[AMRadio] Class E Transmitter Kit

[Steve Cloutier, 978-597-3311]

Hi!

Another Amateur - Bob, K1KBW and myself (Steve, WA1QIX0 are developing a 
class E transmitter kit.

The proposed kit will use a common modulator and power supply, and use 
seperate RF amplifiers - keeping the design simple.  RF amplifiers are 
proposed for 160, 80 and 40 meters.

The power level will be between 300 and 400 watts carrier, probably around 
350 watts [power input - efficiency is around 90%].  A single 6 MOSFET RF 
module is proposed.

I am currently running 400 watts on 160, 80 and 40 meters using this design.

For the proposed class E transmitter kit, I have developed and built a 
class H analog modulator.  It is much simpler than previous designs, and is 
easy to adjust.  I am currently using this modulator with my 400 watt class 
E RF amplifiers, and the performance, stability and reliability is excellent.

Class H is high efficiency analog mode, where the power supply voltage 
supplied to the output device(s) is adjusted to provide more voltage to the 
devices when
more output voltage is required. Class H is similar to class G, where the 
supply voltages are stepped.

This class H modulator is a simpler version of the so-called class B series 
modulator which I had previously used. In addition to being simpler than 
the previous version, the audio performance is superior. This is the 
modulator I am proposing for the class E transmitter kit.

The new modulator is *VERY* simple to adjust, and eliminates the most 
complex circuitry of the original class b series modulator. It will operate 
over a wide range of input DC voltages and is very stable.

The modulator uses a small floating driver consisting of a TL074 op amp. 
Audio input is fed to the floating op-amp in differential mode, referenced 
to ground. The
driver op-amp floats along with the modulated DC. The modulated DC appears 
across the inputs of the floating op-amp in common mode. The op-amp rejects
common mode signals, leaving only the differential input signal - the 
audio. This circuit elminiates the need for DC isolation devices such as 
transformers or
opto-couplers.

Please check out the schematic if you're interested :-)  [link at bottom of 
this message]

I am seeking feedback, comments, suggestions, etc. relating to the class E 
kit, the design, packaging - whatever.  If you have anything to say, 
feelings, thoughts, etc.  *please* let them be heard.

Something like this could be a big boost for AM.  We are doing everything 
we can to drive the price as low as possible - volume parts buys, offering 
different levels of kits [active components only, with heat sinks, with 
chassis, with power supply, etc. etc. etc.] to allow for flexibility.

The class E web site [with schematics, etc.] is at:

http://www.netway.com/~stevec/ham/classe.htm

Thanks and Regards,

Steve WA1QIX