Yes, the single conversion receiver with filters at both ends of the IF
strip (or a single signal phasing detector such as KK7B's R2 or R2PRO or
R2mini http://www.bright.net/~kanga/kanga/kk7b.htm to reject opposite
side band noise) should be a delightful receiver. That's that makes the
Tentec Triton so revered. I have a couple Yaesu VHF/UHF
multiband/multimode transceivers. Their S/N after three or four
conversions and a last IF with limited head room is poor. Fatiguing to
listen to over a long period. I have an Icom IC-211 (built before they
learned how to solder a double sided board so its synthesizer stinks)
which is referenced as the epitome of bad phase noise, but being single
conversing from 2m it has a much nicer signal to noise in the receiver.
More of a pleasure to listen to.
I've just found a 2m kit from Germany
http://www.qrpproject.de/2M_ssb_cw.htm that has great dynamic range,
single conversion, VCXO for very low phase noise and crystal filters at
both ends of the IF strip. A kit without crystal filter costs 200 euro
delivered to the USA. My order is being processed. I'll build 10.738 MHz
ladder filters with Bessel response from computer crystals ordered from
Mouser. I think it would be easy to put this radio on any band below 225
MHz using the boards in the kit. I may add some sort of rate of change
noise limiter to get around its lack of noise blanker since my filters
will pass pulses as pulses and make that type of noise limiter
practical.
One of the SETI groups is proposing using a KK7B R2 with DSP for
searching for distant signals. There was an article in QST a few years
back showing that for ham use on ham bands.
73, Jerry, K0CQ
--
Entire content copyright Dr. Gerald N. Johnson. Reproduction by
permission only.
|