Signal Generator & Osilloscope Probes

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Signal Generator & Osilloscope Probes

Post by Where did I put that... on Tue Jun 17, 2008 12:11 pm

I just got a Precision signal generator and an RCA oscilloscope that I know work because I saw them in operation before I bought them. The stipulation was that the seller needed to keep the test leads.

I have a coax cable with the single contact screw-on microphone connector and the other end of the 6-foot lead is cut. I need to know if there is a way I can add something to the cut end to get it to work. I'm new at anything bigger than a VTVM but I've heard about 50-ohm termination ends and capacitor isolators and such but what goes where is a total mystery.

Can anyone shed some light on my sorry situation?

Robin
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Re: Signal Generator & Osilloscope Probes

Post by Resistance is Futile on Wed Jun 18, 2008 3:45 am

You will need to get a commercial built probe, unless your very skilled at making them. What type of connectors do you have on the scope?

Are they BNC? or PHONO? RCA type?

The size of cap and resistor are important too. because they need to be adjustable on more expensive sets. As the leading and trailing edge of the square wave pattern need to symmetrical (for frequency compensation.) Also for attenuation of 1X, 10X or such.

The ground or shield must be of a coax type that is rated as 50ohms to be a standard or your readings will be ambiguous and meaningless. You also will need a standard to reference the probe to. Such as a 1 KHz square wave at 50 millivolts or such I forget myself.

Some Scope's have a calibrator tie point that you can hook your probe up to.
Sounds like its complicated things right?

Hope this helps some.

Click on this link for construction Ideas
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Re: Signal Generator & Osilloscope Probes

Post by Where did I put that... on Wed Jun 18, 2008 4:01 pm

I'll try to add a picture of the type of connector my scope has. It needs to be like #3 (75-MC1F).



Is there a company that makes adapters from this type to the BNC?

Robin


Last edited by Where did I put that... on Fri Jun 27, 2008 4:39 pm; edited 3 times in total (Reason for editing : I got this picture thing down, now!)
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Re: Signal Generator & Osilloscope Probes

Post by Resistance is Futile on Sun Jan 18, 2009 6:25 pm

Hers a picture rather than a drawing Iv'e only seen that connector with a 1/4'' male phono jack on the other end.

http://www.alliedelec.com/Search/productdetail.aspx?SKU=932-1045
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Re: Signal Generator & Osilloscope Probes

Post by tinwhisker on Tue Feb 10, 2009 9:25 pm

You might think about changing those old style connectors to "BNC" standard connectors, on your test equipment. This will simplify finding ready made probes, patch cables (RG-58 with BNC's on both ends) with various lengths.

For low impedance testing, like audio amp output testing, RG-58 test cables with banana plugs, alligator clips, grabber clips etc., are ok, with BNC on the other end is fine.

If the signal generator is of the R.F. type, the patch cable (coax) impedance, should match the generator's output impedance and a termination load of the same impedance is handy to have and it's proper place is at the far end of the cable. (not at the generator end).

Charlie

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Re: Signal Generator & Osilloscope Probes

Post by TexMac on Fri Feb 20, 2009 5:45 am

The scope can get fairly complicated and is above my pay grade, but for the signal generator, if all you plan to do is align old tube radios, a pair of alligator clips at the end of the coax is all you need and all my Precision E200-C came with. One connected to the center wire and one connected to the shield. Your radio schematic will usually specify any special dummy antenna you will need to clip in series with it. I use a .05mfd cap in series with the shield (ground) lead in case there is any stray AC around on all my signal generators even though some have one built in.

Those connectors like you show are available from RadioDaze, but they have been having some shipping delays lately. It is possible Mouser has them and you can track them down by part number since you have the manufacturers part number.

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Re: Signal Generator & Osilloscope Probes

Post by Don Cavey on Fri Feb 20, 2009 6:31 pm

At the risk of being stoned by some of you guys, there are probes on 'That Auction Site' that we all love to hate. Some are modern construction and often are inexpensive. If you are just doing hobby work, I suggest that you don't need the absolute best. I also agree that changing the connector to BNC is a good move unless you want to keep originality and/or the scope/generator is "Collectible".

Just a thought...

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Re: Signal Generator & Osilloscope Probes

Post by mikeinkcmo on Sat Feb 21, 2009 9:31 am

Personally, I'd suggest all your test equipment, that handles less than 25 watts or so, be converted to either GR (General Radio / aka twin bananna) or BNC connectors. This excludes AC power sources of course. It makes interconnect during testing alot easier, and reduces the number of "special" cables to zero.

For those connections you can't change if you're working on car radios, audio, or other special equipment, just make some very compact "adaptors".

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