[ICOM] IC-706mkIIg with TurboTuner

[J.F. Samuels]

This problem is still driving me crazy after two years.

 

My IC-706 worked fine into the tuner.

 

My newer IC-706mkIIg has always exhibited the following weird problem:

 

On 15 or 17 meters, only, when I press the antenna tune button, 95 times out
of 100 the Power Out indicator pegs instead of one or two segments, and the
antenna will never achieve resonance - it will end in beeps and reset to
zero.  The SWR meter never shows a dip.  If I remove the TurboTuner and tune
the antenna (Tarheel 200) manually, the IC-706mkIIg works fine.

 

The other five percent of the time the meter shows normal low tuning output
and I achieve resonance.  But, if I stay on high power and modulate in SSB,
the meter "sticks" up at max, and the signal at that point is not heard or
is not modulated.  A power setting of 6 or below sometimes works, but that
is not an option.

 

I finally coupled a frequency meter to the output and found that the signal
that pegged the output meter and would not achieve resonance appeared to be
about 13 mHz.  This doesn't make much sense, either, for it should achieve
resonance at that frequency OK.

 

I took a three foot RG-8X jumper and placed RF cores and a big toroid inline
and put this between the tuner and the antenna.  It has helped, and
sometimes I can tune OK and work 17 meters, sometimes 21, but not always.
Despite trying all sorts of combinations of cable lengths, placement and RF
decoupling, I cannot improve the situation.  Sometimes it is OK until I get
close to resonance while tuning, then jumps up.

 

It almost appears that the tuner is not presenting a 50 ohm load to the
output of the ICOM, perhaps something higher, and the de-loading
causes/allows a spurious oscillation in the output of the ICOM.

 

Does anyone have any suggestions?  I have also sent this query to Bill,
N2VZ, manufacturer of the TurboTuner.

 

Stumped,

 

73, John, K2CIB (since 1952)