Receiver single signal selectivity
Using a X-tal oscillator with 7 mV output as "clean" generator.
All measurements done at 144,114 MHz.
The YAESU FT 225 2 meter all band transceiver showing the
effect of reciprocal mixing. This reduces out of pass band
This YAESU FT 225, has been modified to have much lower
VCO sideband noise. (SM5BSZ modification). It's now possible
to se the x-tal filter response instead of just the phase
The ICOM IC 202 2 meter SSB transceiver Does not have sufficient
selectivity for serious contesting. Typical of a single x-tal
filter (6-pole?). But look at the notches of either side of the
pass band. These are only seen (measured) on stations with
low phase noise. Otherwise reciprocal mixing will "wipe them out".
The Kenwood TS 930 HF-transceiver has good selectivity, that reaches 90 dB
attenuation at +- 40 KHz from center frequency.
The FT 990 has very good attenuation outside pass band.