R2
Modifications
by
John Seboldt, K0JD,
Milwaukee,
WI |
Last update: 3/23/04
(format)
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The
Mods
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r2pamp.txt,
a lower-noise
audio preamp and revised diplexer design by Glen Leinweber, VE3DNL
Glen's
complete
R2a. I have actually built (and regularly use) the revised
audio phase shift network from Glen's article, one which includes
trimpots
to really get the phasing right on over a band of audio frequencies.
It's
also optimized for lower noise. Using his suggestion to wind your own
audio
inductors on potcores, I've also made a three-pole LC highpass filter
at
about 600 Hz, for tighter CW response. It's switchable back to a
single-pole
highpass at 300 Hz for voice and casual CW reception.
The
SETI League,
Inc. Hydrogen Line Receiver Development Photos - this is none other
than an R2 receiver, modified for a full 22 kHz audio bandpass. Good
for
sweeping space for alien intelligence - AND would meet all my wildest
hi-fi
specs! Kanga even sells a kit version with these mods.
W1AAZ's 850 Hz CW filter - the link has
disappeared,
I'll
check my rig
and post details later
A
few
of
my mods
to the basic circuit -- quick and dirty tighter bandpass, faster
recovery
for QSK, a cure for excess popping with keying at high gain.
R2-DSP,
the
online version of the recent QST article on a DSP for the R2, by Rob
Frohne,
KL7NA/W7. (Funny: the ham station is all haywired analog, but the very
computer I'm using contains a Motorola DSP of the same
family as used
in
the article. It's on my Soundscape Mixtreme professional audio card! Oh
well, someday we'll get that ham station digitized...)
The QRP2000 project by
G0BBL - something like what I'm aspiring toward, with full DDS
generation of both I and Q LO signals and complete microprocessor
control.
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