Don't be so hard on yourself mate. There's always room to learn and at the end of the day you can only do what you lnow with what you have.
I know it ain't ideal or lab spec but would get you that stable signal you need to give your tests more meaning to you. Which is what is important.
We all come here to learn, share and question.
No-one knows it all, no-one ever will. You just got to open your mind that others may have worse or better ways than you or I have.
Its a handy wee tool. I use it on my mobile. Comes in handy setting alc etc and like I say would give you the constant signal you lack either from phone or pc. It also has a hearing test on it. I can hear to 17.5khz but theres a couple of dips in my hearing range where i hear nothing then it comes back.
A friend got told his radio was 3khz off on usb and was panicking.
I said no way as its a radio I am very familiar with having 2 of them. Sure I went to see and align it if need be. With 1khz tone was 27.55603 on usb and 27.554.06.
Wasn't even worth opening radio for 30/60 hz. No doubt person who told him confused tens of hertz with khz.
But put his mind at rest seeing as it was even closer to spec than a 148 he had next to it that was 40 off on usb and 30 on lsb. It had just been serviced by one of the best rig docs in uk.
Allowing for accuracy of my counter and phone tone it could have been almost dead on, on either radio.
It certainly comes in handy if you just want cb accuracy or ballpark power readings.
End of the day if you don't question you don't learn, and we all interperet what we read differently anyway.
Curiosity killed the cat. But it helped me work the world. In my teens all I did was question everything. Now I read a lot. Your mentor was right to teach curiosity, caution is also a wise trait as I've found out being blown across room twice with mains voltage. 240v kicks some major ass. Lol.
Teach me to change a valve linear fuse whilst stoned and still plugged in. I was 15. I ain't done it again. Lol 
I'm a firm believer if it ain't drastically off don't touch it.
Jazz 73
