Rohde & Schwarz CMU200

[ZL1CVD]

Just upgraded an 8924C for a CMU-200. It has a fault - internal RF loop path 1 test fails. Does anyone have any ideas where I should start? Also does anyone happen to have service manual with circuits - the one i have is missing all module exploded diagrams and circuits. Next step for me it to install a SSD. Cheers.

[Nuno_pt]

Not very easy to find that detail manuals in the R&S stuff.

Try run RF Self Test < http://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_news_from_rs/167/167_CMU200selftest.pdf >

I'm also looking to buy one of this because of the Spectrum Analyzer and Tracking Generator till 2.7GHz, and also for the Audio Part, so I can measure the RX sensitivity of the radios with Power at 10dB Sinad.

 

[ZL1CVD]

I have been playing with it for a few hours now. I ran most of those tests and all reported fine except the RF loop back.

There is no tracking generator that I can find. Also no RF demodulation which is a big shame. So for general ham radio use, you have spectrum analyzer, RF generator & audio generator/analyzer.

Spectrum analyzer is very nice and allot faster than the older HP's I'm used to (8924 & E8285). But these older HPs still offer allot that this doesn't. Well, that I haven't found yet....

[Nuno_pt]

The RF Generator or Signal Generator from what I see can be use to be feed in the unit, to measure one filter, and don't know if it will track?
But for some prices of this units, an SA, Signal Generator, and Audio generator and analyzer, it's ok.

Some findings, from what the CMU have:

" The CMU200 is great bench-top unit. The RF gen covers 100kHz - 2.7GHz (0.1Hz steps, -130dBm to -27dBm up to 2.2GHz, -130dBm to -33dBm between 2.2Ghz and 2.7GHz), the power meter covers the same range in wideband mode and 10Mhz to 2.7GHz in selective mode, and measures depending on the input and type of signal from -80dBm to +53dBm (calibrated, not unleveled). The SA goes from 10Mhz to 2.7GHz, the span from zero to full (which many vector SAs in such testers can't do), RBW is from 10hz to 1MHz in 1/2/3/5 steps. My unit is the newer model with USB instead of PS2 ports for a keyboard and has the optional 2nd RF generator (same range as the first one) and the optional audio generator/analyzer (20Hz to 20KHz) which is nice. It's fast and has a clear and intuitive UI.  "

[ZL1CVD]

Yes it has all that but I can't see how to make the gen track. And yes, have to agree, for the price I paid, I did get a good deal.

From what I have read, some are saying the CMU200 PSU are starting to fail also.

The CMU screens have RF shielded glass in front of the TFT - mine has deteriorated badly - a green oxidization from edge working its way in. Replacement from R&S will be mega $$. I've just pulled it out and will get the local glass shop to cut a bit the same size. I'm not worried about emissions and this environment isn't going to create anything that will effect the measurements I make with it. 

For all its greatness, I can still pick up and E8285A or 8924 for around same price and they do allot more - but allot slower and will need almost all electro caps in PSU & display changed. The CMU could easily do the same as the hardware is more than capable. I wonder if its possible to hack its software to add features....

[Nuno_pt]

From what I can see the RF Generator (Signal Generator) is not an tracking generator is because the CMU is a VSA and not one sweep spectrum analyzer, you can make the RF Generator produce an -10dB to one frequency across the DUT and watch the result on the SA.

But will not sweep across the spectrum, like the DSA-815.

But I agree for the price that some run, get one SA, Signal generator, audio generator, THD, etc, it's a great deal.
For watching filters, see tolerances in the radios with the RF generator, and audio generator with 1kHz.

I'm looking for one too, then one Communications system tester, like IFR or Motorola.

[Wuerstchenhund]

There is no tracking generator that I can find. Also no RF demodulation which is a big shame. So for general ham radio use, you have spectrum analyzer, RF generator & audio generator/analyzer.

It doesn't have a tracking generator, simply because it's a communications test set designed for digital communication standards like GSM, W-CDMA, Bluetooth or GPS. What it has are one or two (depending on the options) RF generator(s), a Spectrum Analyzer (sweeping VSA), an RF Analyzer, a power meter (wideband and narrow band), and a 20 tone audio generator/analyzer, all in one box.

You can replicate the tracking generator if you connect the CMU200 to a PC and command the RF generator via software to "sweep" through a  frequency band while the SA is set to max hold. The dwell time for the generator needs to be larger than the sweep time, so it will be slow. But it works.

Much easier and quicker however is just using a wideband noise source, which you can even build yourself.

Spectrum analyzer is very nice and allot faster than the older HP's I'm used to (8924 & E8285). But these older HPs still offer allot that this doesn't. Well, that I haven't found yet....

8924 and E8285 are older test sets that, while supporting early digital standards, were pretty much designed for the analog communication systems back then as well as cable and antenna testing, and because of that they offer more analog functionality than modern comms test sets like the CMU200. However, they also come with all the typical disadvantages that many other cell phone test sets come with, like split frequency bands with gaps or forced coupling of RBW and span for the SA part, which actually makes it more like simple "spectrum monitors", not full scale SAs.

In comparison, the CMU200 offers a full scale SA with single frequency band without "holes", and the SA lets you set span and RBW independently as it should be, and optionally even shows you the I/Q components of a signal.

If TG-like functionality is important then have a look at the AGilent E7495A/B, which is a portable unit with a VSA (2.5/2.7GHz), an RF generator, an AWG and a wideband noise source so it can act as a Network Analyzer, as well as a GPS Reference.

[ZL1CVD]

Thanks for the comments Wuerstchenhund, very helpful. 

The more I play with the CMU200 the more I can see its going to be a great addition to my bench. I now have a SSD on order along with replacement RF front end & B11 OCXO. Wide band noise source is now on the to-do list. Then to look into connecting & controlling it with the PC.

The R&S CRTU-RU also looks like something to save up for..

[Wuerstchenhund]

The more I play with the CMU200 the more I can see its going to be a great addition to my bench. I now have a SSD on order along with replacement RF front end & B11 OCXO. Wide band noise source is now on the to-do list. Then to look into connecting & controlling it with the PC.

I think R&S has some Windows programs for the CMU200 (FreeRes?), but I've never used them. Maybe they

The R&S CRTU-RU also looks like something to save up for..

Not really, because it's pretty much just a CMU200 with an additional Windows 2000 partition for automated cell phone testing but without the audio generator/analyzer. So unless you plan to do cell phone production testing it doesn't really offer anything above the CMU200.

[Nuno_pt]

Wuerstchenhund, can´t the RF Generator be feed into the CMU across the DUT on one given frequency and watch on the SA.

Like the DUT is an BPF for 144MHz, and you feed the RF Generator across the DUT and watch on the SA.

Can you post some images of yours.

[ZL1CVD]

I'd like to also get CRTU-RU as it is running Pentium III 933MHz vs Celeron 650MHz, has front panel USB slots and more RF options fitted as standard. Having windows installed, it should also have drivers for the hardware and hopefully DLLs I may be able to use with something like Delphi.
Does anyone know if the CRTU-RU has a touch screen?

[tmbinc]

The CRTU-RU does not have a touch screen, and the Windows driver unfortunately do not expose necessary functionality for SA (RX sweep, for example).

[Wuerstchenhund]

Wuerstchenhund, can´t the RF Generator be feed into the CMU across the DUT on one given frequency and watch on the SA.

Like the DUT is an BPF for 144MHz, and you feed the RF Generator across the DUT and watch on the SA.

Sure you can do that, no problem. But usually a single frequency isn't helpful, so you'd probably want to 'sweep' through a certain frequency band. On the CMU200/CRTU-RU, you'd have to do this either manually (i.e. scroll through the frequency band slowly with the rotary knowb) or better, do that with an external PC which calls up a list of frequencies.

Can you post some images of yours.

What kind of pictures? I don't have mine any longer as  the 2.7Ghz bandwidth wasn't enough for my needs but I might still have some photos of the device and screenshots.

I'd like to also get CRTU-RU as it is running Pentium III 933MHz vs Celeron 650MHz, has front panel USB slots and more RF options fitted as standard. Having windows installed, it should also have drivers for the hardware and hopefully DLLs I may be able to use with something like Delphi.

The CRTU-RU doesn't have more options as standard as the CMU200. Both share the same instrument platform, the differences are that the CRTU lacks the audio generator/analyzer and instead of the speaker comes with a passive RF splitter/combiner.

The Windows software is made for automated testing, i.e. scripted test procedures. For that it uses Microsoft Visual C/C++ as an editor. The capabilities of the Windows drivers are simple, i.e. it lets you select an input/output and put the instrument in a certain state, but as far as I know you can't access the low level functionality of the various subsystems (RF generators, RF receiver, audio analyzer, power meter) so writing your own 'spectrum analyzer' application isn't possible.

Also, although the platform itself is identical to the CMU200, CMU200 modules normally don't work in the CRTU and vice versa.

Does anyone know if the CRTU-RU has a touch screen?

No touch. As I said, it's pretty much the same hardware as in the CMU200.

If you want a faster 'PC' (called 'FMR' in R&S speak) then I'd rather look for a newer CMU200 than a CRTU, as the CMU is more versatile.

[msraya]

Hello all!!

I have one unit that comes to me the next friday with B11(simple ocxo),  B41(audio analyzer) and B95(second RF generator)...  I am looking for KingSpec ssd pata cheap chinese units in aliexpress right now..

I printed the user manual and the service manual and I'm studying it right now... I come from RIGOL DSA-815 and Stabilock 4032...  I'm interested in program it using VISA library in Python, in order to measure several classic parameters in LNA, mixers, etc.. 

Did you write a review for the instrument, Wuerstchenhund??

Very nice instruments, indeed..
Manuel

[ZL1CVD]

I'm looking for a CMU200 user manual that covers the standard analog features - sig gen, power meter, spec an, audio an, etc. What I have here is service data and manuals specific to various GSM & CDMA options - which this one has. Want to get more of a handle on basic stuff like navigation, changing units of measure, Etc. Can anyone share a link?

BTW my screen had badly oxidized screening around edges. Replaced with standard 3mm glass cut to 185x141mm square. Its not screened but doubt this will effect home workshop use. Looks 100% better.

Also have a 32GB KingSpec SSD on order - huge overkill on size I know but will give me room for DOS, Windows & Linux partitions. 

Cheers, Chris - ZL1CVD

[_Wim_]

The manual you need is 1100.4903.12-04, but I cannot find a direct link online and it to big (16Mb) to attach here. If you sent me a pm with your email address, I will sent it to you.

[_Wim_]

Has anybody found some reference about the max DC input voltage the CMU200 can handle. The only thing I have found about this is this thread: (https://www.eevblog.com/forum/testgear/crtu-ru-input-coupling/), but so far I have not been able to confirm this is correct and applicable to the CMU200 also.

[msraya]

Hello everyone!

I get the equipment and I test it.. Hopefully the unit is working well except for some uncalibrated power measures.
The RF generator and RF spectrum analyzer is nice, the DANL is not bad and outperforms my RIGOL by a little..

The main problem with the unit is that it cannot make Audio analysis and RF analysis at the same time.. so I cannot adjust FM equipment with the RF generator and SINAD meter, nor I can use an external demodulator over the IF output and at the same time do deviation measures with the Audio analyzer.. 

I think I will need the AMPS extensions K29    and that must be purchased separately.. so only RF generator, selective Power meter, frequency counter, Spectrum analyzer, Audio Generator and SINAD meter for me is enough..

So if someone can get both measures working at the same time, please give me advice..    ..
No audio test in GSM is not working for me 

For _Wim_, basically no one RF Spectrum Analyzer accept DC voltage in input.. Remember that is has a 50ohm resistor in input, so more that aprox 5VDC burn the resistor... So if the equipment does not have DC block capacitor, as is the norm, you will have to supply one.

For ZL1CVD, yes all manuals are online.. so no problem to find how it works..

R&S have Windows programs in their web page to use the unit as tracking analyzer, and to make some GSM, WLAN, etc.. complicated measures.. (power, occuped bandwidth, etc).. You need serial cable o GPIB card and cable..

Regards
Manuel

[ZL1CVD]

That is good you have CMU200 now msraya

Mine has K29 which is just software. K29 need hardware CMU-B54 v14 which I have. I will see if i can figure out simultaneous RF & audio analysis.

I now have all manuals - user manual was not on R&S website nor could I locate it through google.

For windows software I am not looking to use GPIB. I would like to talk directly to the DLLs - for me Delphi or Lazarus would be the go as I'm not good with c. I suspect this may be beyond my abilities so may have to fall back to serial GPIB.

I'm in the processes of ordering a R&S CRTU-RU. It has windows loaded and looks loaded with RF cards. It certainly has the connectors for the I/Q output so I suspect (hope) CMU-B17 analog I/Q is fitted. This should allow me to play around with a an external Teensy SDR SSB/AM/CW modulator / demodulator. 

When _Wim_ asked about DC voltage I also thought ohms law which would mean on 2W input @ 50 ohms a max of 10V - unless of coarse there is a blocking cap which I'd have thought would adversely effect the frequency response?

Cheers for now!

[hoangviet]

Hi everybody

I just bought 3 dead CMU200 from a mobile company. They both had faulty PSUs but i manage to repair 2 of them which had issue with standby PSU, only faulty TOP200YN converter IC 

One unit had a Non-volatile Ram Empty error with Model CMU XXX and no Serial, work with only basic function, my guess would be the PSU fail at the time they update the firmware. In version manager i do see a choice to copy NVRAM to disk, but couldnt find the other way back 

The other unit work ok with all software option at start, but after few days the start-up process stuck at BaseDiscoverOptionsEnd with the Link LED in Digital Board blink sometime, i had trace the problem to the Digital Board by exchange with other unit but dont have any info to debug it. Anybody have the same error like this one ?

[_Wim_]

So if the equipment does not have DC block capacitor, as is the norm, you will have to supply one.

That was my question, does it have a DC-block capacitor? I currently use an external one (and an external attenuator if I do not know the signal level for sure), but as the unit is already quite deep, these screwed on attenuator are impractical and I would like to avoid them.

[_Wim_]

When _Wim_ asked about DC voltage I also thought ohms law which would mean on 2W input @ 50 ohms a max of 10V - unless of coarse there is a blocking cap which I'd have thought would adversely effect the frequency response?

As the CMU200 start only at 10Mhz, a DC blocking cap should not interfere with the frequency response if properly chosen...The 2 watts indicates a max 10V RMS signal or max 33 dbm (but not necessarily dc).

[msraya]

Yes, the blocking capacitor is a sensible theme..  Some spectrum analyzers get burned easily as the Tek 492.
For troubleshot RF circuits, I always use my HP85024A RF probe.  O0

I think is possible to use both functions: audio function and RF generator at the same time using GPIB programming.. but yet not try it.. I will post the info when I get it.

I need a macro o programing feature in the unit.. I will attach a PS2 Keyboard and press ALT-F4 to see what happens    I don't think The inside PC can be programmed directly in C or whatever.

I have the operator's manual and it includes all programing information, but it weighs 16Mbytes, please drop me a pm and I send you via email..

Manuel
 

[ZL1CVD]

Hi Manuel
I do have operating manual 1100.4903.12-06 thank you.

Alt-+F4 drops back to MSDOS. You can then run standard MSDOS programs. So anything you write with say old Turbo Pascal runs OK.

I tied to install Win98 and got through 1st decompressing & loading but it failed to boot into 2nd part of install - I didn't spend any time looking why. I had forgot to update BIOS with PNP OS and remove video caching which I recall from past caused 98 to hang on some machines. But I was also using a dodgy IBM 2.5" HDD. I'll wait until I get a CRTU-RU before spending any more time installing a windows OS. See what its running because its those DLLs I want to play with. Also the CRTU-RU has an either-net port. I'm hoping this is to the Win/DOS PC and not one of the RF cards. It'll speed up development if i can access file system via a NIC.

   O0
 

[msraya]

Ok, Thank You ZL1CVD for your comments..

I work in GPIB programming for a company, and although I don't have extensive experience in the matter, I don't have the time to play with the program inside the unit..
Long ago in the hacking games times, I run softice and cracked several programs in windows98, but nowadays my time is important to me and I have not the time nor patience to approach this issue.

I prefer to use a laptop or rasperry pi or similar board to automatize via GPIB the measures as noise figure, tracking, swr plots, Third order intercept, 1dB compression, and all the measures that interest me. The GPIB support of the unit is very good, extensive, as example you can access files from hard disk through GPIB calls.

However, if you make progress in the hacking I can support you by test or advice. You can transform a dll in a .h file to call from a programing language, but you will have only the entry points of the procedures inside the dll, not the information on parameters or functionality...  So, if you call the dll it can crash, and it will crash every time.

When I receive the new hard disk, i will see the innards of the file system..

I measured THD (as SINAD I cannot measure because my B41 unit has old firmware  ) on my 500MHz receiver with this little program:

*CLS
-> OUTP:STAT RF3
-> SOUR:RFG:FREQ 500 MHz
-> SOUR:RFG:MOD FM
-> SOUR:RFG:MOD:FM:FREQ 1KHZ
-> SOUR:RFG:MOD:FM:DEV 3KHZ
-> SOUR:RFG:LEV -40DBM
-> INIT:RFG;*OPC

-> CONF:AFAN:FILT:WEIG CCI
-> INIT:AFAN;*OPC
-> READ:AFAN?

So, the units can work at the same time.. no problem.. 

Update:  Works with python and VISA with Agilent usb<->gpib adapter, no problem..
I back up the Hard disk without problem. I see the dos app and found the version of the SW as 5.1 but the version of the audio FW is old 3.4.. It can be possible to update the firmware???  I think so.. It is detailed in the service manual as the board firmware must be updated after installation... I am not sure if I mess something..

Advice??

Manuel