 500hz, few silicon units can match their
robust nature...................

>
>>Hydrogen diodes (100nsec click on time) are available, but are about 
>>1000 times rarer (surplus) than the average H2 thyratron!  
>
>But, they are out there, if you look for them.  I just picked up two 
>1B45s very cheap at SkyCraft.  They are Argon-Hydrogen spark gap 
>diodes.  They conduct at 2.7 kV and 450 A.  All these vacuum tube 
>diodes begin with 1B.  (See "Tube Lore").................
 


These 1B45's are indeed spark gaps and not true rectifiers and will conduct
both ways, in both arc and glow mode!  Used as crude TR switches in slow
pulse systems and over voltage guards in radar.  Can only fire very
intermittently to rated power.  Bad news for what I
need............................
>
>snip
>
>> Lots more to this than meets the first blush conceptualization.  
>>Still, I will endeavor to vary the effective primary circuit on time 
>>electronically.
>
>I concur.  Currently, I am trying to directly base drive a resonator.  
>I am trying to totally eliminate the primary and secondary of the 
>driver.  The driver is a direct current vacuum tube driver.  The trick 
>is to switch the base to ground circuit off, fire the driving pulse, 
>then immediately switch the base ground circuit back on.  As you can 
>imagine, timing is critical, as well as, rise time, frequency and 
>harmonic content of the driving pulse.
>
>RWW

I look forward to discussing this matter with you in a few days.

Richard
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