[ETO_Alpha] Plate voltage HIGH

Fri, 8 Feb 2002 07:41:20 -0500

Jerry, et. al.:
    Commander is reducing the heater voltage on their 3CX800A7 amplifiers to
just under 12 volts!  They have found high grid current when the heater
voltage is at the top end of the published rating.  They usually had 13.5 -
13.8 vac on a 13.5 +/- specification.   I saw a friend's amp that was having
loading problems totally straighten out, and is now running 20 - 40 ma grid
current and +/- 30 watts drive at 1500 watts output!!!  All this with a
series resistor of 0.75 or 1 ohm (25 watt)  resistor in series with the
heater winding!
    So... I wouldn't worry about low cathode emmissions with heater voltage
going down.  Makes me think they should design at 12.6 volts instead of 13.5
(?)
    Good luck,    73
George        K8GG

----- Original Message -----
From: "Jerry" <[email protected]>
To: <[email protected]>
Sent: Tuesday, February 05, 2002 9:17 PM
Subject: [ETO_Alpha] Plate voltage HIGH


> This is strange. I have a buck boost transformer that can be set to 226 or
> 242 Volts.  ON my 89 which has the taps set for 240v, when the input
> voltage is 242, the plate voltage reads 3345 no load. I use the 226 volts
> available form the transformer I get exactly 3,000 volts.
>
> This seems unusual to me and I an concerned the filament voltage may be
too
> low.
>
> Has anyone ever seen this kind of behavior.
>
> In either voltage settings the amp makes rated power plus.
>
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