Saturday, April 17, 2010

USB SW receiver Si570 based

...that's Uper Side Band and not Universal Serial Bus


Some time ago I started assembly of a future SW receiver based on a 10Mhz IF (there was a 10Mhz crystal promotion at the local electronics shop so I bought 10 for 1 Eur, I think). The idea was also to have some modules in a pcb for making some tests.
Since my second Si570 kit is already working I decided to use it as vfo.

Schematic is not complete (part module diagram, part schematic) but you can see them in some receiver schematics around the net:




DBM is from here: http://www.qrp.pops.net/images/2008/2008-larger/big_dbm.gif
and was made without matching the diodes (1N4148) and with diferent wire sizes in both coils...

Crystal filter and if preamplifier is from Bitx: http://www.phonestack.com/farhan/bitx.gif (see Q3 and the crystal filter) The crystals were match at no more than 80Hz difference from a reference value.

NE602 is...well...is an NE602 runing with an external oscillator.

The antenna used in this quick test was the Mini-whip with the antenna spliter (see the schematic somewere in this blog), nice signals were coming in considering there's no bandpass filter before the DBM.

Video is on 20m band with some French hams chatting. So I guess at least 1200Km range from here (didn't checked callsigns). I was also listening to Shannon volmet station and that acounts for at leat 2000Km. Not bad for some components in a PCB and a piece of cooper as antenna.


video

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