> >I've just ordered 2 sets of 4 x 31LQ6 tubes for my little Dentron
> GLA-1000
> >amp. These will replace the tired 6LQ6 tubes presently in the unit.
> >
> >The tube swap will of course necessitate an extra transformer to run the
>
> >heaters of the new tubes.
> >
> >Does anybody on the reflector have an idea of the current drawn by the
> >heaters in these tubes?
> >
> >I figure that the overall heater VA ratings should be similar to the
> 6LQ6
> >heaters and so I figure on around 2A total for the four tubes in
> parallel.
> >I have a transformer rated at 100VA which I hope will do the job with a
> >generous safety margin.
> >
> >Am I correct in the above assumption?
>
> Hi Alek,
> Yes, that's the way it works -- should be right around 500 mA per
> tube. The 31's also have a "controlled" warm-up time which was a
> requirement for their original application in series filament string
> style TV's.
>
Just a note to the above remark on controlled warm up time---
Remember to put a series resistor or thermister in the primary for a soft
start.
Sweep tubes designed for "Series String Filaments" i.e 31LQ6 not like to get
hit hard at turn-on.
Another way is to series connect the filaments and add a suitable series
resistor. If you have low line voltage this may be a problem requiring
series parallel connection with the resistor. All three ways will work fine
in this application.
Keep in mind that many of the TV sweep tubes may not be quite as tough as
the OEM tubes, so you may want to back off a bit on the amp's published
specs.
........Merit, W6NQ
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