This is turning into one of my down-the-rabbit-hole adventures.......
This all kinda-sorta started out when we moved here. I didn't pack my signal generator (at all), and it slid around inside the trailer I was pulling, breaking off an input level adjustment knob, and bending the other.
I was pretty sure I could fix it, but I'm glacially slooow doing this (take it apart, see what broke, find the parts, order the parts, etc, etc) kind of work, and I really wanted a newer generator with more features, so I looked around and bought a nice used one which should be here Friday.
But not knowing if my "old" generator still functioned, I set up my frequency counter and Spectrum Analyzer so I could measure the output.
I've been seriously using Spectrum Analyzers since 1982 when I went to work for Hughes Aircraft. They're a very powerful tool for radio work, allowing you to make accurate, repeatable measurements in a fraction of the time it would take using "classical" methods. I understand them pretty well, BUT......I always get things all scrambled up when going between units made by Tektronix, and units made by HP/Agilent. The HP units are very intuitive to use while the Tektronix units are more like your practical for a Master's Thesis. And the controls are not laid out in a logical grouping, and many features I'm used to having are not available on my Tektronix 494 unit. So naturally, when I first powered it up I had forgotten how different it was, and proceeded to get it into a state where it couldn't even see the internal CAL signal.
Hey, I hate this old clunker anyway, so why not go shopping for another unit, and this time buy an HP.
So I did.....
It's an HP 8594E model, and "only" goes to 2.9GHz, but that's plenty for my needs. Has a nice, bright trace....
And in general is very clean.
It's been a "Bench Unit" it's entire life, unlike some of the ones I've dragged around/banged around the ships for Sea Launch!
And even though I paid $40 for shipping, my total was $988, about half of what these go for from a Test Equipment Store.
So anyway....after buying this last night, I went back downstairs to shut things off, and gave the old 494 one last try.
Yep, the damn thing works! Here it is displaying a 100MHz signal from my old generator.
It's drifty for a least an hour after turn-on, but after that it seems stable. The Pilot Induced Problem was that I had the reference level and input attenuator set wrong, essentially making it "deaf" to the signal levels I was trying to monitor.
And the generator only has a 100HZ error at 100MHz......
I'm assuming my counter to be "accurate" as it has the best timebase on-site (one of those nifty HP Ovenized Crystal Oscillators), and it had a current calibration when I bought it some years ago.
I have a known-good Rubidium Frequency Standard with a 10MHz output, so as soon as I get that fired up, along with my HP "GPS Clcock/Timebase", I should be good-to-go for accuracy.
Having any instrument that makes measurements of time or frequency connected to a "Master Timebase" or "Master Clock" keeps them all synchronized, and helps reduce measurement errors.
So at long last, my Radio Lab will have a Tektronix Oscilloscope and an HP Spectrum Analyzer as God and the Chief Radio Engineer have commanded.....
Tonight's project is to finish up the Drake MS-4/AC4 speaker/power supply. This will get the bench cleaned up so I can make some BNC patch cables in 3~6' lengths.
Having fancy test gear is nice, but without patch cables to hook it all together, you can't do much with it. Making accessories like patch cables is a good way to save a few $$, too. I'd rather buy my connectors "By The Dozen" and a spool of cable than pay $12~$25 EACH for a cable. My cost of parts is probably less than $5, so that adds up on 10 cables. It's mindless radio 'grunt work' and not as glamorous as tuning up transmitters or bringing a dead receiver back to life, but it's relaxing and keeps me out of bars.......