Its almost impossible to predict what antenna spacing and power level is the maximum your scanner can handle without damage, but you can predict the power level it sees.
Your 82w transmitter is 19.13dBw and at 146MHz, the path loss at 1m using 0dB gain antennas is 15.72dB loss, leaving 3.48dBw or 2.19w into your scanner, not counting coax loss, etc.
Since this is in the near field, calculations can be off quite a bit in either direction and this is just to get an idea of how much power can be coupled between to close spaced antennas. I used 0dB gain antennas in the calculation and if your antennas have any gain, the coupling will go up by that much.
If you double the distance between the antennas, the coupling will go down by 6dB or four times, but at your spacing you are probably still in the near field where RF behavior is difficult to calculate. You could also put a wattmeter and load on your scanners coax and directly measure what power it sees when you transmit. That is an absolute measurement you can count on.
I would not want to subject my scanner to several watts at its input connector, especially when its receiving in the VHF band and its tracking filters would tuned there.
prcguy
I've been reading on our forum about how far my wideband scanner antenna should be separated from my transmit antenna and it seems like the answer is "as far apart as possible" but not any closer than about 36". Both antennas are mag mount and I measure the max output of my radio at 82 watts on VHF 2m. My transmit antenna is 5/8 wave dual band for UHF/VHF. I have my antennas separated about 38" right now and have not noticed any scanner problems yet. I have a BCD436HP and an old BCT8 and obviously don't want to do any lasting damage to them. Am I looking for trouble with this setup?