Advantest R3477 - Signal Analyzer - Wiring

[SP4020]

Hello and welcome to everybody reading this post. I have got an used R3477 Signal Analyzer from Advantest over an auction. It seems to me that it was previously not used as a spectrum analyzer and its configuration is different to what I have seen here before on the forum. The equipment displays the spectrum noise floor only and no signal is indicated when the calibration signal or an external signal is applied to the RF IN. During boot a window named Signal Generator pops up, but it's not possible to interact with it. The unit passes the selftest but is not able to calibrate itself due to "calibration level too low" error.

I have screwed off the cover and had a look into it. The main "RF-Input" is connected via some inline filters and a frequency doubler/amplifier to the "1STLOTG". Please see attached the pictures of the bottom and left compartments. The yellow arrows show the path from the RF-IN connector. Blue, green, red and purple connectors are left open. Normally I would have expected some cables running there. The output of the doubler/amplifier "2F" is on the side of the RF-IN.

Seeing this wiring/configuration can anybody confirm that the setup is wrong? If so, any ideas of what this unit was used before? Finally I would appreciate any input on how to set up a working configuration and get it running again. Thank you very much for your ideas, thoughts and comments about it.

[DaJMasta]

One of the posts on the first page has a pic of one https://www.eevblog.com/forum/testgear/advantest-r3477-9khz-to-13ghz-spectrum-analyzer/

Don't have a pic of that section of mine and just closed it up.... 


Are there any custom labels on the back, maybe that could give you a hint.  I've seen a customized analyzer from a different series that had some non-standard outputs labeled in the aux ports on the back and it seems like Advantest will customize as needed for customers wiling to shell out for it.

[nctnico]

If this is a custom job then it looks a bit shoddy to me. It seems there is a different module in there compared to mine .

[SP4020]

On the rear side one of the BNC connectors, which according to the manual should be "421M IF OUT", has a custom handwritten label "200M IN".

Additionally I found 3 versions of the PAX-Software on the SD-Card. The autostart file has been changed over time and the following comments were added:

****  R3477 Special Function with R3681 Synthe Module
****  Additional AD data Readout

[DaJMasta]

Hmm, interesting.  May be worth finding a similar picture of someone with an r3681 series instrument to see how the different synthesizer plugs into things there.

Since the 200MHz input is kindof an odd one..... could that be something not generated by the r3681 synthesizer board?  If so maybe it's an external input needed to run properly?  I wouldn't really expect it... but if you have the means of feeding a 200MHz signal into that input, it may be worth trying to see if it clears up the error.  Perhaps whatever benefit going to the upgraded synthesizer gave (phase noise, sweep speed?) meant they had to get the 200MHz IF from an external source.  Though I'd expect that to be locked to other stuff..... so I maybe there's not a big chance it relies on the external input.  I guess in either case, since it was originally specified as an output, maybe check to see where it connects internally before applying a signal.


If you haven't done so already, maybe just mapping out the layout you have can help decipher it - seeing a sort of flow chart for the system could clear up how it's actually operating or what could be missing easier.

[SP4020]

I have checked the custom labeled "200M IN" connection. The connection leads into the left compartment but the cable isn't connected to anything.

Please see below a map of the wiring. I assume the main missing connections are located in Module_5 and Module_6. Compared to mine, Nctnico's picture shows a completely different layout in that section.

At least I have identifed the location of the "50MHz CAL Out" signal, which is working and confirmed with another spectrum analyzer. I have marked its location in the picture below.

[nctnico]

I'm afraid that the parts for the spectrum analyser are missing. If I compare my pictures with yours then I'm missing the input attenuator, a band filter and the wires which connect the first mixer to the RF block.

[suj]

Some time ago I found a note where simplified block diagrams R3681 are placed. I copied it to my server:
http://www.procontrol.home.pl/pawel/R3681/pdf_Technote_R3671_R3681_21_17_jp.pdf
It can be translated from Japanese, texts can be copied. Maybe it will be helpful.
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