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CFC250 Frequency Counter

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tronixstuff
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Joined: June 16th, 2010, 2:08 am

CFC250 Frequency Counter

Post by tronixstuff » June 16th, 2010, 2:42 am

Hello
I have just bought a CFC250 100 MHz frequency counter, however it did not come with a probe (nor a manual). Below the BNC socket on the front is printed "1M ohm, 40pF". I can find probes with 1M impedance, however they only have 35 pF rating. Would they be ok?

Thank you very much
John

Carl M
Tektronix Applications
Tektronix Applications
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Joined: July 30th, 2008, 4:45 pm
Country: United States

Re: CFC250 Frequency Counter

Post by Carl M » June 18th, 2010, 1:50 pm

That is a very old instrument (1988). The only two probes that can compensate that much capacitance are the P6101B and the P6015A.

But lets think about this for a second... it's a frequency counter so its just going to look at the edges. You may be able to use a P2220 or just some BNC to alligator clips if the ringing and reduced sensitivity don't cause false edges.
Tektronix Application Engineer

tronixstuff
Posts: 5
Joined: June 16th, 2010, 2:08 am

Re: CFC250 Frequency Counter

Post by tronixstuff » June 20th, 2010, 5:13 am

Hello Buck
Thank you very much for your answer.
Cheers
john

tronixstuff
Posts: 5
Joined: June 16th, 2010, 2:08 am

Re: CFC250 Frequency Counter

Post by tronixstuff » June 30th, 2010, 5:34 am

Just to follow up, it does work nicely with the alligator clips to a BNC plug.
Interestingly, the counter still works very well - the update speed is a little slower than a new counter, but it is accurate. A testament to Tektronix.

Carl M
Tektronix Applications
Tektronix Applications
Posts: 796
Joined: July 30th, 2008, 4:45 pm
Country: United States

Re: CFC250 Frequency Counter

Post by Carl M » July 7th, 2010, 2:13 pm

glad to hear your success is a result of my suggestion :mrgreen:
Tektronix Application Engineer

tronixstuff
Posts: 5
Joined: June 16th, 2010, 2:08 am

Re: CFC250 Frequency Counter

Post by tronixstuff » August 11th, 2010, 12:14 am

Now I am even more impressed. Using a function generator, I measured various sine wave frequencies with the Tek CFC250 and a new Fluke 233. After 25-odd years the Tektronix still reads like new.
Here are a few photos I took: http://www.flickr.com/photos/tronixstuf ... 700675762/
Quality is remembered long after price is forgotten. I now know which brand of DSO to buy!
cheers
john

tronixstuff
Posts: 5
Joined: June 16th, 2010, 2:08 am

Re: CFC250 Frequency Counter

Post by tronixstuff » September 2nd, 2011, 11:45 pm

Well another year has passed, and my CFC250 is still plugging along nicely. :)

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