50 Ohm test probe - RF Cafe Forums

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jom
 Post subject: 50 Ohm test probe
Posted: Mon Jul 16, 2007 12:08 pm 
 
Captain
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Joined: Fri Jan 26, 2007 2:40 am
Posts: 23
Hello

Does anyone have a simple RF 50 ohms test probe idea (either build or buy) for testing a relatively low frequency radio (<500 MHz). The probe will connect into a 50 ohm spectrum analyzer but it has to not significantly load the point being tested. I need to be able to troubleshoot through a series of amplifiers to find any gain problems and whatnot.

thanks

jom
 
   
 
sm7ovk
 Post subject:
Posted: Mon Aug 27, 2007 3:52 pm 
 
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Joined: Thu Jan 11, 2007 12:59 pm
Posts: 16
Hi!

At some occasions I have made a simple probe by taking a coaxial cable and soldered a small capacitor at the end, in your case a couple of pF. In this way the load on the objekt is small - if the capacitor is small. Ground the coax by holding the shield to the PCB-ground. If the ground is a couple of cm from the measuringpoint doesn't matter at 500MHz.

Regards and good luck
Jens
 
   
 
maxwell
 Post subject:
Posted: Wed Sep 19, 2007 9:21 am 
 
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Joined: Mon Sep 01, 2003 6:59 pm
Posts: 24
Location: Boston
Check eBay for a used 50 ohm probe. I've seen them go for well under $100.

...Max
 
   
 
jom
 Post subject:
Posted: Tue Oct 16, 2007 1:17 am 
 
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Joined: Fri Jan 26, 2007 2:40 am
Posts: 23
thanks for the info!

jom




Posted  11/12/2012