[NLRS] 2M FM rig question

[Dr. Gerald N. Johnson, electrical engineer]

None of the VHF mobile FM rigs include HF receive. Only the multiband
multi modes e.g. the FT100D and IC706 give reception from DC to 500+ MHz
plus ham band transmit. HF reception in my VX5R is rotten until I add an
external antenna wire. Then it lacks selectivity.

I'm liking my Kenwood TM-261. Receiving airport weather and NOAA weather
is handy, and its not expensive. Kenwood microphones tend to fail when
the rubber internal button between the PTT lever and the PTT switch gets
too soft. The most popular cure is a 4-40 x 1/4 self tapping screw in
place of the orange internal button. One other cure is to saturate the
foam with crazy glue. Its important to set the screw length so it just
actuates the PTT switch. too long could break the switch loose from the
PC board.

A simple converter using an NE602 with a 118 to 170 MHz overtone crystal
(or a 1/2 some frequency) switched to the input would upconvert for the
TM-261 in AM mode. Needs only a low pass filter on its input (might be
better to be a SBL-1 for better dynamic range). 118 to 174 MHz tunable
IF could give DC to 56 MHz AM/FM receive... Selectivity at HF would be a
little poor, probably 15 to 20 KHz using the FM filter. Hm. Seems like a
friendly project for SW listening while traveling.

73, Jerry, K0CQ
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.