[Eric]

Going form 82 or 85v to 90 isn't going to change anything to terms of the volume. Now if you where going from 100v to 180v on the 71A that would increase the volume some. If you have a pm spkr & output transformer I'd give that a try instead of the horn. The horn may not be working up to it's full potential.
Looks like you have a resistor solder across the gird leak , what value is it?
Back in the '20's the common type the antenna was two poles extend from the two farest point of the roof. A wire extended across both poles and then a down lead to the set. In total about 70-90' and up 35-50' high.

Terry

I only have about 15' of ant strung in my garage so that may be a problem, in fact I use a signal gen to help me zero in on stations and when hooked to the ant lead I get a boost in volume. That resistor is 330k (all I had) the original Pilotohm 300k is open look as thought they used it as a fuse as it has a glass body.