The only problem with pushing an 8877 or the 3CPX to or over the 4KV limit
is that it enhances the chance of instability.
Carl
KM1H
----- Original Message -----
From: "Paul Christensen" <w9ac@arrl.net>
To: <topband@contesting.com>
Sent: Wednesday, November 14, 2012 7:23 PM
Subject: Re: Topband: 8877 Tube
Bob,
A non-issue. Many of us have been running 8877s with Ep of 4KV. For
example, the typical no-load Ep of an Alpha 77Dx/Sx amp is right at the
specified limit of 4KV.
Some owners have been converting their 8877 amps over to the 3CPX1500A7
which has a much higher rated Ep since it was designed for pulsed service.
Unless someone has access to a supply of pulse-rated tubes, I think it's
waste of time unless the plate supply voltage is also increased.
Paul, W9AC
----- Original Message -----
From: "Chortek, Robert L" <Robert.Chortek@berliner.com>
To: <topband@contesting.com>
Sent: Wednesday, November 14, 2012 6:56 PM
Subject: Topband: 8877 Tube
Wonder if someone can help with a technical question with the amp I use
on 160 meters.
The Spec Sheet for the 8877 tube lists the "Absolute Maximum Plate
Voltage of 4000 Volts" for the tube, and also says in "typical operation"
the plate voltage is between 2700 and 3500 volts. In my amp (Ameritron
AL-1500), the plate voltage is 3750. My question is - should I be
concerned (it's clearly below the maximum" but above the range that is
considered "typical"? I just want to be sure I'm not adversely
affecting the useful life of the tube.
Any help would be appreciated.
73,
Bob/AA6VB
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