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-   -   Function Generators (http://www.diyaudio.com/forums/equipment-tools/167992-function-generators.html)

airboss 4th June 2010 05:59 PM

Function Generators
 
Here's an example of a Tek function generator. Tektronix CFG250 Function Generator (Reduced!) - eBay (item 370317262851 end time Jun-06-10 11:09:28 PDT)
Not too spendy but still, I'm told that the Tiawan stuff is not repairable at any price. Compare this to, say, the $160 function generator at AES. Obviously this has a wider bandwidth and a few other bells and whistles. I think it's output is at about 50 ohms so it may not be the best choice for Tube/Valve work without a DIY interface which might introduce sleeze into measurements if not perfectly designed.

There may be others to consider. Fluke, Wavetek, HP, etc.

I will not be doing ANY digital trouble shooting. Analog only.

Thoughts?

firechief 4th June 2010 08:18 PM

Yea, I personally would rather have the higher impeadance source for the kind of audio work that this forum is about. The AES item is going to be quite usable
Features:
Frequency range - 10 Hz ~ 1 MHz, 5 decade bands
Accuracy = 10Hz ~ 1 MHz - +/- 5% + 2Hz
Output control- 0dB/-20dB/-40dB and fine adjuster
100 Hz ~ 100 KHz +/- 3% + 3 Hz
Output Voltage Floating: within +/- 1.5dB
Sine Wave Output:
Range: 10Hz~1MHz
Output Voltage: 8V RMS max
Output Distortion: <.05% - 500Hz~50KHz
In either case accurate measurments are going to depend on a secondary measurment tool, like a quality scope. A person will not be able to just read the dial on either of these and get a real life number, just close.

1audio 5th June 2010 04:02 AM

Why a higher impedance for your source? So you can see the effects of the shunt capacitance? Its easy to add a resistor in series to see the effects of a high source impedance (never good).

I would shop for a Krohn Hite function generator. They have very high performance and are quite fixable. Very high analog art. The prices I see on eBay are crazy for 20 year old boxes. (I may offload some of my collection if those are prices people pay.)

airboss 5th June 2010 04:29 AM

Quote:

Originally Posted by 1audio (Post 2207713)
Why a higher impedance for your source? So you can see the effects of the shunt capacitance? Its easy to add a resistor in series to see the effects of a high source impedance (never good).

I would shop for a Krohn Hite function generator. They have very high performance and are quite fixable. Very high analog art. The prices I see on eBay are crazy for 20 year old boxes. (I may offload some of my collection if those are prices people pay.)

Hey One: I already got set straight by one of the brain trust fellers that I conferred with. Low impedance is good for both tube and SS.

Krohn Hite eh? Never heard of them. German I suppose? We'll see, I generally study the market awhile before taking the plunge. I've never gone wrong with Tek, HP, or Fluke. I'll add Krohn Hite to the list. I bought a Tek 2465 the other day with a scratchy trace intensity pot. I'm pretty sure I have one, if not I know a service center that has them. $152.49. It was a mistake really, I don't need another scope, my 453 has been a trustworthy tool for 25 years that I've had it. But I just couldn't let the guy have it for $149 you know? So I wacked it in the last 15 seconds manually with a $152.58 and be danged if I didn't get it. I will be able to use the 2 extra inputs though. In guitar amps it's nice to know which stage clips when. If I sell the 453, needing no work, and clean as a whistle, with tek 10K probes, I'll recover my investment less shipping.

Thanks for the reply.

airboss 5th June 2010 05:16 AM

Quote:

Originally Posted by 1audio (Post 2207713)
Why a higher impedance for your source? So you can see the effects of the shunt capacitance? Its easy to add a resistor in series to see the effects of a high source impedance (never good).

I would shop for a Krohn Hite function generator. They have very high performance and are quite fixable. Very high analog art. The prices I see on eBay are crazy for 20 year old boxes. (I may offload some of my collection if those are prices people pay.)

Hey Demian, I'm about to send a PM.

1audio 5th June 2010 05:20 AM

Krohn Hite Krohn-Hite Corporation - A Leading Manufacturer of Test and Measurement Instruments Since 1949 US company started in 1949. Known for filters and function generators. Also for the ultra low distortion oscillator 4400a.

Mooly 5th June 2010 06:32 AM

I use both an ancient Belco,
http://www.diyaudio.com/forums/parts...-info-etc.html

and a Tenma function generator,
Tenma 72-5016 | Used Function Generator | Used Test Equipment | Refurbished Test Equipment

which tbh is what I use 99% of the time.

airboss 9th June 2010 12:23 AM

I just nabbed this one for less than half the asking price. It pays to make offers eh?

310216924231
Krohn-Hite Generator Model 5400B Tested - eBay (item 310216924231 end time Jun-08-10 14:57:03 PDT)

http://i.ebayimg.com/15/!BsD+2)QEWk~...!qZT4Q~~_3.JPG

1audio 9th June 2010 12:31 AM

Good deal, it should work well for your needs.

airboss 9th June 2010 04:01 AM

Quote:

Originally Posted by 1audio (Post 2211238)
Good deal, it should work well for your needs.

The only thing I'm worried about is the push/release button selectors. I've had equipment with those type switches that become unreliable. If it's a sealed switch it's probably ok depending on use. In a production environment it may have never strayed from a single setting. If it's not sealed break out the DeOxit.

I missed the 5200B yesterday for $36 because of glitch in my home network. Who knows how high the other guy bid? Can't worry about the fish that got away.

Thanks for the heads up on this equipment!

Oh, what's the extra square wave output jack for?


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