Class E Newbie

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Class E Newbie

Postby ND9B » Sat Dec 17, 2011 9:28 pm

I'm interested in home-brewing an AM transmitter for 160 and 75 meters. I would like carrier power in the neighborhood of 200W, but I have a spare linear amplifier so I could make do with 20W. I've heard of Class E, and I'm trying to get my head around it.

First, is low level modulation out of the question? Can modulation be accomplished by driving the amplifier with a PWM signal at the RF frequency?

Is there an existing Class E design available with boards for sale? (or maybe a complete kit?)

BTW, do AMers always specify output power by "Carrier" rather than "PEP"?

Bobby Dipole, ND9B
Last edited by ND9B on Sun Dec 18, 2011 1:47 pm, edited 1 time in total.
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Re: Class E Newbie

Postby Gilly » Sun Dec 18, 2011 7:26 am

Hi Bobby

Welcome to the Forum.....
Probably best to forget about your linear and I think I know what you mean about applying PWM at the RF frequency to the TX...forget about that for the moment too......

The system/method of Class E used by most guys is similar to the Tube technology of Plate / Screen ... high level modulation....
You have a separate modulator unit and Transmitter unit etc: etc:

Steve has kits for the PWM and all parts are easy to obtain locally in your country or from guys on this forum....

As far as quoting power.... I myself say that I run 100Watts modulated to 150% or whatever...

There are no kits for the TX....they are easy to build....this is a picture of my 80M TX in construction...

Image

This TX will give you 200 Watts carrier power and its quite easy to build if you examine it....
For some reason only part of my photo comes out ! you can right click and go save if you want......

If I were you would start by building a 80M System...antennas are not difficult for that band and the output coil is not to big either......

Also would print out the articles on Steves Web site http://www.classeradio.com/ and read a few times over the next week....after a while it will make more sense......


Others might want to comment....


Wayne

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Re: Class E Newbie

Postby kf1z » Sun Dec 18, 2011 7:48 pm

I suggest forgetting you own a linear :-)

Build the 400 watt TX on Steve's page. it's been built by many, and by some, many times 8)
tried and true.

That is, as they say, 'legal limit'.

Yes, in the US anyhow, most AMers refer to output power as carrier power.

If you really don't want that much power, you can either reduce the carrier voltage level a little or build a different RF deck
But, since it's your first go at it, I suggest sticking with the design presented.
THEN after that... start expirimenting.

Even though some people may be "used to building" etc.... if they start messing about with a working design before they've
ever tried it, they tend to run into trouble. Especially when they forget about, or don't know what things can change,
or how to go about making the change!

Cost-wise, you'll only spend a scant few dallars less on 200 watts than 400 so cost isn't the consideration at all.


Anyhow.....
I see you've got the ball rolling....

LOOK OUT BELOW!! :lol:


Bruce
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