"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!!