My personal experience is de-rating the heaters to about 90% and
putting a mini fan.. can double or triple the life of these old valve
baseed equipment.. Putting a series resistor with the heater puts out
the same amount of heat in the system... But I will defer to your
expertise...
Cheers
AG
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On 9/18/2011 11:36 AM, martin562284 wrote:
--- In LTspice@... <mailto:LTspice%40yahoogroups.com>,
Ganesan <dg1@...> wrote:
My question is, Whether the plate current to heater coupling is
correctly modeled through an rms function ?
Cheers
AG
AG,
non of the valve (tube) models I've come across (and I've seen quite a
few) model the effect of varying heater current or voltage - they
simply (attempt) to model the relationship between the electrode
voltages and currents. In effect they assume that the heater is
working at nominal voltage/current from time zero. If I need to modal
the heater current draw when working on power supply designs I usually
just use a resistor or current sink.
If you are interested in the heater transient behaviour at switch
on/off, the guy who runs the DuncanAmps site (www.duncanamps.com) has
done some work on this, I believe. You could also take a look at our
own Helmut's and analog spiceman's excellent work on filament lamps in
the Files section of this group.
Please note that running heaters at anything other than nominal
voltage current is not recommended. Over OR under can shorten their life.
Do be aware that most, if not all, of the models are reasonably
accurate only over a limited range. Operation outside of or even near
the extremes of the characteristic curves published on the datasheets
should not necessarily be considered as real-world behaviour.
Martin
My personal experience
