Got a free Tektronix 2445A 150MHz 4 channel scope

[Willabe]

A friend just gave me a Tektronix 2445A 150MHz 4 channel scope with a high voltage probe. Looks to be in good shape. 

Is this a good scope for tube amps? Anybody familiar with this scope?

[pompeiisneaks]

From what I understand any scope in the 50MHz range is fine.  I just bought a Rigol DS1054Z because it gets rave reviews for having 4 channels and 50MHz.  The audio range of most guitar amps is like 10Hz to maybe 20kHz.  So 50MHz is well within range. 

~Phil

[vibrolax]

I'm not familiar with that particular scope, but it is more than perfect (as long as you have a 10x probe) for working on any kind of audio gear.  You received a great gift.  My everyday scope is a 15 MHz Leader LBO-514, though I do have a Tektronix 556 (100 lbs, 44 tubes, 800W).  Oh, here's a picture of one stack of my test equipment when I was moving it earlier this year.

[Willabe]

Nice looking stack of test gear. 

Yes it came with a 10x probe.

A friend from church is coming over this week to show me how to use it.
 

[pompeiisneaks]

I was under the impression that a 10x scope probes can't take over 300v and guitar amps regularly go up to 500 or 600 in some cases.  I bought a few 100x scope probes so that I can go higher.  Anyone want to confirm that for me?

[vibrolax]

I was under the impression that a 10x scope probes can't take over 300v and guitar amps regularly go up to 500 or 600 in some cases.  I bought a few 100x scope probes so that I can go higher.  Anyone want to confirm that for me?

I don't know for a fact. My lbo-514a label on the bnc input says 600V max.  My tek p6103 says it's good to 500v.   The voltage ratings for your probes should be on the data sheet.

[sluckey]

The 2445 Max input voltage is 400V (dc + peak ac) or 800 V pp ac @ 10KHz or less.

Here's the operators instruction manual. You can probably find a service manual also.

     http://www.mit.edu/~jhawk/tek2445.pdf

[PRR]

Voltage rating on probes depends more on the caps they use than the X-factor.

Since 'scopes don't need more than a Volt to get a full picture, 100X probes may be useful for a 'scope which has little turn-down for large inputs.

Note that the OT plate leads of a 400V DC amp will kick to 700V-800V.

In many practical cases, you do not need a precision probe. 10Meg and 100K gives 100X reduction, stands high voltage, and uncompensated bandwidth is beyond the audio band.

IMHO 1MHz is more than ample for 99.44% of guitar-amp work. 100KHz is often fine. I have used a 19KHz 'scope and learned stuff. With the transistorization of 'scopes, you can't hardly find anything under 5MHz. Bandwidth is a non-feature. Easy controls may be far more useful.