Tektronix H600 RF Hawk

That's why they invented attenuators.

At first glance it looks like they are doing FFT chunks around the

If it has to be really small this one looks interesting but I haven't tried it out yet:

They also have one that includes the 2.45GHz ISM band which becomes more and more important these days.

"Joerg" a écrit dans le message de news: n_Q5k.4389$L snipped-for-privacy@flpi150.ffdc.sbc.com...

Hi Joerg, For 2,4GHz there was also a very interesting design published in Circuit Cellar two year ago, see :

Cheers, Robert

$1600 doesn't strike me as unreasaonble for the unit itself, but $250-$300 for antennas? Wow!

The minimum 15kHz RBW seems rather high to me, although perhaps they can narrow it in software so it's only a real problem if you have closely spaced signals with one or more being rather high-powered. (The newer Agilent spectrum analyzers we have go down to something like 1Hz RBW in software -- still incredibly handy!)

Do you normally recommend your clients get something with a tracking generator?

For rolling your own, the detector seems to be a straightforward application of the numerous log detector ICs out there followed by an ADC... but how do you build a particularly *clean* DC (or near-DC) to 1.3GHz (or 2.7GHz) signal source reasonably inexpensively? Use a DDS to generate, say, 0-200MHz and then mix it with some high-quality fixed-frequency carriers? (I've read that just multiplying a DDS's output directly isn't such a great idea since they do tend to have noticeably spur levels...)

This is an attractive part:

I really ought to go grab one of our old 8593C's and see what sort of spurs levels their master oscillators produce in the first place; I still suffer from having spent too long in college and thinking that "a good mixer" is "an ideal multiplier" and that "a good signal source" needs spurs levels > -100dBc. :-) I was shocked to find that a cheap old analog signal generator I own had harmonic distortion in the ballpark of -30dBc!

---Joel

Yeah, there are lots of analyzers for that band, plus the usual low-band ones that use a TV tuner but even there you can't go much below 40MHz.

Nowadays you can probably even get away with the CC2500/MSP430 kit that TI sells for $50. Has USB and all that, plus you get a remote transceiver for further experiments.

Typically not, unless they want to also test susceptibility during the same session. Mostly they've got generators for that already so why spend the extra rental fees?

I prefer a nice clean multi-loop PLL approach.

generator

My spectrally most clean generator here in the lab is (or was ...) a Rohde&Schwarz SMF. Only goes to 10MHz without mixing. But it's main oscillator tube is tired and it's one of those old WWII style steel editions. Some day I'll fix it. Maybe, gasp, put a nice RF dual-gate in there. Inside the tube so nobody sees ...

they

ange

is that -150dBm/Hz?

you need to include the BW and SR in your calculations to get to bits.

Mark

It's ~ -150dBm with 10Hz RBW.

From looking through more of the data sheet

I was thinking that it might not be uncommon to find, say, folks doing "cookbook" anti-aliasing LPF design at the output of a DAC, and you might end up sweeping the filter at times to verify it really is doing its job or something like that.

And would you be building your VCOs out of discete transistor circuits? Or looking for pre-packaged wideband VCOs?

---Joel

"Joel Koltner" wrote in news:JZS5k.192392$ snipped-for-privacy@en-nntp-06.dc.easynews.com:

AFAIK,TEK doesn't HAVE any "proprietary ADCs" anymore;they buy all their ICs from other companies. TEK doesn't any IC fab anymore.

For that I use a network analyzer because you also need to measure group delay flatness, something most spectrum analyzers cannot do.

First I'd take a look at the offerings, which ICs are out there but only from mainstream companies and where there is a chance that it won't be obsoleted in a few years. Real tough super low phase noise stuff would most likely require a transistor-level design.

They still might do in-house proprietary chip design and contract with a fab. However, I don't know whether they really do that. I just can't imagine how they'd keep a competitive edge against Asian rivals without a chip design group. Although it seems that edge has already eroded a bit in the lower price tiers and I have bought a scope from an Asian rival. Not because it cost less but because it was IMHO better.

Yeah, but I believe they're still quite "chummy" with Maxim, who bought their old fab equipment. If you're willing to accept low yields (hence, high prices), presumably you can build ICs that completely kick the butts of what you or I could buy off-the-shelf.

A handful of years ago nVidia, 3dfx and ATI were all still battling it out, the rumor was that the yields on their highest-speed GPUs were no better than

---Joel

Ah, gotcha.

Did I miss a day in school somewhere, or if you're trying to build very wideband (even a few decades) VCOs with an analog implementation (for the low phase noise and lack of spurs) -- and you're trying to do this using readily available/reasonably affordable parts -- are there any ways to do it other than using varactors for tuning and perhaps switching larger capacitors and/or inductors in and out?

This seems rather difficult to me, hence the idea of just building a handful of fixed-frequency oscillators in analog and then mixing with a DDS output. :-) It's clear to me why something like those old HP 8593s cost something absurd like $25,000 a decade ago!

---Joel

No, but maybe it was like our high school. There was a pub in walking distance and drinking age in Germany is fairly low and in those days nobody really cared. Heck, the bar keeper even gave me a malt whiskey once (after making sure I had the dough to pay for it).

Two methods:

a. Have a bank of VCOs. Since RF transistors are dirt cheap it makes no economical sense anymore to switch caps and inductors in and out. You just have a PIN diode mux and turn the desired oscillator on via it's supply. Or stop the others from oscillation but keep the quiescent.

b. The method you described below but mixing the fixed oscillators with a VCO instead of a DDS source. Not that I want to diss DDS here, it's just that this is the traditional approach and it is cost effective, avoids boutique parts and you can leave it in production until the cows come home. I have used DDS chips in the past and, well, let's say the results were "ok". But this was a while ago and Analog Devices is constantly cranking out new chips.

It's also the really low production volume. Not everybody needs this stuff ;-)

"Joel Koltner" wrote in news:1AT5k.208125$ snipped-for-privacy@en-nntp-02.dc.easynews.com:

After what Maxim did with the older TEK-made IC lines?? the forced "last-time buy" due to "low volume sales",resulting in the death of the much beloved 2445/2465 series scopes.In fact,it killed the entire

(BTW,didya know Triquint Semi was a TEK spinoff?)

Thanks Joerg, that's good advice.

My high school was squahed between an old residential district and some designated green space, so the nearest store of any kind was about 3/4 mile away... on bike you could make it over lunch, on foot it would have been challenging.

I have a friend who went to a high school situated on a rectangular lot with one "bite" out of the corner that was a convenience store/sandwich shop. Talk about guaranteed income!

In Linus Torvald's book he discusses how one of the local (Helsinki) convenience stores was willing to run tabs for students, so of course that's where msot of his Coke and donuts came from. Nice idea, given how irregular income is for students.

That AD9911 I linked to looks attractive -- DC-200MHz, and real thought given to dealing with the spurs.

---Joel

Hi Jim,

Ah, ok, "chummy" probably isn't the right word then.

But I know that Tek -- at least as of a few years ago -- was (1) still designing new custom ICs for their high-speed probes and (2) still using older custom ICs for probes, the TDS3000 series, etc. as well. I infered that was through Maxim, but perhaps that isn't the case!

That is a bit slimy.

Yeah, they have some pretty nice products if you're in the rather nichey markets they target. Oh, and I like their multiple full-page ads in the trade rags that give you a little "feel good" bio about their employees, highlighting each oe's contributions -- especially since they were smart enough to realize that the folks doing, e.g., shipping and receiving are just as worthy of being "published" as the hard-core engineers are.

But of course I'm a sentimental kind of guy who enjoys that sort of fluff. :-)

Are you still working at a big company, Jim?

---Joel

One other question, Joerg -- any recommendations on PLL manufacturers? I've used Analog Devices in the past with smoewhat mixed results; National Semi seems to be common but the chips aren't as "flashly" as Analog's... Fujitsu has some neat-looking parts, but I'd worry a bit about availability.

---Joel