Low-distortion Audio-range Oscillator - Page 86 - diyAudio
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Old 15th November 2012, 06:37 PM   #851
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Quote:
Originally Posted by Samuel Groner View Post
Related to this topic (no worth starting another thread): I've had the chance to scan the manual of the calibration fixture (067-0938-00) which was used to verify distortion performance of the Tektronix SG505. The PDF is made available here:

067-0938-00 - TekWiki

Good inspiration for those interested in building a passive notch filter!

Samuel
You would think they could compress this file a little more. Seems pretty much
what Bruce Hofer told me, the passive notch is the only way to go.

EDIT - none around today but one sold for ~$300 a few years ago.
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Last edited by scott wurcer; 15th November 2012 at 06:50 PM.
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Old 17th November 2012, 06:28 AM   #852
RNMarsh is offline RNMarsh  United States
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Pretty nice... but it atten the 2nd by almost 10DB. Put that number back in after the measurement is a pain but do-able if you have to. I have similar problem with my variable notch filter - B&K #1607... too broad still. Guess I could use it in an opamp feedback loop.
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Old 17th November 2012, 11:47 PM   #853
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Originally Posted by RNMarsh View Post
Pretty nice... but it atten the 2nd by almost 10DB. Put that number back in after the measurement is a pain but do-able if you have to. I have similar problem with my variable notch filter - B&K #1607... too broad still. Guess I could use it in an opamp feedback loop.
That puts distortion back in, if it's not a pain for Tek and AP it's OK by me.
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Old 18th November 2012, 11:07 AM   #854
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by scott wurcer View Post
EDIT - none around today but one sold for ~$300 a few years ago.
Reminds me -- maybe not this manual but many --
Many test equipment manuals can be downloaded at: www.BAMA.edebris.com/manuals

They are all free.
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Old 18th November 2012, 07:08 PM   #855
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Even though that article claimed -120dB THD from almost the simplest possible oscillator no one has tried it? Time of year to find plenty of C7 bulbs.
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Old 18th November 2012, 07:11 PM   #856
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Time of year to find plenty of C7 bulbs.
...and here i thought Santa Claus had been banished by the Regime.
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Old 18th November 2012, 09:25 PM   #857
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...and here i thought Santa Claus had been banished by the Regime.

Yup, ACE had 'em all (the flickering ones are probably to be avoided).
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Old 20th November 2012, 08:01 PM   #858
RNMarsh is offline RNMarsh  United States
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I'm in the process of trouble-shooting an HP339A (spare parts buy) and found a dozen coax lines plugged into various gold plated pcb and they used funky made RCA jacks and plugs which are tin or something - not gold plated... even on the output of the very sensitive oscillator. Geeze. And thru crummy corroded switch contacts and fuses/fuse holder and Molex-like contections (also tin) the pristine signal has to go thru. Geeez. After I find the problem (so far one relay contact not making contact) I'll have to replace or clean such contact points. Great electronics design circuitry but all the mechanicals are inferiour.

Last edited by RNMarsh; 20th November 2012 at 08:04 PM.
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Old 20th November 2012, 08:08 PM   #859
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Richard-
Why would you think HP would be "audiophile" about such things? They reserved the gold to gold stuff for the RF instrumentation.

My Boonton uses SMC connectors for the audio links except for the balanced input, which is a gold Molex. but Boonton is an RF instrument company, not an audio company.
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Old 20th November 2012, 09:30 PM   #860
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Default never entered their mind -

Quote:
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Richard-
Why would you think HP would be "audiophile" about such things? They reserved the gold to gold stuff for the RF instrumentation.
What makes you think/assume, that is what I think? I'm not even an audiophile myself.... any more than you are. I'm sure that audiophile never entered their minds. But reliability should have... always did before. So, why did they Gold Plate the PCB traces on the oscillator board. RF? (dont need an answere). It was just a mess up..... even the front panel knobs are mostly cracked/broken on most units as they used polystyrene for dials etc etc etc. You can make excuses for them.. but, I ain't giving them a break on this model....
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