looking for oscilloscope recomendations

[PfeifferElectronics]

I'm in the market for a new scope too. My favorite candidate is the DS1052E 50 MHz Digital Oscilloscope | Rigol - Beyond Measure

However, the max input voltage is 300V RMS. My question is this high enough? If I use the standard 10:1 probe can I scope my 500V filter caps?

Thanks

[Tom Phillips]

...If I use the standard 10:1 probe can I scope my 500V filter caps?

I say that would depend.
There is lots of discussion about probing HV sections of tube amps at http://music-electronics-forum.com/t31492/. Check out the interesting point made by Dave H in post #9 of that thread and the ensuing discussion. I added my comments in post #21.
Regards,
Tom

[Cygnus X1]

I'm still new at using scopes but I generally stay away from HT at all with the probe.
Using it for signal tracing only at this point.

About the military VTVM 410B (or C).
Any chance of finding the probes?
Scrap it?

[Kazooman]

That's what the 10X is all about. Here are two pictures of my Rigol scope measuring the DC output fro the bridge rectifier in a 1970's Klempt Echolette Tape Echo. The trace doesn't show on the first pic, so I took a close up. We are well over 300 volts here. Note the wrap of blue painter's tape on the probe. The 1X - 10X switch moves very easily and it is right where you would move it if you are not careful. Mine is "locked" in the 10X position. I have the second probe if I need to go to 1X. Do not exceed the voltage rating of the probe itself and you will be OK. For extra personal safety (not protecting the scope) you can clip on the leads and then power up the amp.

[Tom Phillips]

...About the military VTVM 410B (or C).
Any chance of finding the probes?...

I have seen them discussed in HP discussion groups. Also remember people talking about refurbishing the probe sets and making replacements. However, that can get relatively expensive and is usually only worth it to HP collectors. Note that the AC probe is a very special sophisticated design that actually has a small vacuum tube in the probe head. You can get info from the Op manual posted at http://www.hparchive.com/Manuals/HP-...prefix-024.pdf
Tom

[PfeifferElectronics]

Thanks Tom. After reading the other posts, it appears that I can measure DC voltage with DC coupled scope. But what I'm really after is ripple/ac on B+. So to do this I would need a high voltage probe. However, the one for my oscilloscope costs as much as the scope! Could I use one like this? Wholesale P4060 100:1 pressure the 2KV 60MHz Oscilloscope High Voltage Probes Probes, Free shipping, $25.13-35.23/Piece | DHgate

or this?

P4100 100:1 100MHz Pressure 2KV Oscilloscope High Voltage Probe 16278-in Instrument Parts & Accessories from Industry & Business on Aliexpress.com

[Tom Phillips]

Thanks Tom. After reading the other posts, it appears that I can measure DC voltage with DC coupled scope. But what I'm really after is ripple/ac on B+. So to do this I would need a high voltage probe. However, the one for my oscilloscope costs as much as the scope! Could I use one like this? Wholesale P4060 100:1 pressure the 2KV 60MHz Oscilloscope High Voltage Probes Probes, Free shipping, $25.13-35.23/Piece | DHgate

or this?

P4100 100:1 100MHz Pressure 2KV Oscilloscope High Voltage Probe 16278-in Instrument Parts & Accessories from Industry & Business on Aliexpress.com

Probably. I use older Tektronix probes which I have picked up in the same price range. I like that I can download good info and the specifications are trustworthy & conservative.
"...pressure the 2KV 60MHz Oscilloscope...

[PfeifferElectronics]

Tom, do you have some model numbers that you use? I just don't want to fry my new oscilloscope. I'm pretty sure that is what I did to my Tektronix 475 scope. I had it on AC coupling using a 10X probe measuring 500VDC. Plus it was an old scope I picked up for $200, so not too big of a loss. That said, I can't afford to blow up test equipment anymore!
Thanks

[Tom Phillips]

Tom, do you have some model numbers that you use?...

For 100X I have a Tek P6007 and a Tek P6009.

[km6xz]

The fastest killer of probes and instrument front ends is not over their DC max input voltage, it is creating parasitic oscillations that can be very high RF voltage. That happens when probing around and as you remove the probe from a high z test point, as the probe is fractions of millimeters away, the capacitance generates an oscillation and actually creates a little arc and the tell tale ozone smell. It can create a thousand RF volts instantly. That is a good reason to avoid using digital scopes and Chinese probes in live tube gear. If you want to be save, turn off the HV and securely attach the probe and then energize the circuit. De-energize it before removing the probe. You don't have so much of that problem with things like your 475 Tek, which will outlast a number of burned up light weight digital unit.
Get Tektronix probes if you are going to be testing live circuits, the cheap Chinese probes won't last nor are they reliable.

The 410C AC probe is hard to find but they can be found. There are a number of people who rebuild them as a retirement business.
I do not understand the desire to skimp on the the most important physical asset a shop has. A couple hundred dollars each for some lab quality instruments industrial surplus is the best investment for increasing efficiency, and reliability of the repairs. Not having accurate instruments which give readings based on known standard parameters leads to guess work and shotgunning, both of which lower efficiency and increases costs to customers needlessly.
As it is, amp repair is one of the very lowest cost of entry for a small business there is. Spending a few thousands on good test gear is quite a reasonable long term investment with a short payback period. Just the improvement in efficiency and lower false diagnosis will pay for the better test instruments very quickly.

[Joe L]

The new digital scopes have a lot of great features. However, at work we have 30 year old Tek scopes that have been riding in vans for all of their life and still work like new.

In my opinion, the best scope for our purpose is the Tektronix 2247A. It has a built in voltmeter and frequency counter. Most important, it has a 1-touch setup button that saves a heck of a lot of time. It is also fantastic for someone who has never used a scope.

I also have a Tektronix 2465 which is a newer scope, but no vm, freq counter or 1-touch. It is still a nice scope but not nearly as convenient to use.

I was patient and got the 2465 for $170/free shipping and the 2247A for $110/free shipping off of Ebay. Both scopes work flawlessly.

If you get a scope,you need a signal generator. I bought a Tektronix CFG250 for $90 off of Ebay. Works flawlessly.

[Tbone123]

CIE Bookstore has some affordable scopes.
Oscilloscopes