The maximum load current is programmable but can't exceed 30mA. I strongly suggest that you keep the current much lower than that and use a pull-up resistor instead of the LEDs then use the outputs to drive transistors, with suitable base resistors.
If you draw too much current or introduce spikes from the relays it will probably upset the voltage references and could even cause instability with several relays trying to operate at once, even in 'dot' mode.
If this is for receiving only, it might be possible to use the outputs directly to operate diode switches.
Brian.
The outputs of the LM3914 are 'active low', they sink current to ground to turn the LED on. If you built one input stage T1 & T2 for each loop but combined the collectors of T2 from them all to the base of a single T3 stage, then lifted R2 from ground and connected it to the LED outputs instead, it would allow the bias to be switched to one loop amplifier at a time. It might help to wire an extra resistor of say 1M from the base of T2 to the positive supply to ensure it was completely turned off when not wanted.
If you try it, keep T1 & T2 close to the loops, it isn't too important, at least for HF if the switching signal and T3 are wired a short distance away.
Brian.
For further experimentation - consider making the loops reversible so they can be used additively or subtractively, it might help to boost or reject from certain directions.
Brian.
A simple summing amplifier is all you need, at it's simplest just join all the signals together!
The phasing is exactly what you want, it gives the boost or cancellation essential for adding directivity. Don't forget that turning the same loop through 180 degrees will invert the signal it produces. The directivity pattern may be the same but if used in conjunction with another signal source it can add to or subtract from the other signal.
Brian.
Its really easy using MCUs but I know you don't like programming them.
Brian.
I wouldn't recommend that as a solution, it will work sequentially but not exclusively. It will add more loops as the voltage increases rather than allow individual selection.
Brian.
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