Tek scope question

I finally got around to buying a scope yesterday (Tek 465B), and in looking thru the specs in the manual, it states that the max input voltage (for either DC or AC coupled) is 250Vp plus the peak AC voltage, or 500Vpp.

I intend to use this in some upgrades to my tube preamp; I would like to take a look at AC ripple off the filter caps in the PS sections, one portion which is at 425Vdc, the other which is at 250-260Vdc or thereabouts. I know the second one should be OK, but what about the first?

When I was a tech, I didn't worry much about it, since it wasn't my scope . Now that it is, uhhh...

Thanks,

Chris

(remove the obvious to reply)

Reply to
Chris Young
Loading thread data ...

As long as there is no ground loop (chassis of the preamp and chassis of the scope), then the ground of a X10 probe is connected to the ground of the PS (presume at chassis ground), and the probe tip goes to the monitor point. The probe rating, as i remember, is 500V; since it is dividing by 10, that gives a maximum of 50V to the signal input connector - which has its own rating. There are special high voltage probes for monitoring signals in the KV region, which may be useful on rare occasion.

Reply to
Robert Baer

My 465B book interprets it differently, it say 250V for the TOTAL of the DC plus the peak AC, or 500 v P-P below 1kHz.

Don't be cheap, buy yourself some 10X probes and then all will be legal. You can get decent probes new for about $35. Look at the Velleman or Pomona or Probemaster probes, a step up would be PMK. If you work on tube stuff you may want to consider getting a few 100X probes as well. The minimum sensitivity of the 465B (without probes) is 5V/division, so, without probes, you can display only 40 volts P-P on the screen. That is only about 12 VRMS, and you may well exceed that in some preamp and many power supply situations.

However, for audio frequency work, you could just hook up an external series capacitor to block the DC component. Likewise, for low frequency work, you could improvise a 10X probe by putting a 9M resistor in series with the input. Don't expect much accuracy above 5 kHz or so, however.

Reply to
BFoelsch

Hi,

Thanks for the resp> My 465B book interprets it differently, it say 250V for the TOTAL of the DC

Reply to
Chris Young

If you have x10 probes, the probe is likely the limiting factor. There is a website somewhere which has a table of the tech details of all Tek probes. Unfortenately I lost the URL, I seem to recall it was dedicated to old Tek equipment.

Mat Nieuwenhoven

Reply to
Mat Nieuwenhoven

Not the site I was looking for but:

formatting link
and
formatting link

Mat Nieuwenhoven

Reply to
Mat Nieuwenhoven

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.