Yes Lee, I remember the project ,
looks very well made , bit of a tom-tit over the
500 to 477 migration , will the filters
re-tune ?
I have seen 7 MHz AM
stations in the usa using eer as high
level modulation , with e/d amps , I think
most high power broadcast sw use this
system as well now ? ...mobile phones use it for
envelope shaping ...... there was a page of links on
the uk500khz group
IMD / s/n levels -35 dB maximum ? which is
not bad ....ssb .. may be IMD rises as the power
o/p decreases ?
G.
Hi Graham,
All,
I made an EER PA and
Transverter to 3.5MHz for use on 500kHz based on Jim?s first
design.
And I?m sure there are
a few others about.
First prototype of
Class D PA
https://dl.dropbox.com/u/15400416/IMGP0336.JPG
3.5MHz to 500kHz
Transverter with Phase and Envelope outputs to PA
https://dl.dropbox.com/u/15400416/IMGP0371.JPG
Switchable 50 or 200W
EER PA with automatic protection
https://dl.dropbox.com/u/15400416/IMGP0415.JPG
LPF and TX/RX
Relay
https://dl.dropbox.com/u/15400416/IMGP0414.JPG
Final
Trio
https://dl.dropbox.com/u/15400416/IMGP0385.JPG
Works a treat on all
the usual modes and is even quite respectable on SSB.
90% efficient on full
output.
Stefan?s attempt at a
switched mode envelope supply sounds interesting, and a nice way to get mid
power efficiency up.
73, Lee
M0LMH.
-----Original
Message-----
From:
[email protected] [mailto:[email protected]]
On Behalf Of Graham
Sent: 12 September 2012 17:45
To:
[email protected]
Subject: Re: LF: Fw: LOST
TRACK
Published a
design and made a working system ........ he
also eliminated the need for a
complicated drive by using complimentary out
put devices ... I don't know who else made such a
thing .... ?
PS :: I vote
for Jims design !
Sent:
Wednesday, September 12, 2012 5:31 PM
Subject: Re: LF:
Fw: LOST TRACK
>You can use a
class E/D amp in linear , with
envelope restoration , that maintains the
efficiency , s/n >imd is
about 35 dB .
To my knowledge the first
description in amateur literature of an
EER (envelope elimination and
restauration) PA (400W) was by DJ7AW in CQ-DL 4/2001.
I have the article as
pdf (in German) and can send it to anyone interested in building
such
a PA which is not an easy
task.Therefore,as far as I know, only two such PAs have been
built.
One by DJ7AW and one in South
America (Joe?).
----- Original Message -----
Sent:
Wednesday, September 12, 2012 5:17 PM
Subject: Re: LF:
Fw: LOST TRACK
Things have
moved on a bit
You can use
a class E/D amp in linear , with
envelope restoration , that maintains the
efficiency , s/n imd is
about 35 dB .
The Op structure
allows for up to 50% loss of signal
randomly along the time line , ie first 50% ,
last 50% or randomly distributed
Problem with short
burst is the 'average energy' level , like a radar ,
huge KW peak powers but only watts average power
.....and yes , wide bandwidth .
Detecting a
carrier is one thing .. to recover data is a
much more difficult thing and requires a higher level
of energy
Virendatenbank: 2437/5264 -
Ausgabedatum: 12.09.2012
