Hi Dorin,
Not sure if you've gotten your question answered, but the best and safest way to ensure that you're not too close to the Rx with the ignition is to do a range check with the engine RUNNING. This way if there's any noise interfering you should be able to see it before you're in the air. You should always try to keep it as far as you can from the Rx, but the unit is decently well shielded. The spark plug high voltage wire is more prone to causing inference so try to keep that away from other electronics if you can.

Thanks,
Jimmy