Recently I built a couple of wide-band common-base transformer feedback (CBTF) amplifiers as described by Dallas Lankford in this article : <http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053% 20Amplifiers.pdf#search=%22dallas%20lankford%20CBTF%22>
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. 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 I even use one as a preamplifier for my oscilloscope! I'm not suggesting that the SDR-1000 needs this kind of amp, but at my QTH and with my antenna, the improvement is certainly noticable, very welcome, and it seems to benefit all modes of operation. Even if you don't want to build the amp, the article is well worth reading. Just don't flame me for actually suggesting that our SDR needs more hardware! Thanks, Ken WR5H _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
