[RTTY] Bright Idea #99

[radioman]

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 at mac.com>
To: "RTTY GROUP" <rtty at 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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