| Electronics > Repair |
| E4407B Tracking Generator Repair |
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| analogRF:
--- Quote from: smgvbest on September 27, 2020, 06:37:45 pm ---So when you trace the correct PIN its pretty easy to find. See attached (Attachment Link) --- End quote --- Still I cannot find what that sot-23 package MC-0 is but it appears to be (probably) a two diode package and since pins 1&2 are connected it is a back-to-back connected diode which connects the TUNE voltage (0 to 12V) to that VCO it all makes sense I believe... the schematic of this thing is pretty much all clear now. you need a probing strategy to check various points during fail conditions. But it is pretty clear now what you should expect at different points I see most people who have had TG issues in these ESA series it usually has been the IGG5 hybrid .... |
| smgvbest:
So not a exact replacement if this is what wrong. I found this the attached. The pinout is very close, mainly NC pins on the side that do not appear on the device in the unit. I will pull out the Rigol tomorrow and probe before and after that component with the TG set to zero span and 50Mhz. at -9dB i do not get the Source Unlevel, at -10dB I do. so the output will be well withing the range of the Rigol SA, I can also probe the 600Mhz in and the VCO. I will get that done soon with a poor mans rf probe. Also found this on Keysights site https://www.keysight.com/en/pc-1748995/millimeter-wave-and-microwave-gaas-limiters?nid=-33897.0&cc=US&lc=eng @analogRF you mentioned you where going to post a pic of your RF probe, where you able to find the pic? |
| analogRF:
--- Quote from: smgvbest on September 28, 2020, 03:13:02 am ---So not a exact replacement if this is what wrong. I found this the attached. The pinout is very close, mainly NC pins on the side that do not appear on the device in the unit. I will pull out the Rigol tomorrow and probe before and after that component with the TG set to zero span and 50Mhz. at -9dB i do not get the Source Unlevel, at -10dB I do. so the output will be well withing the range of the Rigol SA, I can also probe the 600Mhz in and the VCO. I will get that done soon with a poor mans rf probe. --- End quote --- this chip does not have any peak detector output for level control loop. the one in your TG does RPP and has level detector. it's good strategy to probe before and after that IGG5 when the error appears and when it doesn't also at that point I suggest checking the control voltage that goes to the HMC346 variable attenuator and see if it is changing or not and also check the the PWR_LVL signal that comes from A2A1 to the connector pin 8 and also the ALC_MON at pin 6. these are all DC so easy to probe and document what you see |
| smgvbest:
--- Quote from: analogRF on September 28, 2020, 03:21:21 am ---this chip does not have any peak detector output for level control loop. the one in your TG does RPP and has level detector. it's good strategy to probe before and after that IGG5 when the error appears and when it doesn't also at that point I suggest checking the control voltage that goes to the HMC346 variable attenuator and see if it is changing or not and also check the the PWR_LVL signal that comes from A2A1 to the connector pin 8 and also the ALC_MON at pin 6. these are all DC so easy to probe and document what you see --- End quote --- Set for 50Mhz Zero Span, -10dB was Level, 3dB was unlevel. reading at Top for Level, bottom was unlevel see photo Also VCO? 782.5Mhz see photo |
| analogRF:
1-what are these numbers? what does -57 mean? 2-what did you measure them with? I mean was it scope or a spectrum analyzer? 3-the most important thing is what probe did you use? 4-for VCO this is very strange! but we dont know what that pin is so please measure the VCO at the RF input to the mixer (pin 3) and also more importantly measure the IF output you can measure at pin 2 of mixer but better is to measure at the output of the big filter which is the input pin of the blue "LF3" filter |
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