I keep forgetting to hit reply all
----- Original Message -----
From: "Lamb" <k7fm@teleport.com>
To: "AMPS" <amps@contesting.com>
Sent: Thursday, October 26, 2000 1:05 AM
Subject: [AMPS] G2DAF Circuit
>
> Although the load would change with drive, I am not convinced that is as
big
> a problem as it might first appear. When drive is less, the output is
less.
> Buckshot usually occurs at peaks, as amplifiers flatten out. What is more
> troubling is whether the exciter is properly loaded on both half cycles at
> peak power. That is the reason for using a tuned input in the grounded
grid
> circuit. The same flywheel could be applied to the DAF circuit, as Marv
> suggested. But, we could also have rectifiers of opposite polarity
> operating into a resistor to load the negative cycle without a tuned
input.
With a tube type exciter the output tank of the exciter stage has enough Q
to prevent problems with uneven load. The tube in the driver
will still see a clean load. But with a broadband transistor exciter, like
most HF rigs use, then there's very little Q between the output transistors
and
the G2DAF input. So in the days of G2DAF, it might have worked but today,
better put in a tuned input.
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