What would be best to have for receiver alignments a function generator or a RF signal generator? Right now I have an Eico 324 not the most accurate instrument around and after a good hour of warmup time its fairly stable, but unit does suffer from microphonics. Been looking at some of the older military sig gens, some older HP, and Fluke sig gens, and a few of the new function generators available today at reasonable prices. I need something that goes below 100Khz, with the ability to modulate the signal as well. What's the plus's and minus's between the two types?