Plenty of 22VAC power supplies around.
However, given it's age, (that supply was from the 1980's) I highly recommend replacing the amp and supply.
Most new amps have LTE filtering.
65dBuV is the ideal signal level, BUT... most importantly is the signal quality.
If you have poor signal quality (eg: high BER) it won't matter how much signal level you have. In fact, too much signal is just as bad as not enough signal.
Antenna mounting location is very important if you are in a marginal signal area, as you need to obtain good signal quality at the antenna.
Amplifying a poor digital signal just gives you a 'louder' poor signal.
Many TV's can display signal meters but you need to see the screen whilst moving the antenna.
Meters with BER (signal quality) are expensive.
Yes, most regional TV is UHF.
Where are you located and what antenna are you using? If it's as old as the amp, it may also need updating.
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