> Mike, > That PS is a most curious problem. For reduced leakage fields from > 60Hz transformers, it was common to have a wide copper strap > wrapped around the transformer in the same orientation as the > windings.
> This strap was the full width of the winding bobbin, but formed a > shorted turn on the outside of the transformer to reduce, or > eliminate leakage flux. > Does your tranformer have this shorted turn on it & is it still > shorted? > Any chance your line setting is 100V? This would certainly run the > transformer towards saturation. Can you power that unit from a > Variac & set the voltage down enough to see the external fields > slack off? > H-P had a rather conservative limit on external fields at power > line frequeny & this was always verified during environmental > testing, so I'm quite surprised you're seeing this issue. I think > something is broken. > Pete Rawson Hi Pete, I remember the copper strap from my younger days repairing tv sets for my neighbors. That was a long time ago:) The power transformer on the 53310A is huge - way bigger than it needs to be for the load. But I don't recall seeing the copper strap. As I recall, all four sides of the transformer were visible. I thought that was quite odd as I was expecting to see the copper strap. Part of the problem is the TEK 2467B is extremely sensitive to magnetic fields. The crt has a channel multiplier to allow viewing single-shot events at 1ns/div like the TEK 7104. So the deflection sensitivity is much higher than normal. The problem is definitely due to stray magnetic fields. The only way to have the two instruments turned on at the same time is to put one on a different bench. That is a bit awkward when you need to run back and forth to adjust the controls. The line voltage is 125V, so that's not the problem. Both instruments are pristine inside and seem to be working fine. The 2467B doesn't seem to be affected by any other instrument except the 53310A. Another small point. I mounted a fluorescent light under the top shelf where the TEK 2467B's sit. It turns out the small ballast inductor for the fluorescent light also delivers enough stray field to demolish the 2467B. I solved the problem temporarily by unscrewing the ballast and letting it hang down about 6 inches, supported by the leads. It's been like that for a long time. I was just looking at it now, and remembered that I promised myself I would mount it properly as soon as I had some time. So I think the 53310A is OK - maybe just a bit stronger field than usual. And the TEK is indispensable, so I just have to find ways to keep the stray fields away from the scope. BTW, both scopes show the same problem, so it's likely intrinsic to the design. Mike _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
