> > measures writes ...
> >
> > ? A rheostat to adj. fil/heater potential costs under five dollars
> > wholesale. Do any MFJ-Ameritron amps have one? Would people pay a bit
> > extra for such a feature?
> >
>
> To be effective the filament rheostat would require built-in metering with
> proper RF decoupling at considerably more cost or would encourage
> semi-trained appliance operators to operate their amplifiers in a very
> unsafe manner (covers off, power on) in order to set the filament voltage
> properly.
Hi Joe,
Right you are, but you left off the cost of a separate transformer
that has only filament functions.
What Rich left off was that all of the amplifiers have multiple
filament taps that allow adjustment for high and low line voltages.
Not only that, tube failure from low emission are almost unheard of
in amateur service, because of the low filament hours. The bulk of
failures are seal failures, internal tube defects (like poor welds), and
dissipation failures.
Adding $50-100 in cost to everyone just so one out of a thousand
people feel more secure is a silly idea, especially when most
modern hams can barely tune an amplifier!
73, Tom W8JI
w8ji@contesting.com
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