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All, thanks for the replies. Does an RF signal gen such as say 8340B generally have poor source impedance? Has someone examined this before? I am wondering if the problem of mismatch and standing

Dave B, where can I find the terminology of "slugging" a control loop? First I've ever heard the term and I'm intrigued. Thanks, Dave W ________________________________ Sent: Monday, September 2, 2024

Q4 emitter is close to 0V anyway during use.? It is grounded by R11 0.27 Ohms, as the output current sense resistor.? Q4's base should never be +ve vs 0V by much more than a Volt or so, ever.? If

Bruce, There's clearly a fault here as there is no signal present to adjust. I've set out more complete info on this issue in the thread entitled "8566B Can't Calibrate" if you have the time to read

Q4 collector is around 16v still. C9 looks OK on the surface. R49 is a little hard to test but my old fluke says somewhere in the neighborhood of .02 to .04 ohm. No heat but signs of past heat, faded

Bill, What is the voltage at the collector of Q4? Also if you have a 10 A ammeter remove F4 and measure the current. I sounds like there is a short somewhere. Keep the fuse in the circuit to protect

After a few second warmup I get 1v at q4 emitter [email protected]> wrote:

Yep all purple/white disconnected on the left. Currently almost no voltage at output of q4 emitter, -0.02. It's also getting hot. Wonder if it's toast bc I lost my -2.5v since. [email protected]>

Bill. You are making progress! Now we have to find out where the -12.6 current is going. Especially since the driver is getting hot. It is funny that the current limiter is showing 0V. I think some

They almost certainly did specify a Schottky with an appropriate leakage spec. The problem wasn't the spec -- it was that the leakage increased beyond spec over time. More things can go wrong with the

That's what they say - but why go to? a 'regular' diode?? And go from 0.3 to 0.7 fwd drop. A better replacement would be a schottky with a low leakage spec. However, some power down circuits do get

Thanks, Bruce. I'll have some time free later today to try this suggestion of yours. We'll see if it reveals anything in due course...

On Sun, Sep 1, 2024 at 09:36 PM, pianovt wrote: > > Vladan, that does make good sense and would certainly be worth trying. I > just want to try any other possibilities first, as I don't have the time

CR123 are available in 3.0V and 3.6V The 3.0V version is common in camera shops.

I need to do an o-ring replacement of an 8497K attenuator with N connectors and a Viking control cable. I have done this on an attenuator with SMA connectors and an IDC ribbon socket. Disassembly on

You should probably do the following: 0) Connect CAL OUTPUT signal to RF input. 1) Press GREEN BUTTON, then RECALL followed by 8.? Adjust the amplitude to -10db using AMPLITUDE ADJUST next to the RF

AWolf provides a pretty nice description, (with cautions) about what is going on on the 3474a Bus. A goofy short can render the Sram loss and ... demise. He describes an Fram mod, deleting the need

Also See: https://k6jca.blogspot.com/2017/12/save-and-restore-hp-3478a-calibration.html using Matlab by Jeff & Dick Benson rick

Steve, See: https://tomverbeure.github.io/2022/12/02/HP3478A-Multimeter-Calibration-Data-Backup-and-Battery-Replacement.html

Negative. It is indeed directly due to Schottky diode degradation, as stated in the Hp Service Bulletin 4274a-12?? ,? referenced above: " Improvement for Memory Backup Battery" ... " Symptom and