Not to be a kill joy..
but I believe there are other lists for this..
(yes I am mad cause a AMP fell on my contesting fun)
hehehe..
Tony
----- Original Message -----
From: "Kok Chen" <chen@mac.com>
To: "RTTY GROUP" <rtty@contesting.com>
Sent: Sunday, December 19, 2004 7:24 PM
Subject: Re: [RTTY] Bright Idea #99
> On Dec 19, 2004, at 3:43 PM, Jerry Flanders wrote:
> > A few years ago QST ran an article on a class "E" amp (might have been
> > "D"). VERY efficient - better than 90%, I think (so cooling problems
> > are minimized). A "switcher" at the operating freq, as I recall.
>
> There have been a few articles on Class E amps in the past couple of
> years of QEX, mostly from a Caltech bunch (bachelors and masters
> theses), and one or two of them have been watered down for QST
> consumption.
>
> The operating principle is not like the Class D (basically pwm, I
> think); Class E instead turns the transistor on right at the point the
> tank circuit has swung the voltage across the source/drain to zero,
> thus dissipating very little power in the transistor itself.
>
> But take a look at the amount of current flowing through some of the
> capacitors -- in one case they had to parallel a whole bunch of caps
> together because a single one would run so hot it melted the solder the
> surface mounted cap itself was mounted to the circuit board with :-).
> And they seem to need a keyed power supply in conjunction with the
> input CW, which might be easier on RTTY using a PTT relay. But I
> suspect you may need to drive the amp with FSK that is phase continuous
> as it switches between mark and space; you might lose some efficiency
> during the mark/space keying otherwise.
>
> The good news is that QEX is available in pdf form on CD-ROM and you
> can find the index to past articles at the ARRL web site.
>
> 73
> Chen, W7AY
>
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