Re: [IC-7000] Re: "tune" position


thanks steve , I bow to your greater wisdom on the subject and its handy
to know if your ever stuck and need a quick and dirty solution to the
tuning issue out bush somewhere.

tnx again

On 3/05/2013 18:55, Steve W3AHL wrote:

The circuit referenced on KC2WI's web page does NOT affect the
temperature sensor and fan control.

What does cause a problem is applying a voltage greater than 3.3 VDC
to TUNER pin 1 by connecting it to TUNER pin 2 or some other signal
that uses a TTL (5 VDC) logic level. This causes the 7K's 3.3 volt bus
that supplies CPU pin 112 (VREF) to be driven higher than 3.3 volts
through D1304 on the Logic board (a dual clamping diode). This higher
supply voltage affects the CPU A/D converter reference voltage,
causing the temperature sensor calibration to be incorrect.

There are some tuner circuits and DIY circuits that have this problem.

Steve, W3AHL

--- In <>,
jacqui <vk5kfm@...> wrote:

before you run out and buy the handful of parts of this project be
advised it will likely interfere with the fan control on the IC7000 and
may lead to you killing the radio due to heat issues.
the tuner must be an open collector system to avoid the fan cct issue
this has been discussed before here. this cct on the link below works
fine for the IC706 and other radios but NOT the ic7000

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