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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I posted the following message today on the Flex site. I
thought it might be of interest to the HPSDR folks. It certainly is an
interesting little amp, and might find its way into the projects over here. Let
me know if you find it helpful.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>Recently I built a couple of
wide-band common-base transformer feedback (CBTF) amplifiers as described by
Dallas Lankford in this article :</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>[<<u><font color=blue><span
style='color:blue'><a
href="http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%25">http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%</a></span></font></u></span></font></p>
<p class=MsoNormal style='text-autospace:none'><span class=MsoHyperlink><u><font
size=2 color=blue face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New"'><a
href="http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%25">20Amplifiers.pdf#search=%22dallas%20lankford%20CBTF%22>]</a></span></font></u></span></p>
<p class=MsoNormal><span class=MsoHyperlink><u><font size=2 color=blue
face=Arial><span style='font-size:10.0pt;font-family:Arial'><a
href="http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%25"><span
style='text-decoration:none'> </span></a></span></font></u></span></p>
<p class=MsoNormal><span class=MsoHyperlink><u><font size=2 color=blue
face=Arial><span style='font-size:10.0pt;font-family:Arial'><a
href="http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%25"><span
style='text-decoration:none'> </span></a></span></font></u></span></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>I built the push-pull
version with 2N3053's in the 1 :11 :4 ratio which gave me 16 db gain across the
HF bands, and used it as a rf preamplifier ahead of the SDR-1000, just to see
how well it would work. I haven't exhaustively tested it yet, but my early
impression is that it improves small signal reception quite a lot, especially
when trying to separate low level signals very close to higher power
interference. The IP2 and IP3 specs on this amplifier are pretty awesome. In
almost all cases, signal readability is improved significantly.</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>So I thought that I'd pass
along the suggestion to those who like to experiment with this kind of thing.
The amp is cheap and dead easy to build and a lot of fun to play with. I'm
building another now for lofer work, and</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>I even use one as a
preamplifier for my oscilloscope! I'm not suggesting</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>that the SDR-1000 needs this
kind of amp, but at my QTH and with my antenna, the improvement is certainly noticeable,
very welcome, and it seems to benefit all modes of operation. </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>Even if you don't want to
build the amp, the article is well worth reading.</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>Just don't flame me for
actually suggesting that our SDR needs more hardware!</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>Thanks,</span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>Ken WR5H</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
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