[ADTech]

Buildings and trees can take another 10-40 dB off the signal power, depending on individual circumstances.

A spectrum analyzer is the preferred instrument for working with and examining RF signals, but they're not inexpensive. However, there's a used Sencore 1454 on ebay that can be had for under $250 assuming that it works as promised. There's also a 1476 SLM that's available for under $300 but its description leaves me unimpressed. Since you have a solid computer background, an computer-based SDR (software-defined radio) via USB port is extremely inexpensive but slow. Look for some posts from fellow site member "Pete Higgins" on that particular subject.

The 1296F attenuator, now discontinued, works backwards from what is intuitive. Turning the control fully counter-clockwise is minimum signal (maximum attenuation) and fully clockwise is maximum signal (minimum attenuation).