A single order lowpass filter
fc = 1MHz maybe?
If you want to get fancy you could add buffers as well.
In fact, you might need to as the filter could alter your nice TTL
waves. You could then use an active filter. It might be handy to build
and have around anyway.
--
Martin K

Gus S Calabrese wrote:

>I have a handheld frequency counter that measures from DC to 2 GHz.
>It has a BNC connector and 50 ohms input impedance.
>( Battery operated )
>It does okay measuring transmitter frequencies with a stub antenna.
>I tried to measure a TTL level signal at that is around 500KHz.
>The readout bounced around and was clearly reading RFI from the board.
>What kind of probe can I put on this puppy to read TTL signals and  
>ignore
>RFI ?
>Regards
>
>Gus S Calabrese
>Denver, CO
>720 222 1309     303 908 7716 cell
>I allow everything with  "spamcode2006"  in the subject or text to  
>pass my spam filters
>
>
>  
>


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