Rigol DSA1000 Spectrum Analyzers

$5k price tag on a 3GHz spectrum analyzer seems too good to be true. Unfortunately I can't find a single mention of these on the web. Are these units worth a shot if you are on a tight budget?

The phase noise is fairly putrid-- -80 dBc/Hz at 10 kHz is more than 30 dB worse than my HP 8568B ($1400 or so on eBay). It does have a nice colour LCD display, and you don't need a cart to carry it on, but good luck doing any close-in work with that.

Cheers

Phil Hobbs

...that's probably why their minimum RBW is 100Hz!...

As Joerg likes to point out, though, many people just need spectrum analyzers for compliance/verification work and can get away with far worse specs than someone trying to do high-performance design work.

These guys don't even tell your their phase noise specs (other than mentioning in an FAQ, "At 1 GHz RF, you typically experience -55 dBc/Hz @ 10 Hz offset using the internal timebase..."), and I bet they're selling a bunch:

---Joel

Yeah, it sounds much more like a prettied-up Tektronix 7L12.

Cheers

Phil Hobbs

he $5k price tag on a 3GHz spectrum analyzer seems too good to be true. =A0= Unfortunately I can't find a single mention of these on the web. =A0Are the= se units worth a shot if you are on a tight budget?

If you're *really* on a budget you can lash an old cable box tuner to a sawtooth generator and a 'scope. I did that for a quickie waayyy back. It was good enough for measuring transmitters, which was what I needed. A clock oscillator driving a pulse circuit made harmonics for the display's calibration marks. Total cost was negligible.

-- Cheers, James Arthur

That's true but it only works in quiet places. Uncle Leroy's metal shed and such. A couple weeks ago I had to do some some pre-compliance checks at a client with a building right next to a busy runway, in a very densely populated industrial area. There you need all the phase noise performance and the lowest RBW you can get. That was not fun.

"Field" trip?

Not from an area where 50 miles can take you north of two hours :-)

Screen room ? ...Jim Thompson

Yes, they are planning to get one. Some of my clients are start-ups.

We have a couple of screen rooms. They've found them to be far less useful than anticipated. ...all that metal... ;-)

The most imaginative use for a screen room I remember was by an electron-microscopist at Watson in about 1985. (This guy had personality problems that would make him a natural for SED--he eventually got fired about a dozen years ago, for doing a Phil Allison on the president of a major university.)

Anyway, because the lab was expanding so fast, they kept moving his lab, which is kind of tough on electron microscopes. So, he got this really big screen room installed, so they could never move him again. He just sat there and got stranger and stranger, till they canned him. I don't know if the shield room was responsible, but it sure was gloomy in there--dark oxidized copper walls and steel bars.

Cheers

Phil Hobbs

For noise hunts I find them very useful. It sure cuts down on chasing ghosts, where some obscure interferer turns out to be from the computers next door. Same for pre-compliance. You close the door, do a sanity check with a portable radio, and you can be 99% sure that all the remaining crud originates at the DUT. The other 1% might come from the displays of spectrum analyzers of "reputable manufacturers". So best to use a boat anchor analyzer in there. Seriously.

I hope he got some help, sounds like he needed or still needs counseling. If people mouth off like that I often pray for them.

Most likely there's much more serious underlying problems that plague him. Unless he finds a trusting and listening ear it's unlikely to get better on its own.

As for screen rooms, I find that a lot of them quickly degrade. Not because of materials issues but because they are used as an extended lab. Computers and lab gear encroach. Then one day you want to noise-hunt a problem unit for a client and folks say "Oh, but you can't turn off that computer over there". Great ...

They bought them to test radios, not thinking about reflections. They're still testing them by walking them outside. They built a gazebo out in the woods in case it rains. ;-)

When I was doing some pre-compliance stuff at IBM I found the best location was a corner office in the corner of the complex, out by the deer and moose. They wanted to put me on an abandoned raised floor. What a mess.

You can get absorbing foam blocks but the room needs to be large, the cerrated foam pieces tend to attract dust, and they are a bear to clean. Oh, and they are expensive.

Way to go. I hope they mounted a barbecue next to it :-)

That's the reason why many EMC labs are out in the boonies. I like CKC Labs in Mariposa. It's right next to Yosemite National Park. The town is kind of nice as well. Nobody would flinch if you'd ride up to the saloon on a horse. Live country music, western dancing, booze, saloon fights, the works ;-)

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They wasted $50K or so on those, too.

No, but that's an idea. There is a park with a small lake across the street. When I take the radios out I take a walk in the park.

The ones we go to are on the NE side of Atlanta, a couple of miles from "Spaghetti Junction" [1]. Not exactly in the boonies. No horses, though there probably are a few "gentlemen's clubs" around.

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my standard line for 25 years is that screen rooms are to keep out interference .... but not RF.

They keep it *in* real good! ;-)

I was in Pleasanton and spotted a truck that indicated it was a mobile compliance lab. I think it was run by TUV.