EMRFD Message Archive 10077

Message Date From Subject
10077 2014-05-30 09:24:13 shubham tiwari VU... requesting for support in constructing a 20 m/14mhz band 10 to 25 wa

Sub—requesting for support in constructing a 20 m/14mhz band 10 to 25 watts CLASS – E linear amplifier.


Hi everyone, I am working on constructing a HF linear amplifier which works on CLASS-E design, I want to use this linear with my homebrew qrp transceiver, the reason I am trying to construct a class E design is because it is very efficient >70%,I would like to use my qrp transceiver with portable car  battery so an efficient  linear is very crucial in design.

Has anyone ever used an class-e rf amplifier for 14mhz band???

Is there any design which I can utilize? I want an class – E linear amp which can cover frequency band from 14.000 to 14.300 MHz..

There is software which helps in designing such linear amplifier on this site called –http://tonnesoftware.com/

The software is known as CLASS –E,but I have no idea how to use it or what parameters does it requires..

I’ll really appreciate it ,If anyone can help me out.

Please email – vu3sxn@gmail.com








10079 2014-05-30 10:56:03 victorkoren Re: requesting for support in constructing a 20 m/14mhz band 10 to
Sorry but plain class E amplifier is not linear. It output is constant amplitude RF.
Victor - 4Z4ME
10091 2014-06-02 09:59:08 kb1gmx Re: requesting for support in constructing a 20 m/14mhz band 10 to
Without further qualification the battery size and the mode of operation are unknown.
My comments are based on some guesses as a result.

Confirm assumptions:  A  "portable car battery" is a 7AH lead type of battery?  We here sometimes 
call that a Gelled or sealed BATTERY as the electrolyte is suspended and non spillable.  It is very 
common  for portable ham use to the 10W power level and depending on duration if not long 
20 or even 30W.  However that type of battery is available in many sized from 2Ah (small) though 
in excess of 100AH (very large and heavy).

Class E is a sudgroup of switch mode amplifiers.  As a result is it NOT LINEAR.  The basic ham use
for this class is CW, or AM by DC voltage modulation, or FM.  To do SSB with it you need to do envelope reconstruction with phase correction which is both a mouthful and at lower power inefficient due to the needed electronics to do the envelope modulation.

If efficiency is needed for other than SSB class E will work for you, note that it is load sensitive so 
SWR variations will need retuning and could be a headache.

IF SSB is the intent then use a class AB1 or AB2 push pull as 45-65% efficiency is reasonable
to achieve using modest device like IRF510, better if you use RD16HHF as that is optimum for 
12 V operation

Note a 12V battery starts life freshly charged at about 13.2-13.6V and not long after is less due to the discharge characteristics so the design should work on as little as 10.5V.