Re: Filament voltages

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

Original poster: "marc metlicka by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>



Tesla list wrote:
> 
> Original poster: "sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<sundog-at-timeship-dot-net>
> 
> Hi Dave,
> 
>     The tranny for the Quad 833 is a separate tranny than the plate
> tranny.  It's wound with 1/8" tubing on an old NST core.  Unloaded I get
> 10.2v on it, loaded that drops to around 7v (pushing 4 tubes).  Do I need
> to correct the fully-heated filament voltage to 10v, or let it sit at 7v?
> 
> Shad
> 
> 
Shad,
 Yes,
 You should read 10v-at-10Amp after the fil. comes up to temp! then read
fil. current and voltage after plate power is applied. If both plate
current on load (vttc output) and fil. V and I drop, then a stronger
core transformer with heavy windings is needed!
 you want both the plate tranny and the fil. tranny to stabilize at the
working specs of the tube "AFTER" full output is had.
This is how i got the impressive output from the 127-A's.
Of coarse over powering is fun too!
Marc M.