If it were me, I'd use the I2C bus. In the freq change routine, figure out what band it's in and send that info on the bus to a PCF8574 (for 8 bands, PCF8575 for 16) to switch the relay(s). The 8574 or 8575 would be on the amplifier. Use shielded cable and interference shouldn't be an issue.
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On 01/20/2018 09:11 AM, Gordon Gibby wrote:
If you wanted to use an arduino nano to do automated bandswitching of
the low pass filters in a WA2EBY type amplifier (and possibly also
automated attenuator input pad adjustment),
what would be the best way to gauge/measure the input band?
1. some sort of frequency counter? maybe some already built thing
2. some sort of system developing two analog voltages, one related to
peak input voltage and the other through a low- or high-pass filter
giving a different analog voltage based on input frquency, divide the
two to figure out what band is in use?
3. maybe some output from the ubitx (if you're using a ubitx)?
Any suggestions from the gurus here? It would really be nice to have
automated bandswitching on this sort of amplifier.