Scoping small current pulses with Tektronix TM500 series?

snipped-for-privacy@hotmail.com wrote in news: snipped-for-privacy@i3g2000cwc.googlegroups.com:

Make/insert a small 10 turn wire loop to place the A6302 probe around;that multiplies the current sensitivity by 10. You may not disturb the signal enough to matter,it depends on your circuit.

IIRC,the highest sensitivity of the AM503/A6302 is 1 ma/div.

Of course,you can also change the display scope's Volts/div setting to magnify your resolution.(there are limits,though) And AC couple the scope,or use one with an adjustable DC offset,like a

IIRC,that's set at 50mv/div,50ohm inputZ. AM503 system BW is 50 Mhz,IIRC.

BTW,I used to repair/calibrate AM503 systems at TEK-Orlando. (before they shut all the field offices down)

"Jim Yanik" a écrit dans le message de news:Xns9815D1ACF393Ajyanikkuanet@129.250.170.83...

circuit.

Glad you said that. I just got hold of an AM503 that had been severely "adjusted" to the point its sensitivity was off by more than 25%. I went through all the cal procedure, but got a bit confused by the 'adjust until getting good results' for the HF compensation resistors and cap.

Do you have any good hint about this?

Jim,

Please excuse me for taking this opportunity to consult you.

I have a copuple of AM503's with attenuator issues. The contact fingers are loose efter the nylon? fasteners have broken/cracked.

Is this a common problem or am I just unlucky? What is the best way to fix this?

Thanks, Anders J

"Jim Yanik" skrev i meddelandet news:Xns9815D1ACF393Ajyanikkuanet@129.250.170.83...

circuit.

"Anders Johansson" wrote in news:2ahBg.12055$ snipped-for-privacy@newsb.telia.net:

I believe you are talking about TEK's HF cam switch contacts. Yes,with age,the white plastic degrades and the gold-plated contact fingers fall off the spring portion. You will have to find some other TEK instrument with intact contacts you can cannabalize for your AM503. TEK used to offer a complete kit for this,but it's long out of production/stock. The new contacts were bolted down using 2-56 bolts and nuts,IIRC. Begin cannabalization by removing the solder at the rivet end,and use a small 1/8" drill to remove the rivet by reaming off the flared end of the rivet.then push out the rivet,the contact may come right along with it. I believe the contacts are used on both sides of the PCB,too.

I suppose you could try wicking some thin cyanoacrylate glue into the loose contact where the plastic holds the contact fingers,but don't get any on the fingers!! Maybe run the superglue down a needle or fine wire to where you want it.I've not tried that,though.

"Fred Bartoli" wrote in news:44d4d86a$0$13532$ snipped-for-privacy@news.free.fr:

You have to watch for metal film gain resistors changing value.Then you end up at the limits for gain pots,which may affect freq.comp.

Well,the AM503 amplifier can be "pre-adjusted" without the A6302 probe by driving a signal into the connector,IIRC,there was instructions on how to do this in the manual,and how to make the adapter. One thing is that the A6302 probe is sensitive to being dropped and that can crack the ferrite head or damage the Hall device and you'll never get it to compensate properly.

also,some of those tiny adjustable caps can have the slot break loose from the rotor disc and it looks tlike they're adjusting,but nothing changes,because the disc itself is stuck and not turning with the metal 'slot'.They can also develop a black silver oxide underneath them and that insulates the rotor from the metal stud,making it effectively open.

BTW,TEGAM bought the TM500 line from TEK,and were providing parts and service for AM503. I'm not sure if this is still true though.