There are several portable “HD” antennas being advertised on television that promise miracles, but avoid them. Your existing crank up is still good for the new channels and new tv’s. No need for a new antenna in either location based on the little info, unless broken or corroded.
Before swapping anything...
1) Check all connections on both antennas for corrosion and address if needed.
2) Check antenna wires or coax for breaks, make sure in good condition.
3) For the crank up antenna I’m assuming is an old Winegard Batwing style antenna. The is a relatively cheap add on component you might try called the wingman.
I think you would be best served getting rid of the analog TV and the converter and buy a new one which are very cheap and going on sale due to Thanksgiving and Christmas.