From HPSDRwiki
Revision as of 22:46, 5 April 2009 by VK6APH (Talk | contribs)

Jump to: navigation, search


Thor is a high efficiency HF power amplifier using Envelope Elimination and Restoration (ERR) techniques.

The project leader for Thor is Dan N4XWE.

30th March 2009 - Time to kick this project back to life I think - Phil VK6APH

PC program for designing Class E amplifiers -

Possible transformer-less PWM -

More information on the above PWM -

PWM filter simulation software -

Good discussion on practical PWM filters -

1kW output 13.56MHz Class E amplifier -

10m 100w amp discussion, suitable FETs & input matching -

Corrected QST article by Sokal here -

Simple 160m Class E PA

In order to get my feet wet with Class E I built a simple 160m PA from junk box parts. The schematic is shown below. It gives 40w carrier out from a 40v supply and efficiency is in the region of 95%. The output tuning seems non-critical and has to be one of the tamest PAs I've ever built. I tried to deliberately blow it up by running it into an open and short circuit - no problems. The drain waveform was absolutely textbook.

The FET is an IRF620 (200v, 6A) I found in my junk box. Perhaps beginners luck but a good start!

160m Class E PA.JPG

Simple Pulse Width Modulator

I looks like we can make a simple PWM by connecting a couple of FETS to the Atlas bus vis:


Rather than PowerSDR sending I & Q data to Penelope we can instead send the envelope of the signal e.g. Sqrt(I^2 + Q^2) and the phase modulation e.g. arctan (Q/I). The envelope will be used to create the required PWM driver signals for the FET gates, using either the Ozy or Penelope FPGA, and the phase modulation used in the Penelope CORDIC to generate the RF drive signal for the PA.

Other Amplifiers to review

The following looks like a very interesting article and could be a suitable starting point for Thor. It describes the design of a 400w (PEP out) Class E amplifier that covers 80-15m and uses a single transistor. The article is by Josef Hisch, DJ7AW, and appeared in CQ-DL April 2001. Much of the low level RF processing could now be done in Penelope.

The article in German is here Media:400W PA.pdf

An English translation by Horst Grushow, DL6KBF, is here Media:400W PA-English.pdf

Further information on EER techniques can be found in the following publications:

Reference for all Class D, Class E and EER: RF and Microwave Power Amplifier Design, Andrei Grebnnikov, McGras Hill, 2005 ISBN 0-07-144493-9

RF Power Amplifiers for Wireless Communications, Steve Cripps, Artech House, 1999, ISBN 0-89006-989-1

Feedback Linearization of RF Power Amplifiers, Dawson & Lee, Kluwer Academic Publishers, 2004 ISBN 1-4020-8061-1

Single Sideband Systems & Circuits, Sabin & Schoenike, McGraw Hill, 1995, ISBN 0-07-912038-5

Power Supplies: Solid State Power Conversions Handbook, Tarter, Wiley Interscience, 1993, ISBN 0-471-57243-8

A very good explanation of High Efficiency Power Amplifiers can be found here -

and here -

A block diagram of Thor is shown below.


The required phase modulated RF signal and envelope(s) will be provided by the Penelope exciter.

Current design work is focused on the switching power supply and modulator.

Why Thor? Thor is the Viking god of Thunder - he was depicted as a huge man with red hair, red beard and red eyes. He was god of the sky, the ruler of storms and the deliverer of thunderbolts and rain. The Vikings believed he rode the heavens in a chariot drawn by two goats. As Thor passed overhead, thunder rumbled from the wheels of the chariot and lightning flashed from sparks created by the hooves of the goats. (He obviously designed mains connected switched mode power supplies!).