[Lowfer] IC-706

[Lyle Koehler]

I'll add a bit to what Roger, AD5T says about the IC-706 on LF. I have had
the original version of the IC-706 for a number of years, and it was my
primary receiver for BPSK, WOLF and QRSS until last fall when I bought an
IC-756PRO. A preamp and probably a filter (I use a tuned loop) is necessary
because the 706 sensitivity is pretty poor at LF. According to the ARRL
expanded test report for the IC-706 Mark IIG, the minimum detectable
sensitivity is -92 dBm at 100 kHz, -126 dBm at 500 kHz, and in the
neighborhood of -141 dBm on all of the ham bands from 160 m through 70 cm.

My original IC-706 does not have the high-stability oscillator but exhibits
negligible drift on LF, even when receiving QRSS60 signals. To use the later
versions with the thermostatically controlled cooling fan for really
narrowband stuff, it might be a good idea to bypass the thermostat so that
the fan runs continuously (or purchase the TCXO).

The original IC-706 had somewhat tinny sounding transmit audio -- very
intelligible but lacking in lows. The later models that I've heard on the
air sound just as good as most of the "big" rigs.

Kurt's comments about transmit capability down to 160 kHz are interesting. I
had heard that the IC-746 would go that low, although most ham rigs won't
transmit below 1500 kz even when "opened up". Maybe I've had a good exciter
(to be used with a 1-watt final at the antenna base) for Jason and other
modes sitting in my shack all these years.

Lyle, K0LR