I've built AA5TB's antenna coupler for a 5W 20m transceiver.

Tuning was kind of difficult because my transceiver has buttons for sending a dot and a dash, but no tuning mode, so I couldn't have the transmitter on permanently to tune easily. I had to tweak it a bit to make it do this. I also have a 7.017MHz calibrated transmitter. Would it be okay to put the transceiver in receive mode, on 14.034MHz, hold that calibrated transmitter close to the antenna, and tune until the signal is the loudest (or, until the LED doesn't light / the voltage measured over D2 is in its minimum)? So in other words: can I tune the antenna when not transmitting?