Re: pretty good vttc tube

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

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

>  I wanted to tell of a pretty good vttc tube for the beginners.
> It is a VT-127A triode that i got from a vender in arizona. The vendor
> was just commented on a week or so ago by a list member, and maybe the
> list member that recommended them will post the name and address again?
> (i lost it)
> They said that they had quite a few of them on hand, the cost to me was
> $7.00 each before shipping.
> 
> http://hereford.ampr-dot-org/cgi-bin/tube?tube=VT-127A
> 
>  These tubes are nice for beginners (as i was am at this time) because
> the two filament electrodes are on the bottom, the grid electrodes are
> sticking out the sides and are doubled up so there is two grid
> electrodes for the one grid. These exit the side of the oddly
> cylindrical tube opposite each other, the plate electrodes are above the
> grid electrodes and are sticking out the sides exactly the same way.
> The reason these are nice is that it makes connecting leads very easy
> without confusion and they can even be tried with alligator clip
> "cheaters" to get them running (i know because that's how i do it).
>  The filament uses 5v-at-10amp, the maximum plate is 3000v (good for mot's
> in plate tranny), power out is around 400w per tube. +
> I used two of these and i used david trimmels mot vttc design "to the
> letter" meaning i matched cap specs, resistor specs and primary turns,
> grid turns, ect. ect.. The only thing different was that i used one of
> my "test" secondary.
>  It gave nice 4" output the TIME OUT!?, with some tuning and "dinging"
> around i managed 6"-7" discharge (it even impressed my girlfriend! a
> real hard feat, but she likes to hold a neon tube and have it light) 

	Please post the vendor here.  As for the VT-127A, 227A and 327A they
were commonly run with 10 kV DC or more on the plates in self-pulsing
"blocking oscillator" VHF radar transmitters, where outputs of the order
of 50 kW were achieved.  I have been hoping someone would try them with
a power supply using the rectified output of an NST.  I suspect that the
peak power would be high enough to result in behavior more like that
obtained with a spark gap circuit.

	Information on this type of transmitter is probably available in a lot
of places, but good examples are given in the old training publication
"RADAR SYSTEM FUNDAMENTALS", NAVSHIPS 900,917.  The original publication
date was 1944, but I syspect there are a lot of them around.

	Please try it someone!

Ed