Re: Bitx 20, Help me!
Hi,Which band are you designing it for? 4.915 is too low for 14MHz SSB and sets
the VFO tuning quite high and prone to QSY/QRH (drifting). As I have read
over there, for SSB IFs over 8MHz are better and set the VFO on lower and
more stable frequencies. Crystals between 8 and 12MHz are easy to get here
in Europe, I can get 8, 8.86, 9.83, 10, 11, 11.059 and 12 for less than 0.75
euros each, there in PA you should be also able to do so...
It is importand that measurements are done with the circuitsA way to know the filter shape is to connect a wideband noise generator or a
wobbulator to the filter input, an AM detector (diode and capacitor) to the
output and an oscilloscope (could be a PC audio oscilloscope thru the sound
card) to the AM detector. You'll see the ripple and the bell-like shape of
the filter passband. I have seen images in the net, one of them in the site
of PY2OHH, Miguel, http://geocities.yahoo.com.br/py2ohh/ It is in portuguese
but some friends are helping them to translate the pages into english...
By the way, for the ones that want to see it with an analyser: mayI am not building the BITX, but I am enjoying this list and learning about
it anyway. All the parts but the IRF510 final amplifier are easy to get here
(and I stock most of them) so it is possible I will build it someday...
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