Products > Test Equipment
Rohde & Schwarz CMU200
_Wim_:
--- Quote from: msraya on May 18, 2016, 11:02:13 am ---So if the equipment does not have DC block capacitor, as is the norm, you will have to supply one.
--- End quote ---
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_:
--- Quote from: ZL1CVD on May 18, 2016, 02:33:39 pm ---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?
--- End quote ---
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 :-DD 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
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