DIY 2.4 Ghz impedance equipment site help

Hi all, I saw a site where a fellow designed a unit to measure impedance at 2.4 ghz, for use on wifi antennas. I don't recall if it was return loss or impedance. It gave detailed instructions on how to build and also had ready built units for sale. I think it was a ham that designed the unit. I also think he was not in the states, possibly a P or PY call sign, but the memory is not good! Any help would be appreciated. Thanks, Mike

Reply to
amdx
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This one?

or one of these:

What I do is use a return loss bridge as in:

I've built several out of chip resistors and junk parts. I have one that works well up to about 8GHz. Great for testing antennas. That's what's inside a Telonic Rho-tector (which can usually be found on eBay for cheap). A few models go up to 2.4Ghz.

You'll also *might* need a microwave load or three. 50 ohms for a reference, but also some other known values for calibration.

The problem is that you'll need an RF sweep generator to use this effectively. It's also not a VNA (vector network analyzer) so it won't tell you if any reactance is capacitive or inductive.

Reply to
Jeff Liebermann

Thanks Jeff, This is the one I wanted.

Reply to
amdx

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.co

I just use the HP9753B Network Analyzer on that bench...over there --> on that wall.(He-he.)

You can get great deals on good used equipment here:

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Sometimes 10% (or less) of the original selling price.

I just picked up a $23K

Reply to
DanS

I think you mean HP8753B NyetWork Analyzer. $3500 for the A version (used). $13,000 for the D version. You must think I'm getting rich answering questions on Usenet.

Not too horrible prices. Thanks.

Congrats and I'm jealous. I've seen the test equipment pile in some of the local cell sites. One site has a rack of dedicated "monitoring" equipment that is powered on, but rarely used. My guess is about $100K+ slowly depreciating. Another site has two almost identical HP8920B service monitors just sitting there, owned by two of the cellular companies. I've been told that at one point, there were three, but the third one went away after an upgrade.

That's what computer control is really all about. Using a real keyboard is sometimes easier than using the front panel.

My taste in test equipment is towards cheap because I don't currently have a paying project to justify (and deduct) the capital equipment expenses. If I need it, I try to borrow it first. If less than 3 months, I rent. If more than about 6 months, I buy (used). If in between, I agonize. Meanwhile, what I have is starting to look like museum pieces:

Those are rather dated. I also have some new test equipment. Updated pictures when I have time.

Reply to
Jeff Liebermann

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

I did mean that.

To be honest...that's why I posted !!!!!!! Of oucrse you know it's not mine, but the company I work for.

There's nothing wrong with old test equipment, and as a matter of fact, the new SA is a modern digital one, but not the one I wanted. I wanted the boss to buy the 20 year old analog Tektronix SA...one with a scope section and then other sections plug in depending on what you need.

The response time on the old analog one was much faster.

Reply to
DanS

7L13 or 7L14? That's the only Tek plug in models I recall. Also a TR502 tracking generator. I only played with these for a short while and don't really know much about them.

I kinda prefer HP (for no obvious reason other than familiarity).

Yep. You can also take them out of calibrated sweep mode and do all kinds of nifty tricks that are difficult, illegal, or impossible on the computer controlled SA's. I'm debating the merits of buying a

10Ghz plugin for my HP140T SA, or just getting a new SA.
Reply to
Jeff Liebermann

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

You call THAT one old ? The one that just crapped out was an older version of that. At least that one has a digital readout for the frequency center !!!!

Here's the old one:

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When I first started with the company in 1983 they used this particualr piece. I left and came back to the company, a couple times, and I was STILL using that one up until 6 months ago.

I'm really suprised it lasted that long, the tech that used it from 1982 thru 2004 really liked to spin those knobs....in an out-of-control manner.

Reply to
DanS

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