[hpsdr] Envelope Elimination and Restoration on the air, phased arrays

[Robert McGwier]

In case anyone doubted our ability to do the extremely high efficiency 
amplifiers and get good linearity at the same time I refer the intrepid 
reader to this month's QEX.

Saulo Quaggio, PY2KO,  took a bunch of TV sweep tubes  (PL509) and did 
some nice work on a HV switching power supply for the "plate 
modulation".   In the end he achieved  1 KW output with IMD over 30 dB 
down with EIGHTY FIVE per cent efficiency and that was without a single 
piece of feedback in the entire system.  He tweaked it by hand.  With a 
very simple receiver sniffing the output,  and DSP feedback, we will be 
able to go further in both the approach to the hard limited amplifiers 
and we will be able to predistort and provide the necessary delays to 
get everything lined up on the final stage.

I also found N6TX's article on the mathematics of doing approximate 
computations in support of phased arrays to be interesting.  Paul is an 
AMSAT BOD member and our Education department chief executive.  I had 
hoped we could enlist his aid on any of our phased arrays (possibly L,S 
but certainly C band).  I have not given up on this yet.

Doug Smith continues to do a fantastic job with QEX. 

73's
Bob
N4HY
-- 

AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
Time for a new motto, what should I choose?