Perhaps these amplifier manufacturers are just trying to sell tubes, or
maybe they haven't said what they really mean:
There are several reasons why Lunar-Link Systems sells and recommends the
3CPX800A7 tubes.
1. The higher flash over voltage of the 3CPX800A7 (7000 VDC verses 5000 VDC
for the 3CX800A7) provides a substantial safety margin over tube damaging
arcs. In RF amplifier service the Peak to Peak RF voltage will approach 2
times the DC plate voltage. That is if you are running 2500 VDC plate
voltage the Peak to Peak RF voltage will be close to 5000 V or right at the
limit of what a 3CX800A7 can handle without risking a tube destroying are
across the inside of the ceramic grid to plate insulator. The 7000 volt
rating allows the 3CPX800A7 to be run at 3000 VDC plate voltage and still
have an adequate safety margin.
73,
Mike Schatzberg
WB2AJI
----- Original Message -----
From: "Roy Koeppe" <royanjoy@ncn.net>
To: "Amps Reflector" <amps@contesting.com>
Sent: Friday, April 29, 2005 5:10 PM
Subject: Re: [Amps] New Command Technologies Amp
> About:
>
> "The CPX tubes are run right up to their flashover point, of 7KV, if you
> figure RF peak volts at 2X DC anode voltage of 3.5 KV."
>
>
> That's not how it figures except for high-level a.m. plate modulation.
> In SSB and CW modes, the peak voltage on the plate is the power supply
> voltage.
>
> 73, Roy K6XK
>
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