Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => AmpTools/Tech Tips => Topic started by: sawdust on July 31, 2008, 06:01:00 am

Title: Looking to buy a used O'scope; preferred bandwidth for Guitar amps?
Post by: sawdust on July 31, 2008, 06:01:00 am

I was looking on Ebay and found many Tektronix scopes in the 20/30 mhz to 100 mhz range. Is a 100 mhz too fast for general amp troubleshooting? Should I stick to something up to 50 mhz and no higher?

Title: Re: Looking to buy a used O'scope; preferred bandwidth for Guitar amps?
Post by: gainer on July 31, 2008, 03:12:32 pm

 I've never seen a scope that you couldn't slow the time/div down till the beam slowly traversed the screen.


 IF the scope will never be used for anything but guitar amps, any modern scope's bandwidth will be sufficient IMO.

Title: Re: Looking to buy a used O'scope; preferred bandwidth for Guitar amps?
Post by: DummyLoad on July 31, 2008, 05:58:07 pm

http://cgi.ebay.com/BK-Precision-1530-30MHz-Oscilloscope-w-Probe_W0QQitemZ160266490121QQcmdZViewItem?hash=item160266490121&_trkparms=72%3A552%7C39%3A1%7C66%3A2%7C65%3A12&_trksid=p3286.c0.m14.l1318


http://cgi.ebay.com/HITACHI-V-650F-V650F-OSCILLOSCOPE-60-MHz_W0QQitemZ330257311342QQcmdZViewItem?hash=item330257311342&_trkparms=72%3A552%7C39%3A1%7C66%3A2%7C65%3A12&_trksid=p3286.c0.m14.l1318

Title: Re: Looking to buy a used O'scope; preferred bandwidth for Guitar amps?
Post by: tubesornothing on July 31, 2008, 08:02:39 pm

A dual channel scope is good, cause you can put it on input and output, and see the diff.  You need about 40kHz bandwidth, so just about anything will work. Make sure the frigging thing is focused nicely before purchasing.  I also like on screen voltage and freq measurement.  I also have a USB scope so I can take and save shots, but the one I use is tres expensive, but is fantastico for audio.

Title: Re: Looking to buy a used O'scope; preferred bandwidth for Guitar amps?
Post by: PRR on July 31, 2008, 09:28:35 pm

> Is a 100 mhz too fast

I did a LOT of work with a 'scope claimed 450KHz (0.45MHz!).

On tubes, I have never needed the speed of my 15MHz 'scope. If I didn't already have five 'scopes, I'd get that 5MHz HeathKit back from my nephews.. very sweet machine.

This new/cheap scope looks cute:
http://www.surplusgizmos.com/New-10MHz-Mini-Analog-Oscilloscope-Model-CA8016_p_131-1031.html

Single-trace. 95% of the time you will be working single-trace anyway. Dual-trace can be very handy, but is an Advanced Technique, and not worth spending more for. Or wrestling the dirty switches on a used 'scope.

Title: Re: Looking to buy a used O'scope; preferred bandwidth for Guitar amps?
Post by: PRNDL on August 01, 2008, 08:05:19 am

I have a Tektronix 922 at 15MHz and really like it, although a 100 MHz scope would be sweet.

The difficulty with used scopes on the bay is that most need repairs, especially those with lower prices and "as is".
There are, however, a few sellers that offer rebuilt and calibrated units usually at higher prices.
It is possible to repair them, if you can find schematics. Many prefer old Tektronix units for this.
I had to fix mine.

The new scope for $160 looks great, as does the $50 Hitachi described as "perfect".

You'll also need a probe or two, and a signal generator.

Title: Re: Looking to buy a used O'scope; preferred bandwidth for Guitar amps?
Post by: Rosser on August 01, 2008, 11:38:35 am

I can't vouch for it one way or the other, but I noticed this new 20 Mhz scope from Weber for $275. Comes with 2 probes.

https://amptechtools.powweb.com/scope.htm

Title: Re: Looking to buy a used O'scope; preferred bandwidth for Guitar amps?
Post by: FUNK on August 18, 2008, 07:06:31 pm

if you need a signal generator let me know and I'll give you a freeware program (frequency generator) so you can use your computer as a signal generator...