John Foege wrote:
I have recently started to build an electronics lab, and am currently
trying to acquire test and general equipment for my little basement
workshop of horrors.
John, I hope my first post on this Forum will be useful to you... I was
in your same position two or three years ago.
I have to say that ebay is really handy, but I suggest you first to try
with swapfests and flea-markets. There you can speak with the seller,
and _ask_ for a demonstration if there's a AC plug close by.
My only suggestion is: buy what you need now, and save money for the future.
Oscilloscopes
If I'm not wrong, Tektronix is selling its entry-level models at around
1000$. I have a TDS 210: small, portable, fits 100% the requirements for
a general purpose scope. However, I use most my old Tek 475A (analog,
>200 MHz bandwidth)
Spectrum Analyzer
I have started with a HP 141T system, a real workhorse (and reparable).
The 141 is actually the mainframe, then you need the 855x series
plug-in. One (8552) is the IF, the other the RF plug-in.
With the 8555 you can go up to 18 GHz. In this case, I'll consider the
8445 preselector.
They are still worth 500$--1500$ depending on the plug-in and accessories.
Now I have a HP 8566A (100 Hz-22GHz) which I payed a little more of a
complete HP 141 system. My father has a HP 8568B (100Hz-1.8 Ghz), that
one is less expensive.
Signal generator
I'll consider building a DDS generator kit for frequency <150 MHz.
Analog generators/sweepers are relatively cheap, but they are not stable
in frequency.
If your target is high frequency, the HP 8620C sweeper series is a good
compromise. Get a "C" mainframe, get the 86222 and 86290 plug-ins and
you can sweep from 10 MHz to 18 GHz. 8620C+86222 run at about
300$--400$; the 86290 can go up to 500$ (watch ebay for deals).
If you buy an EIP source-locking counter, you can phase-lock them.
Lower prices for the heavy, old BWO-based HP 8690 sweepers. I can't
recommend them, unless you find a good deal, with the complete plug-in
series.
If you need a synthesizer, HP models are generally more expensive (but
also more fixable, in general) than Marconi, Giga-tronics and Fluke.
I have a Marconi 2019 (80 kHz-1040 MHz) and it works fine and it's clean
enough for my needs.
If you buy one, make sure it's 100% working, they are tricky to fix.
Network analyzers
Wonderful instruments. Very sophisticated. People still write entire PhD
theses on their calibration theory.
Please don't take it badly, but if you don't really know how to use
them, you don't need them, since a spectrum analyzer and a tracking
generator will solve your problems and save you a lot of money.
However, if you want to acquire some pieces of history, look for the HP
8410 from 1970's, it uses the 8620 as sweeper: the HP8412 display + 8410
IF should go for 200$, S-parameters test-set 8745 (0.1-2 GHz) or 8746
(0.5-12/18 GHz) for 300$; the 8511 sampler converter is about 100$: get
at least two.
If you have money _and_ you need it, the HP 8510C is the best VNA ever
made. But the 8510 is just the display (85101) and the IF (85102), you
need a sweeper (8340 or 8341 or newer models) and the test-set (8515,
8514 etc) AND the interconnecting cables.
Once you have all that, you have a Ferrari without tires.
You need at least two test cables, calibration grade adapters and
calibration standards... new tires will cost much more than the
second-hand Ferrari.
Both instruments are reparable, if you don't blow up the unobtanium RF
parts (samplers and pulse generators for the test-sets, wideband
amplifiers and YIG oscillators for the source).
(By the way, new VNA models from Agilent, Anrits, R&S all have an
embedded PC with MS Windows and a hard drive.
This simply means they are not designed to last 20+ years, but perhaps
it's not fair to compare them with my HP 8510B...)
Oh, yes... one thing more: a PC with a National Instruments GPIB board
if you plan to automate your measurements.
Good luck
Marco Garelli, AI4YH
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