If you want an inexpensive amp that "good enough" for such testing, run by Walmart and pick up one of these:
https://www.walmart.com/ip/Onn-Indoor-Passive-Antenna-Amplifier-Onb17Ch001/248780245
On second thought, pick up two of them. The first one I picked up for analysis was dead. Second one was okay.
Rick,
Sounds like you may have the HDA-200.
Do be cautious with amps that are "adjustable". Most of the ones that I've examined simply put a variable attenuator in front of the amplification module which really ruins the noise figure at the amp's input. I haven't examined the HDA200 to see if it's done that way or if they engineered it to truly vary the gain without affecting the noise figure.