Rohde & Schwarz CMU200

[_Wim_]

For measuring the frequency responce, you also can use the FreRes software (https://www.rohde-schwarz.com/uk/applications/freres-program-for-frequency-response-measurements-application-note_56280-15551.html) where the generator and analyser are configured for as many frequency points as you want. You can get a very high resolution read-out, but that takes a long time. But still, very usefull.

[usagi]

i love my cmu200, the only downsides are no preamplifier option, and it only goes down to 10mhz.

it has a great signal generator, and with freeres i even have a poor man's tracking generator.

for what i paid for it, it's a phenomenal value.

[CJay]

i love my cmu200, the only downsides are no preamplifier option, and it only goes down to 10mhz.

it has a great signal generator, and with freeres i even have a poor man's tracking generator.

for what i paid for it, it's a phenomenal value.

I'm rather keen on mine too, I've been tinkering with using one of the RF generator outputs as a LO for an external ADE-1 mixer, yet to quantify results but it seems to work.

I am having problems getting results from FreeRes though, I'd be grateful for any tips on configuration of the CMU and PC?

[Brainbox]

I have both the tracking generator and the noise generator.
From those I prefer the tracking generator for its broader band.
The noise generator only have a satisfaction output in a small band.
Higher the bandwidth  decrease the output level ans also the resolution.
But it can be useful for preselection purpose.
FreRes also is a great solution but requires the use of a external PC.

[Octane]

Hi,

I'm looking into buying a CMU200. But I'd like to know a few things.
Can the built in generator do FM, AM, or any other analog modulation types?
Can any of the analog modulation types be analyzed/demodulates?

I tried to find general info on the CMU200, but I could only find documentation on for example how to do GSM measurements.
No general manual or any other information.

Thanks,
Michael

[Brainbox]

Yes it can do most types of modulation for measuring purposes.
Do a search at Google for the user manual and service manual, you will find all the specs You need.

[Octane]

Thanks Brainbox,

That's what I wanted to know. And yes I googled for the manuals, but I was not lucky yet. I'll keep trying!

BR,
Michael

[usagi]

Can the built in generator do FM, AM, or any other analog modulation types?

yes, it can do FM, AM, SSB, DSB, CW

Can any of the analog modulation types be analyzed/demodulates?

yes, but you have to get a cmu200 with the correct options.

[ps]

One question concerning RF ports 1 and 2: these can be input and output at the same time.

Is there a directional coupler present, i.e if I use the signal generator to drive an antenna, do I measure the returned power (S11)?  Or does it just measure the voltage and calculates some kind of equivalent power assuming a 50 Ohm load?

This is not clear from the block diagram in the service manual.


Thank you, best regards
Patrick

[Octane]

As far as I understand this it is either/or not and. There is no directional coupler inside. Please correct me if I'm wrong.

Michael

[usagi]

cmu200 has no directional coupler.

took me a while to figure out how to do RL with freeres. if i remember you have to use RF3 out with RF1 in.

[Ringmodulator]

Hi,

for my understanding, the CMU-B95 ADDITIONAL RF GENERATOR limits the max RF input to 2W.

 Is it sufficient to remove this unit, to be able to use the full RF input of 50W, or do I need some kind of "jumper cable" to bridge the connections of the removed board?

Chris

[RF_fanatic]

Yes, use AMPS option of the CMU and the audio output which can be attached to any audio input of a normal amplifier and you can use it as tuner (fm demodulated)

[cmu2017]

Hi,

I would place my tracing generator into the CMU. So does anyone know if there is somewhere 12v inside available? And it would be nice if this 12v can be switch on and off by one of the (function) keys on the front.

Does anyone know if this is possible?

[Qw3rtzuiop]

There are two 12V rails inside. One is always present (12V standy). The other rail is available on power up. Afaik there is no switchable rail.

[cmu2017]

Too bad that there is no switchable 12v. Have you maybe a photo or something else to see where I can find that 12v?

[Qw3rtzuiop]

You can take a look at the service manual. There are the connector descriptions. The 12V should be present at almost any of the big connectors at the main pcb.

Edit:
Here is the spare parts list with the connector descriptions:
http://www3.rohde-schwarz.com/www/FileTranCS.nsf/4073a08b63359686c1256ae6002f8239/0b37697a081fa22ec1257834002005ed/$FILE/Shb-inst_Documents.pdf
Its not in the service manual.

[cmu2017]

Thanks, I found it.

[cmu2017]

Does anyone have the print design of the motherboard? I want to cut some small part of the corner. So I can place a new rivet nut for the leg. But I need to be sure there is no circuit on that place. (See image)

[cmu2017]

I’m using the cmu200 now for a while and I have a few questions about it which I couldn’t find on the manual.

- Is it possible to set a ref -> pk  to a negative peak
- Can I change the power measure form dbm to watt
- Is it possible to make a print screen save it a usb stick

[PartialDischarge]

- Is it possible to make a print screen save it a usb stick

In my CRTU I bought a PCMCIA to SD adapter to make screen dumps, but all attempts with different card sizes have been unsuccessful, although someone told me it worked in his unit.

[capt bullshot]

In my CRTU I bought a PCMCIA to SD adapter to make screen dumps, but all attempts with different card sizes have been unsuccessful, although someone told me it worked in his unit.

I did successfully install additional FW modules on my CMU200 (old CPU board w/o USB) using a PCMCIA to CF adaptor.
Never investigated how to make screenshots onto this CF card, would be interesting to get some hints ...
What I'm really looking for would be some simple linux software that connects via RS232 / GPIB to the CMU200 and takes the screenshot by running a simple binary on the PC - hardcore command line style, no clickety GUI.

[cmu2017]

In my CRTU I bought a PCMCIA to SD adapter to make screen dumps, but all attempts with different card sizes have been unsuccessful, although someone told me it worked in his unit.

What button’s do you use to make screencopy and how get it to the PCMCIA card? And are running for this on dos or windows. I’m using the dos modus.

[PartialDischarge]

What button’s do you use to make screencopy and how get it to the PCMCIA card?

PRINT IIRC, there was an option to change the destination of the print somewhere, either to the HDD or the external memory through pcmcia

[cmu2017]

Ok, thanks, I'm going to try this.