At 08:08 AM 4/15/97 -0400, you wrote:
>>I put my resistors in the primary..this serves as a soft-start also,
limiting
>>the initial surge current on the filament of the 8877.
>
>Eimac says nothing about a requirement to limit inrush-current to the
>8877's heater.
>
If you have 6 volts measured at the tube pins, you obviously need a
resistor in
the circuit. Primary or secondary; builder's choice. It is not put there
for the
primary purpose of inrush current limiting; this is an added bonus.
Eimac assumes that the filament transformer design is matched to the
tube's filament
power requirements. This is not always the case, i.e. a homebrew amp with a
20-30 amp
filament transformer from the junk box. In the Alpha 77DX, the later models
have
a 20 amp filament winding instead of 10 amps. I have measured two 77's here at
5.92 and 5.88 volts at the pins. The limiting action of the resistor certainly
cannot hurt anything! If a surge is available upon turn-on, it is
dissipated in
the resistor. If not, the resistor goes about its business of holding the
voltage
at the proper value.
(((73)))
Phil, K5PC
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