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Old 16th April 2013, 06:00 AM   #1831
Salas is offline Salas  Greece
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Default Know your wiggles

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Old 16th April 2013, 07:17 AM   #1832
stajo is offline stajo  Sweden
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Cool. Lower left corner is a common one on my scoopings, but according to the pic the upper right one, rounded in all corners is better? Phase shift, what does that mean, what happens in the amp and why?

Btw I was at a friend last night and exchanged a bag of beer for one of his 5 scopes (or two actually) so now I possibly have something to relate the other measures to. Came home a bit late and a bit unsteady on hand so I skipped the HV fiddle.
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Old 16th April 2013, 09:57 AM   #1833
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Thanks for the info
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Old 16th April 2013, 11:03 AM   #1834
stajo is offline stajo  Sweden
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Well. I dont know if theres crap behind the buttons or behind the probes but this is what I could get out of the old Hameg 303-6 I borrowed.
First pic rectifiers (first C) 0,2 V/div 2 ms/div, second pic on second C 5 mV/div 5 ms/div third pic over dummy without SSHV 5mV/div 5 ms/div, fourth pic on SSHV dummy 5 mV/div 1 ms/div
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File Type: jpg 6V6 021 (3000x2000).jpg (700.2 KB, 93 views)
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Last edited by stajo; 16th April 2013 at 11:11 AM.
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Old 16th April 2013, 11:18 AM   #1835
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Old 16th April 2013, 11:42 AM   #1836
stajo is offline stajo  Sweden
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The Pico must read some noice from the diffprobe. I wonder if a thing like this could make it usable?
100MHz Oscilloscope High Voltage Clip Passive Probe, X100, Max. 2000VDC: Amazon.com: Industrial & Scientific
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Old 16th April 2013, 02:36 PM   #1837
massimo is offline massimo  Italy
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.... Need to get a good sig gen....
Buzz, look for a Leader LAG120B (pls note B), they are cheap and worth every penny. Discard LAG120A, not as good.
An example: Leader Lag 120 Audio Frequency Generator Test Stereo Amplifier | eBay
If you're lucky, you may also find a LAG126 or if you have some spare money, buy an Audio Tester 192A, same sig gen and a nice dual ch analogue RMS voltmeter with double needle for almost free
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Old 16th April 2013, 02:54 PM   #1838
iko is offline iko  Canada
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For those of you interested in testing your amplifiers, I built a version of this oscillator

Injection-lock a Wien-bridge oscillator | EDN

and got it to measure distortion of about 0.0006% (-104dB) at about 5V RMS output. Why this is significant? Because you will pay big $$ for a signal generator that has such output at such low distortion, but it'll cost very little to build the circuit in the above link. The problem with a sound card like the E-MU 0404 used to generate the signal is that as soon as you want a signal higher than about 300mV RMS you'll notice that the distortion of the generated signal is quite high.

In my opinion this little oscillator is good enough for testing tube gear. If people are interested I can post construction and parts choice details (which opamp, which light bulb, which buffer for output, etc.).
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Old 16th April 2013, 03:02 PM   #1839
stajo is offline stajo  Sweden
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If people are interested
Absolutely Iko!
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Old 16th April 2013, 03:10 PM   #1840
Salas is offline Salas  Greece
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Well. I dont know if theres crap behind the buttons or behind the probes but this is what I could get out of the old Hameg 303-6 I borrowed.
First pic rectifiers (first C) 0,2 V/div 2 ms/div, second pic on second C 5 mV/div 5 ms/div third pic over dummy without SSHV 5mV/div 5 ms/div, fourth pic on SSHV dummy 5 mV/div 1 ms/div
All in order. Told ya it was a ghost.
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