[Amps] Checking Filament Voltage

[MU 4CX250B]

The simplest solution for amps with separate filament xfmrs is
probably to install an inrush current limiter in series with the
xfmr's primary winding. These look like disc capacitors and cost about
a dollar. I use them frequently on any circuit that has a initial
surge current, and a constant load current in equilibrium.

Probably the easiest amplifier to install one in is the drake L4B. I
removed the jumper on a terminal strip and replaced it with the
current limiter. Took five minutes, most of which was spent removing
the screws on the bottom cover.
73,
Jim w8zr


Sent from my iPhone

> On Feb 21, 2017, at 12:08 PM, Bill Turner <dezrat at outlook.com> wrote:
>
> ------------ ORIGINAL MESSAGE ------------(may be snipped)
>
>> On Tue, 21 Feb 2017 12:29:06 -0500, Ron wrote:
>>
>>  I believe in this situation a huge rheostat would be better than a
>> variable transformer of any kind.  The rheostat would greatly reduce
>> the "in-rush surge current."  This will be much kinder to the filament
>> of the tube/s.
>
> REPLY:
>
> IMO, if inrush current is a concern, one should install a step-start
> circuit rather than depend on a rheostat which might or might not be
> sufficient.
>
> 73, Bill W6WRT
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