Rohde & Schwarz CMU200

[ZL1CVD]

Just listed on eBay 182206586292 "CMU200 comprehensive measurement trace the source / diplexer tracking generator". How does this work? I know about wideband noise source but why the internal CMU200 connection? Does this provide an actual tracking generator taken from CMU200 spectrum analyzer LO output? 

[msraya]

Very interesting Thank You...
There is a output connector of LO1 sweep in the RXTX unit??? There are two free SMB connectors X36 and X35..
I will test it..

I would think the unit samples chunks of the sweep in the A/D and not useful at narrow BW
First IF RX at 1.816115 GHz? Yes.. in the service manual, the LO1 generates inside the RXTX Unit.

Board with amplifier+mixer for 100 US dollars?
If it works It would be Nice...   

I will think about it...
Manuel

[ZL1CVD]

.. and today we have another listing with better price on the tracking generator 252464888662..

[msraya]

I do not need Tracking, I have RIGOL TG...
But interesting.. for people that not have time to homebrew their own..  

Manuel

[Brainbox]

Hi to all readers.
I am new in this discussion and want to share some of my experiences with the CMU200.

Today I received the "CMU200 comprehensive measurement trace the source / diplexer tracking generator".
The unit came with the cables and connectors as shown on Ebay, but no additional information.
Better to say: no info at all.
The PCB has 5 MMICs, a mixer and some other less interesting stuff on board.
Since there is no information available where to find the LO1 signal I had to look for it myself.
The cable for this signal has 1 BNC bulkhead connector for mounting in a free hole in the back, and one straight MMCX connector.
Because the straight type connector makes it impossible to use X35 or X36 (The cover will not close) I was looking for an other free position.
When the metal plates from the RXTX cover are removed some holes shows up which expose some additional MMXC connectors.
Because I have no opportunity to measure this high signal I was looking an other way.
I had one RXTX board from a defective unit I removed the covers to see If I could find the right signal.
As it is the first local oscillator I was looking for the first MMCX connector I could find in the RX path.
Actually I found two two possible connectors after a split in the path.
I took some pictures to show what I mean.
As I don´t want to disassemble the good working CMU200 unnecessary I will take some time to prepare the setup.
When I know more I will let you know.
 

[msraya]

Thank You BrainBox for your review.

I buy also one piece of the kit.. But, I regret that I cannot test it yet...

The kit looks good... It has a double PIN attenuator to get the 0 dBm line right in manual fashion... 
I think it does not connect to the board surface connectors but the board edge connectors..

I not need manual nor information for use it.. It is very simple if you know how work a Spectrum Analyzer..
You can get The OL out from the RXTX board, simply firing the power meter and connect a frequency meter in the right connector until you found the correct frequency and level..

But I advise that this analyzer is only for experienced users.. That's Right 

Regards
Manuel

[bg7tbl]

i designed this board.now there is a new version .
for this board
power:DC 9-12V/0.33A
RF IN:connect to rx/tx board rx lo port.
P2:connect to front panel RF3 ,RF3 setting 1816.115M/-20DBM
IF OUT:TG output 10M-1.2G/0DBM.

any problem send email : bg7tbl@qq.com/BG7TBL@GMAIL.COM

[Brainbox]

Today I hooked up the tracking board to the RXTX unit.
At first I tried the free top MMCX socket X35.
That gave me some result, but only in fragmented parts as can be seen in the first picture.
After that try I decided to remove de side plates from the air ducts to make the internal MMCX sockets available.
Then putting in the connector in the a free socket (the one I had shown on the photo before) I got some better result.
This can be seen in the second picture showing a full span.
Unfortunately the level was not flat in the first 400 MHz or so but shows serious dips in that region.
Even so the picture is not stable but constantly jumping up and down, about once in every second.
Choosing a smaller span gives a much better result, but at low RBW the picture becomes jumpy again.
The last picture shows a 55 MHz lowpass filter.

Now I see they have made a new design with a RF can shielding. 

[Ericmax]

Hello everyone.

Having repaired the PSU and CPU Celeron 650, I bought a Pentium III CPU 933MHz CRTU with an old bios 0.9. (Bug in the time setting)
The DOS system CMU did not want to start. (CPU board incompatibility)
I made a backup of the bios FMR6 Celeron and I Flashed the Pentium FMR6 board.
FMR6 the Celeron and Pentium are the same, the CPU started without problem and the CMU works very well with the FMR6 Pentium 933 Mhz. 
if some have more recent BIOS than the 1.00 I am interested .

For backup and flash, i use awd789.exe . the last version of awdflash don't work with FMR6.

Good evening to all.

[bg7tbl]

reduce the wire connect or adjust the RF3 level can incresa the flat.

[msraya]

Hello All!!

I made test with the item...
I disasemble the CMU200 and then before installation the SA keep working.. no trace in screen.. 
It appears that the TXRX board is not settle in place.. Then It worked again 

So I put out the screening and Put the connector in place, only worked in the place that says Brainbox.
I put the BNC Bulkhead connector in the front plate in the Audio output conector. Then I put the Bulkhead of the audio signal in the rear panel of the unit.. No problems so far..

I put 12V at board and connect the board with little microwave sma cable.. I put 3dB pad after TG generator and adjust to obtain flat response. You can see in the photos...

Then I take a 10.7MHz crystal filter 25KHz BW i cannot remember...
You can measure about 20KHz BW..

It works a treat..    You can compare the trace with a Rigol TG.. The response is practically identical.
At 100 Hz the noise floor of the R&S is about -100 dBm..

The interface of the R&S is poorer than RIGOL, but it works..

P.D: I try to use 1916.2 MHz with the second internal generator to use the first generator at 100MHz with an input mixer and to sweep from 0 to 1.2GHz...  To test 455KHz Ceramic Filters...

BUT, It doesn't work because the BG7TBL design is using a filter post mixer that have a high frequency passband above 10MHz and the signal below 10MHz is greatly attenuated, so it doesn't appear in the screen....
I think also the mixer cannot work at these low frequency..

I would use a two mixer configuration to translate to 0 MHz..

Regards
Manuel

[Brainbox]

The second generator only goes to -60 dBm output power, probably that is too low for the mixer to give sufficient output ?
Indeed the BG7TBL design seems to cuts off from 10 MHz and beneath, but that is the same for the CMU itself.

Nevertheless; with this extension the CMU200 becomes of great value for me.

For frequencies beneath 10 MHz I do use an up-convertor which lift 0-10 MHz by 10 MHz to a useful 10-20 MHz.
Setting the RF generator to 1826.115 MHz in combination with this unit will give you a tracking extension in the 0-10MHz region.

I build the CMU together end mounted the bulkhead at a spare location at the back, the AF positions at the front are already used by the audio extension.
To place the air duct covers back in place I had to drill a hole in one of the plates.

[Ericmax]

Hi all.

small test with FreRes64 V5.25.
RF3 to RF1 and RF3 to RF2.
RF3 set 0dBm in FreRes.

10 to 2700Mhz step 10 Mhz.

RF3 out verified with my URV35 + NRV-Z6
i have same graphic of Rf power.

4dB difference from 10 to 2200 Mhz, may be a small problem on this CMU RF unit.   

[_Wim_]

Hi all.

small test with FreRes64 V5.25.
RF3 to RF1 and RF3 to RF2.
RF3 set 0dBm in FreRes.

10 to 2700Mhz step 10 Mhz.

RF3 out verified with my URV35 + NRV-Z6
i have same graphic of Rf power.

4dB difference from 10 to 2200 Mhz, may be a small problem on this CMU RF unit.   

Do you have the same result if you add some dwell time (to let the generator stabilize)? I can't test on mine right now, but will do when I am back at home.

[richnormand]

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.

Going back to OPs question:

I have read through the entire thread and did not see if the issue had been resolved.

After fixing the PSU and the LCD display ( https://www.eevblog.com/forum/repair/rohde-schwartz-universal-radio-communication-tester-cmu200-psu-issues/  )  the unit passes all diagnostics tests except the internal RF loop and the 1->4 2->4 external loop.

Before going back in the box I wondered if this is a common problem that is well known in the community.

Cheers and thanks.

[w7owc]

I am considering buying this option for my CMU. Is there a practical way to mount this board inside the CMU200. Also how has the newer shielded board worked out?  I want this to sweep different cavity filters 30-1000 MHz? 

[Brainbox]

For me the option works well enough, I have the unshielded first version.
I don't bother about an exact calibrated output because I use it mainly for trimming filters.
Precise levels are not that important.

You can build the option inside the cabinet, I did consider that also.
There is a free 64 pole DIN connector on the main board inside where some supply voltages are available.
Mount the the option board on a adjacent adapter and plug it in the main board.
You can leave the LO cable from the RxTx board inside the cabinet en use  2 SMA > BNC cables to the backpanel to make the 1816.115 MHz and the Input available.

[oh2ftu]

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..    ..

I recently purchased (finally) my own CMU200. It's with FMR6, but PS/2 connectivity in the back.
The hardware options are B12, B21v14, B41, B52v14 and B54v14. Software options include K21-K24, K42, K43 and K45. Firmware version v5.1, v5.22 seems to be most recent.

My plan is to use this to tune radio equipment, but it seems I cannot analyze the audio that comes with the rf signal, is this true? Would the option K29 enable this?
I am able to modulate an audiosignal into the RF output, but cannot analyze it. Drat.

It still seems to be a lot to learn.

[danielg]

The free software FreRes from Rohde & Schwarz allows to make sweep and test for example filters or duplexers.

Manuel

Hi
I have an easy question regarding CMU200 and that is what is the best way to connect GPBI to Win7. I have access to serial port and parallel port (LPT) ?
Can I connect via LPT port or do I need some converter ?
I want to be able to connect FreRes because I hope I can use it to tune some duplexer.

Thanks for alot of useful information 

[msraya]

Hello!!

I want to be able to connect FreRes because I hope I can use it to tune some duplexer.

The LPT port is for printing only. And to transfer files in old MSDOS software.
The serial port works, but You must change secondary addressing for work with RF generator and audio analyzer at the fly. It is made by prefix the command with "1;" You can view it here: https://www.eevblog.com/forum/testgear/rohde-schwarz-crtu-gpib-control/

The CMU200 uses secondary GPIB addressing, so it behaves as three equipment at three GPIB addresses. One for system configuration, other for RF generator and other for Audio analyzer.. you can change it in the setup section.

So the easy connection is by GPIB with multiple addressing to configure. I use an Agilent GPIB to USB converter. I think freeres does not work with serial connection, but I don't know.

My plan is to use this to tune radio equipment, but it seems I cannot analyze the audio that comes with the rf signal, is this true? Would the option K29 enable this?

Yes, I think so.. But I cannot test K29 option. The receiver is SDR I/Q and in theory it has enough power by using a FPGA, so it would demodulate anything if you have the proper software. But it is more easy to use a external demodulator connected to the FI output. I use a Yaesu FT-817 with very good sensibility.

Manuel

[CJay]

I'm away from home now but I'm interested in the K29 option, my CMU200 has a few stickers inside which appear to be option serial numbers, what would K29 give me if it was present? (I have B54 which I believe is required to enable K29)

[oh2ftu]

Oh well. So I bought a second CMU200 (early, K6-2) with a dead (bright white) screen and K29 sticker on the back.
Boots with external display and the price was right.

I managed to fix the display by reseating the display flex, but broke the keyboard. It is now sorted tho!

About analog measurements;
To use as an analog service monitor you will need option K29 (AMPS), B21 signalling unit and B41 (audio analyzer). B54 is not required for AMPS.
Using AMPS will mangle you with a 30kHz stepping, but the offset is adjustable +-15kHz. It will show modulation and you will get demodulated output at the front.
Press the SETUP-button and check your options. The learning curve is quite steep, it's not near as easy to use as Anritsu MT8801B or similar - but you get _most_ of the functionality.

About Freres and R&SCommander. Neither will work over RS232. You'll need GPIB.

[CJay]

That answers one question, I need to obtain a suitable GPIB adapter from somewhere once I've checked which options I have available.

[danielg]

Hello!!

I want to be able to connect FreRes because I hope I can use it to tune some duplexer.

The LPT port is for printing only. And to transfer files in old MSDOS software.
The serial port works, but You must change secondary addressing for work with RF generator and audio analyzer at the fly. It is made by prefix the command with "1;" You can view it here: https://www.eevblog.com/forum/testgear/rohde-schwarz-crtu-gpib-control/

The CMU200 uses secondary GPIB addressing, so it behaves as three equipment at three GPIB addresses. One for system configuration, other for RF generator and other for Audio analyzer.. you can change it in the setup section.

So the easy connection is by GPIB with multiple addressing to configure. I use an Agilent GPIB to USB converter. I think freeres does not work with serial connection, but I don't know.

Thanks msraya for your help
Do you know what options I have to have enabled in CMU200 to communicate with GPBI and use that connecition to tune duplexer ?
Thanks

[msraya]

Danielg:

The generator and power meter both work at the same time in the MSDOS native app.
It is a basic functionality of the equipment, so you not need any special option for it to work.

The program FreRes will use both generator and power meter as same CMU200 unit at the same gpib address..

Manuel