开云体育

Years back I had a problem in my 8660 where I had 60 Hz sidebands on the CW output that exceeded spec.? After extended troubleshooting and consultations with the (at the time) Yahoo group it came out that the problem was not electrical in the power supply itself but related to the transformer which was creating an external magnetic field which was inducing current into the instrument frame rear section which formed a pickup loop and this 60 Hz ground potential shift was getting into various electronics.? Mechanically breaking the loop temporarily would eliminate the output noise and I considered a mechanical solution involving a machined FR4 piece to replace a small aluminum section but eventually was able to find a replacement transformer which solved the problem.? It didn't eliminate the problem but attenuated the 60 Hz to where it was acceptable and within spec.

The new transformer was audibly quieter as well.? IIRC it was the 400 Hz capable one, as was the replacement.? I believe most of the instruments available at the time were military surplus.

I disassembled the old transformer with guidance from at least one person from old HP who was intimately involved with this generator and even posted photos but there was no obvious faults found such as an unsoldered or cracked copper sheet shield.

One conclusion was that it was entirely possible that some instruments left the factory out of spec due to issues in their transformers.

I still have the instrument and it still works but needs alignment and the low frequency plug-in needs repair at some point.? Much of the alignment can be done without extenders but some adjustments cannot be done without and that's kept me from working on it in favor of other projects.? Perhaps I can borrow a set from someone at some point.

Peter