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50 Ohm test probe - RF Cafe Forums
Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


jom
 Post subject: 50 Ohm test probe
Posted: Mon Jul 16, 2007 12:08 pm 
 
Captain
User avatar

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 
 
Captain
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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 
 
Captain
User avatar

Joined: Fri Jan 26, 2007 2:40 am
Posts: 23
thanks for the info!

jom






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