I may get in trouble here.....but I don't think you can do the "double tone" tests with a typical signal generator. you'd have to have two...and feed them through some sort of mixer/balancer.
Good point...
When it comes to SSB "alignment" - usually a good pair of ears usually can spot the challenge and re-tweak the right coils and be on their way.
Mostly by using two radios - one becomes the "reference" for the other - and once "centered" the reference radio can then have it's audio opened thru the radios' cheap speaker - to "squeal" a feedback squeal - back into the other radio - a simple O'scope can show the waveform from the output RF sample of the Tested radio - shown up in the RF signal the other one transmits - revealing what it's hearing thru that microphone on the Test radio - from the quality of feedback squeal the Monitor Reference radio sends thru it's speaker.
- But, when you have a bad coil or caps or even a Filter like those used in the Cobra 148/ Grant XL - those types of lattice filters can really be hard to diagnose and correct.
Yes, you can correct them, but it takes knowing which Crystal, or BPF coil - is causing the condition...
Not something most can easily do without such a tool. This can help those alignments that have poorly aligned Xtal filter networks - can spot the bad xtal thru the sending frequencies of it's expected (stamped) resonate frequency and what the new one is - the drift shows up as a peak in a different part of the spectrum display - then the tech knows he's got a bad one - either replace or repair.
But it's a serious tool for those that have the know-how to apply this tool to the problem - I've just described one "kind" of condition I could use something like that for, but it is not for everyone.
Once you have an idea - the rest is up to the tech in pulling it apart and finding the mistuned Xtal - you can fix it by trying to pad capacitance in Series or in Parallel - then observe the results thru the tool.
- - if the Xtal can be re-tweaked back into slot - response curve(?) It takes a device like the above to find it's resonate frequency - then apply caps (or tweak the coils) to drift it back into where it should ring true to for the network.
This tool is for those INTENSE moments in Tents...when you have to Field-medic a radio...