Al,
What are you using to determine the 3 volts? The Band Data output lines
are pulled up to 5 volts by a 2.2 kohm resistor. If the device you are
measuring with has a load of 3.3k, the voltage measured would be 3 volts.
BTW - the switching level for TTL (or CMOS) is +1.5 volts, so 3 volts
will be interpreted as a high level with no problem (and plenty of noise
margin).
Typically the low level is the one that causes problems - check to be
certain the voltage for the non-active band data lines is 0.5 volt or less.
73,
Don W3FPR
Alfred Frugoli wrote:
> Hello,
>
> I'm working on wiring up a band decoder to the ACC port on the back of the
> K3. I'm seeing 3V when a BCD pin is active. The rig is SN 4094. The
> manual says that "older" rigs may need a pull up resistor. I wouldn't have
> thought that a brand new out of the warehouse rig would have been an "older"
> K3. Am I missing something?
>
> Thanks.
>
> 73 de Al, KE1FO
>
>
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