| Products > Test Equipment |
| Video Teardown and Repair of an Agilent E4433B ESG-D Signal Generator |
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| TSL:
Hi Shahriar, Great video and very timely for me. I just picked up a 4432B ESG-D with opts 100,1E5,H99,UND for $700AU :) It has the same fault indicator. I'm just about to embark on a fault finding mission to see if its the same device that failed. FYI you can buy SIRENZA new parts from UTsource here... http://www.utsource.net/ic-datasheet/SHF-0189-1906844.html regards Tim |
| TSL:
Hi all, Just finished repairing my 4432 and guess what ? It was the same fault that Shahriar had in his, that FET had failed. Mine thinks its a 25ohm resistor! Not having any on hand and thinking about the 2 week delay to get some from UTsource I rummaged around in my box of MMIC's and found a Minicircuits GALI-84+. The GALI-84+ has the same package and similar IP specs as the FET. Fitting it was a breeze and now the generator is fully working. Testing it against my Agilent 8935 test set shows its output and modulations within spec. :) regards Tim |
| G0HZU:
Sorry for the late reply but I found this thread again on google and I have a few comments about the use of the GALI 84. If you look closely at the original Agilent PCB layout/circuit with the SHF0189 there appears to be negative feedback fitted in the form of an RC circuit. It's there for various reasons and if you look back at my earlier post in this thread I also used similar feedback when I was designing with the SHF0189 many years ago. This feedback improves the SHF0189 matching (because it isn't really a 50R gain block MMIC) and also it improves the stability and also it flattens the gain across a huge bandwidth. This is very desirable for a wideband sig gen path. Without the feedback the gain will be very high at the low range of this amp (eg down at 250MHz) and this will mean the system ALC will have to work over a wider range depending on the sig gen frequency and the amp will be run harder here too. You might well get away with using the GALI 84 but you must be losing a fair bit of ALC margin at low frequencies because it has lots of excess gain at low frequencies. So there is technical risk here. IMO it's best to try finding the original part or a better equivalent that runs closer to the 8V? drain voltage of the SHF0189. The GALI 84 looks like a reasonable device to used for a quick/dirty repair but I think these sig gens deserve to be repaired bettter than this. But that's just my opinion :) Note that I don't know how well Shahriar got on with the free SHF0189 samples I sent to his office at Bell because he didn't respond to me after I sent them. They could have been lost in the post for all I know... |
| TSL:
G'Day, Yes - you do have a point - and personally I'd have liked to replace it with original parts too, but I wanted it for immediate work and I've not returned to the point of making it right. I should put its resolution on to the list of things to do ! :) |
| drago:
This signal generator deserves a proper repair. Explaining what is going on around SHF0189 is also a good material for a follow up video. |
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