Re: CETRON 810, and John's small coil.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 11/1/01 9:18:24 PM Eastern Standard Time, tesla-at-pupman-dot-com 
writes:

> Well John, 
>  
>          On that note, perhaps I should just avoid the 811-A's all 
together. 
> My
>  friend Brian is on the hunt for some 833's for me. Also, when he was 
calling
>  around he found out that the CETRON 810 that he sold to $10.00 actually 
> could
>  have been sold for much more (Supposedly, $380.00 new from his supplier!!) 

Hi,

I've seen HF-300's for $450, so tubes can be expensive.   Yeah, I'd
forget about the 811A's.

> He tells me that I might want to buy the rest
>  of the RCA 5-125B's while they have them in stock, because that is all they
>  have, and more than likely all they are ever going to get. 

I get the impression from my tube manual that the 5-125B is not so
great.  Kind of a small tube overall.  Good for a small coil I guess.
It's best to avoid tetrodes.... too much trouble bothering with
screen grids, etc. at least IMO.  They tend to be less robust also.

>  
>  Also John, do you know where I can find a schematic of the small (single 
810)
> coil that you described? 

The schematic at my website which uses (2) 833A's can be used,
but use the single 810 tube instead.  That coil uses staccato, but
you don't have to use that aspect.  It may require a different grid leak
resistance, otherwise it should work fine.  I've used many different
tubes in that coil, including ones that were very much like the 810.
I like this coil design because the secondary is only 3" x 12" but
it can give up to 24" tube coil sparks.  Maybe longer.... I've
never tried.
>  
>  Hum? Even though the 5-125A is harder to work with, do you think I would be
>  smart to snatch up the four 5-125's for $40.00? He has them saved back for 
> me.

Well it depends on if you plan on building some smaller coils, or want it
for the novelty, or to sell them, etc.

>  He also has some new, HUGE, rectifier tubes (GL 6807GE) that he will also 
> give
>  to me for $10.00. Then there is the one NL-635 by National Power Tube for
>  $5.00. All of the tubes are new in the box. By the way, if you are 
> interested
>  in any of these just let me know and I will get them for you at my cost. 

Thanks, but I have enough tubes.  I tend not to use tube rectifiers,
but use solid state rectifiers instead, when I do use them.

> Heck,
>  I don't even know how to use them, so they are useless to me. Anyhow, 
thanks
>  everyone. I will keep my eyes open for another 810's.

The trick to getting long sparks from the 810 is to run it way
over its rated voltage.  The rated voltage is 2500VDC probably,
but I run that sort of tube at 4000VAC.

Cheers,
JOhn
>