[IanG3XYV]

I have two 8901As which is one more than I really need. They are superb instruments and do a lot more than just AM and FM modulation percentages, including digital frequency and RF power measurement. Your B model does audio AC RMS voltage and has a built in modulation calibrator. They have a host of special functions that help check out operation but they are very easy to operate in automatic mode for the most needed measurements.

Being HP there is excellent documentation and you should easily find online operation and service manuals if you don't already have them. You'll have a lot of fun with it.

Bird Tenuline power attenuators are good quality and conservatively rated. It will do fine for your lower power measurements but if you plan on testing at an RF output of 100W you really need an attenuator rated to handle that and 30dB would be a better attenuation.

I note one of your options puts the main connectors on the rear panel. This is not so convenient for normal bench use but I'm sure you can work around that.

Enjoy your instrument.