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Philco 90 No Spkr or Output Transf.
#6

In further thinking about this problem I realized two main
things that I had overlooked:

1. My simulator was set for an initial phase angle of 0
for the sine wave from the wall socket. Obviously this
is the best case scenario. I changed it to 90 degrees
which should be the worst case scenario and the
peak first cycle current went up to 1.4 amps!

2. However, I think this is all moot as in real life
the tube is cold when you first throw the power switch
so there is no way it's going to be this bad. As the tube
warms up it's conductance will improve so there is a
built-in soft start.

I suppose one could worry about somehow plugging
in an already warmed up set so you really do get full
tube conductance on the first cycle. In that case I think
I'm still almost a factor of two away from a problem.

The 32 uF max capacitance on the 80 rect probably has
more to do with the repetitive current pulses on an ongoing
basis rather than anything to do with first powerup. It then
also should matter what kind of capacitor you have and what
its equiv. series resistance is etc...

Anyone have any thoughts on this interesting problem?

Herb S.


Messages In This Thread
Philco 90 No Spkr or Output Transf. - by hsusmann - 04-16-2014, 04:01 PM
RE: Philco 90 No Spkr or Output Transf. - by hsusmann - 04-16-2014, 06:43 PM



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