What was the resistor value you ended up with?
Have you considered placing a resistor around the control
transistor that tuns the fan on? Use a value that keep the
fan slowly turning all the time.
Dave
WA0ZZG
----- Original Message -----
From: "David Jordan" <wa3gin@erols.com>
To: "John Hirth" <w2ki@amsat.org>
Cc: "Yaesu Reflector" <yaesu@contesting.com>
Sent: Saturday, September 02, 2000 10:06 AM
Subject: Re: [Yaesu] test - don't read
>
> Here is one for you FT-900 owners.
>
> I one hot day this summer I noticed my FT-900 was warm to the touch. The
> cooling fan wasn't coming on. After some trouble shooting I found that
> the termistor in the trigger circuit for the fan had failed.
>
> Yaesu mailed me a couple of them at no charge. Received them in a
> couple of days and installed the new thermistor. However, I didn't like
> how warm the unit had to get before the fan would come on. The
> thermistor is basically operating as a resistor to ground. As the heat
> increases the resistance drops which activates the fan on circuit. By
> placing a small quarter watt 10K variable resistor in parallel with the
> thermistor I've been able to adjust the temperature at which the fan
> will activate (from on all the time, to temp selected activation).
> After some trial and error, about 3 attempts, I've got it working the
> way I like it...keeping the rig nice and cool.
>
> Have Fun,
> dave
> WA3GIN
>
>
> --
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>
>
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