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  #1   Report Post  
Revolvr
 
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Default Oscilloscope for Tube circuit analysis?


I am looking to get an oscilloscope to do tube preamp/amp circuit repair,
analysis and design, and for learning. Price IS an object so I am looking at
a minimum price option.

I am a bit of a newbie here, but I think I need dual trace, about 100 MHz
max, analog scope is OK. Hobbyist level scopes are OK.

Couple things I've looked at are Tektronix 2235 or 465b which seem to be
well regarded. These can be had on eBay for around $300 typically.

Any other recommendations?

I have also looked at a couple of PC based software scopes that work with
the soundcard inputs and outputs. A couple that look promising are
AudioTester at

http://www.audiotester.de/

And TrueRTA at

http://www.trueaudio.com/rta_abt1.htm

Seems to me though that I stand a high chance of blowing out my soundcard by
connecting to a signal with a DC bias or an amplifier AC signal voltage
higher than a line level input would provide. Has anyone actually used
either of these???

Thanks,

-- Rev


  #2   Report Post  
Tweetldee
 
Posts: n/a
Default

"Revolvr" wrote in message
news:YICgb.52990$vj2.19457@fed1read06...

I am looking to get an oscilloscope to do tube preamp/amp circuit repair,
analysis and design, and for learning. Price IS an object so I am looking

at
a minimum price option.

I am a bit of a newbie here, but I think I need dual trace, about 100 MHz
max, analog scope is OK. Hobbyist level scopes are OK.

Couple things I've looked at are Tektronix 2235 or 465b which seem to be
well regarded. These can be had on eBay for around $300 typically.

Any other recommendations?

I have also looked at a couple of PC based software scopes that work with
the soundcard inputs and outputs. A couple that look promising are
AudioTester at

http://www.audiotester.de/

And TrueRTA at

http://www.trueaudio.com/rta_abt1.htm

Seems to me though that I stand a high chance of blowing out my soundcard

by
connecting to a signal with a DC bias or an amplifier AC signal voltage
higher than a line level input would provide. Has anyone actually used
either of these???

Thanks,

-- Rev

You don't need 100 Mhz for most audio work; 10-20 Mhz is plenty, and those
should be fairly cheap. Since the signals that you'll be looking at will be
in the neighborhood of 20Khz max, and allowing for a 10X bandwidth reserve,
you can easily see anything that your amps/preamps will handle in a 20 Mhz
spectrum.
Along the lines of a PC-bases scope, I wouldn't run any signals directly
into the sound card. Build a compensated attenuator, and follow it with an
amplifier to get the signal up to line levels so the your sound card isn't
straining to see it. You should also provide for AC and DC coupling on the
input. That provides attenuation and isolation for your sound card. That's
the way a real scope operates.
The PC-based scopes provide several features that ordinary scopes don't; at
least in the hobbyist price range. Spectrum analysis is the most noticeable
of these and will prove to be quite useful if you're designing and building
amps.
--
Tweetldee
Tweetldee at att dot net (Just subsitute the appropriate characters in the
address)

Never take a laxative and a sleeping pill at the same time!!


  #3   Report Post  
JamesG
 
Posts: n/a
Default

I have been using a tektronix 2212 and it has worked out quite well for me.
Some capability for spectrum analysis WOULD be quite useful however if you
can acquire it (such as a PC based ocs).. Having just built my first amp in
a while, I have concluded that this capability is necessary for
comprehensive debugging of a design.
JamesG

"Revolvr" wrote in message
news:YICgb.52990$vj2.19457@fed1read06...

I am looking to get an oscilloscope to do tube preamp/amp circuit repair,
analysis and design, and for learning. Price IS an object so I am looking

at
a minimum price option.

I am a bit of a newbie here, but I think I need dual trace, about 100 MHz
max, analog scope is OK. Hobbyist level scopes are OK.

Couple things I've looked at are Tektronix 2235 or 465b which seem to be
well regarded. These can be had on eBay for around $300 typically.

Any other recommendations?

I have also looked at a couple of PC based software scopes that work with
the soundcard inputs and outputs. A couple that look promising are
AudioTester at

http://www.audiotester.de/

And TrueRTA at

http://www.trueaudio.com/rta_abt1.htm

Seems to me though that I stand a high chance of blowing out my soundcard

by
connecting to a signal with a DC bias or an amplifier AC signal voltage
higher than a line level input would provide. Has anyone actually used
either of these???

Thanks,

-- Rev




  #4   Report Post  
Paul Sanchez
 
Posts: n/a
Default

Tektronix 453 or 454 work well.
About $100(but make sure you ask if they work). I just had some dip "imply"
that it was calibrated. It turns out, he only calibrated one function.



"JamesG" wrote in message
...
I have been using a tektronix 2212 and it has worked out quite well for

me.
Some capability for spectrum analysis WOULD be quite useful however if you
can acquire it (such as a PC based ocs).. Having just built my first amp

in
a while, I have concluded that this capability is necessary for
comprehensive debugging of a design.
JamesG

"Revolvr" wrote in message
news:YICgb.52990$vj2.19457@fed1read06...

I am looking to get an oscilloscope to do tube preamp/amp circuit

repair,
analysis and design, and for learning. Price IS an object so I am

looking
at
a minimum price option.

I am a bit of a newbie here, but I think I need dual trace, about 100

MHz
max, analog scope is OK. Hobbyist level scopes are OK.

Couple things I've looked at are Tektronix 2235 or 465b which seem to be
well regarded. These can be had on eBay for around $300 typically.

Any other recommendations?

I have also looked at a couple of PC based software scopes that work

with
the soundcard inputs and outputs. A couple that look promising are
AudioTester at

http://www.audiotester.de/

And TrueRTA at

http://www.trueaudio.com/rta_abt1.htm

Seems to me though that I stand a high chance of blowing out my

soundcard
by
connecting to a signal with a DC bias or an amplifier AC signal voltage
higher than a line level input would provide. Has anyone actually used
either of these???

Thanks,

-- Rev






  #5   Report Post  
Raymond Koonce
 
Posts: n/a
Default



Revolvr wrote:

I am looking to get an oscilloscope to do tube preamp/amp circuit repair,
analysis and design, and for learning. Price IS an object so I am looking at
a minimum price option.

I am a bit of a newbie here, but I think I need dual trace, about 100 MHz
max, analog scope is OK. Hobbyist level scopes are OK.

Couple things I've looked at are Tektronix 2235 or 465b which seem to be
well regarded. These can be had on eBay for around $300 typically.

Any other recommendations?

I have also looked at a couple of PC based software scopes that work with
the soundcard inputs and outputs. A couple that look promising are
AudioTester at

http://www.audiotester.de/

And TrueRTA at

http://www.trueaudio.com/rta_abt1.htm

Seems to me though that I stand a high chance of blowing out my soundcard by
connecting to a signal with a DC bias or an amplifier AC signal voltage
higher than a line level input would provide. Has anyone actually used
either of these???

Thanks,

-- Rev



I picked up a working solid state Tenma dual trace 20MHz scope for $50
from a TV shop going out of business. I got two probes and the manual.
Works OK for me.

Raymond



  #6   Report Post  
Alan Douglas
 
Posts: n/a
Default

Hi,
For strictly audio work, you could do a lot worse than an H-P
1200A. 500kHz, 100 microvolts, differential inputs on binding posts,
extremely sharp trace. Mine has worked flawlessly for something like
20 years (cost me a dollar at a company auction).

Cheers, Alan
  #7   Report Post  
Phil Allison
 
Posts: n/a
Default


"Alan Douglas" adouglasatgis.net
....
Hi,


For strictly audio work, you could do a lot worse than an H-P
1200A. 500kHz, 100 microvolts, differential inputs on binding posts,
extremely sharp trace.



** What's this "strictly audio work .......... 500kHz .. " business ?
The minimum scope bandwidth for an "audio" technician is 20 MHz - 50 MHz
is more like it.

So called "audio" work includes:

Mosfet power amplifiers with parasitic oscillations at up to 50 MHz.
The IF signals of an FM tuner at 10.7 Mhz.
The clock frequency of a uP based audio processor.
Local oscillator signals from 10MHz up to 50 MHz inside radio microphone
Rx and Tx units.


For purely tube based circuitry a 0.5 MHz scope may be OK - but only just.




............ Phil



  #8   Report Post  
doug
 
Posts: n/a
Default

Glad you offered something constructive Phil.
Oh sorry must have been someone else.
why dont you try offering an answer instead of just cutting down everyone
else?

Doug

"Phil Allison" wrote in message
u...

"Alan Douglas" adouglasatgis.net
...
Hi,


For strictly audio work, you could do a lot worse than an H-P
1200A. 500kHz, 100 microvolts, differential inputs on binding posts,
extremely sharp trace.



** What's this "strictly audio work .......... 500kHz .. " business

?
The minimum scope bandwidth for an "audio" technician is 20 MHz - 50 MHz
is more like it.

So called "audio" work includes:

Mosfet power amplifiers with parasitic oscillations at up to 50 MHz.
The IF signals of an FM tuner at 10.7 Mhz.
The clock frequency of a uP based audio processor.
Local oscillator signals from 10MHz up to 50 MHz inside radio

microphone
Rx and Tx units.


For purely tube based circuitry a 0.5 MHz scope may be OK - but only

just.




........... Phil





  #9   Report Post  
Phil Allison
 
Posts: n/a
Default


"doug"

Glad you offered something constructive Phil.



** All my posts are highly constructive - even my responses to mindless
abuse from jerks like you Doug.

Pat Turner is the master of mindless abuse and libel - as he is
about to find out.




............ Phil



  #10   Report Post  
doug
 
Posts: n/a
Default

Sorry Phil nothing constructive in that post
And I think I read your book
How to Influence People and Make Friends
that was you wasnt it?
I understand why you come on to the newgroups now to spread your drivel..
Becauxe no-one will talk to you in real life.
have a nice one Phil
this Group will be much better whin you go away

Doug




"Phil Allison" wrote in message
u...

"doug"

Glad you offered something constructive Phil.



** All my posts are highly constructive - even my responses to

mindless
abuse from jerks like you Doug.

Pat Turner is the master of mindless abuse and libel - as he is
about to find out.




........... Phil







  #11   Report Post  
Ray Parkhurst
 
Posts: n/a
Default

Wow, guess I got ripped-off. Paid $10 for mine. Awesome 'scope! Fully
differential input and extremely wide dynamic range. This 'scope plus a 3580
spectrum analyzer and you are well set up for tube audio.

Ray Parkhurst

"Alan Douglas" adouglasatgis.net wrote in message
...
Hi,
For strictly audio work, you could do a lot worse than an H-P
1200A. 500kHz, 100 microvolts, differential inputs on binding posts,
extremely sharp trace. Mine has worked flawlessly for something like
20 years (cost me a dollar at a company auction).

Cheers, Alan



  #12   Report Post  
Phil Allison
 
Posts: n/a
Default


"doug" wrote in message
news:ryKgb.41862$9l5.27859@pd7tw2no...
Sorry Phil nothing constructive in that post




** You failed to see it.

Since you are blind.




.......... Phil






  #13   Report Post  
Revolvr
 
Posts: n/a
Default

Good ideas. Since I am only looking at tube amps and preamps, I agree 500
kHz or so will do. I'll look around on eBay for the HPs and other lower BW
Tek options.

-- Rev

"Ray Parkhurst" wrote in message
ink.net...
Wow, guess I got ripped-off. Paid $10 for mine. Awesome 'scope! Fully
differential input and extremely wide dynamic range. This 'scope plus a

3580
spectrum analyzer and you are well set up for tube audio.

Ray Parkhurst

"Alan Douglas" adouglasatgis.net wrote in message
...
Hi,
For strictly audio work, you could do a lot worse than an H-P
1200A. 500kHz, 100 microvolts, differential inputs on binding posts,
extremely sharp trace. Mine has worked flawlessly for something like
20 years (cost me a dollar at a company auction).

Cheers, Alan





  #14   Report Post  
RdM
 
Posts: n/a
Default

"Revolvr" wrote, inter alia,
in rec.audio.tubesYICgb.52990$vj2.19457@fed1read06:

: I have also looked at a couple of PC based software scopes that work with
: the soundcard inputs and outputs. A couple that look promising are
: AudioTester at
:
: http://www.audiotester.de/
:
: And TrueRTA at
:
: http://www.trueaudio.com/rta_abt1.htm

You might also like to look at http://www.dazyweblabs.com/
I've downloaded all these, but haven't actually tried them yet.
Sure are "purty" looking interfaces though,
and the site seems tube-friendly, too ...
[My 0.02c ... maybe others have tried their suite out?]
RdM
(back, after isp difficulties and changeovers ... ;=})
  #15   Report Post  
RdM
 
Posts: n/a
Default

RdM wrote:

: RdM
: (back, after isp difficulties and changeovers ... ;=})

OOps ... that'd be rdm@ with a reversed country code, actually!
Inter alia ... several addresses now, don't want to get cut off again!
Not that I've been getting much email ... and I do know I owe some ...
Catching up ASAP ... apologies to those concerned! Cheers! RdM!


  #16   Report Post  
Mikkel C. Simonsen
 
Posts: n/a
Default

Revolvr wrote:

I am looking to get an oscilloscope to do tube preamp/amp circuit repair,
analysis and design, and for learning. Price IS an object so I am looking at
a minimum price option.

I am a bit of a newbie here, but I think I need dual trace, about 100 MHz
max, analog scope is OK. Hobbyist level scopes are OK.


I would look for one of the cheap 20MHz dual trace scopes. I don't think
it matters much if you get a Kikusui (or however they spell it), Leader,
Hameg, Philips or whatever else you can find.

I bought an old Leader scope on eBay, and that works fine for me. I
don't remember how much I paid for it, but it wasn't much.

Best regards,

Mikkel C. Simonsen
  #17   Report Post  
Alan Douglas
 
Posts: n/a
Default

Hi,

Good ideas. Since I am only looking at tube amps and preamps, I agree 500
kHz or so will do. I'll look around on eBay for the HPs and other lower BW
Tek options.

-- Rev


There's no law that says you can't have two scopes: start with what
you can easily find, and then you'll be in a better position to know
what you need.

Cheers, Alan
  #18   Report Post  
Phil Allison
 
Posts: n/a
Default


"Mikkel C. Simonsen" ...


I would look for one of the cheap 20MHz dual trace scopes. I don't think
it matters much if you get a Kikusui (or however they spell it), Leader,
Hameg, Philips or whatever else you can find.



** The Hameg and the Philips ones will have one **major advantage** -
a magnetic ( mu-metal) shield on the CRT.

Practically essential for working with any kind of AC powered
amplifiers - no cheap Asian scopes have them fitted and the trace
shimmers like crazy in the presence of an AC field. My pet hate.





............ Phil


  #19   Report Post  
Jimmy
 
Posts: n/a
Default

I would get the 2235 if the money is not too much of a problem. Some will
say 100Mhz is over kill but you will probably find other uses for it where
you may need it. Lesser scopes arent that much cheaper and they are usually
lesser in more ways than bandwidth.


"Revolvr" wrote in message
news:YICgb.52990$vj2.19457@fed1read06...

I am looking to get an oscilloscope to do tube preamp/amp circuit repair,
analysis and design, and for learning. Price IS an object so I am looking

at
a minimum price option.

I am a bit of a newbie here, but I think I need dual trace, about 100 MHz
max, analog scope is OK. Hobbyist level scopes are OK.

Couple things I've looked at are Tektronix 2235 or 465b which seem to be
well regarded. These can be had on eBay for around $300 typically.

Any other recommendations?

I have also looked at a couple of PC based software scopes that work with
the soundcard inputs and outputs. A couple that look promising are
AudioTester at

http://www.audiotester.de/

And TrueRTA at

http://www.trueaudio.com/rta_abt1.htm

Seems to me though that I stand a high chance of blowing out my soundcard

by
connecting to a signal with a DC bias or an amplifier AC signal voltage
higher than a line level input would provide. Has anyone actually used
either of these???

Thanks,

-- Rev




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