ab8xx
New Member
Posts: 3 
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Post by ab8xx on Apr 15, 2009 11:33:53 GMT -5
Hello all,
This may be kind of a dumb question, but what would be the best way to configure an AIM4170 to be used as a dip meter, such as measuring the resonant frequencies of antenna traps?
I have never had to assemble any traps before and do not have a regular dip meter that would normally be used for this purpose.
Ryan AB8XX
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Post by Bob on Apr 15, 2009 18:31:47 GMT -5
Hi Ryan,
The AIM is very handy for measuring components like traps as well as coils, capacitors, and resistors.
You can connect the trap directly to the terminals of the AIM RF connector (after calibrating your adapter) and then read the resonant frequency and Q.
The calibration procedure compensates for adapters and jumper cables, so you get a reading that represents the true performance of the trap.
For fine tuning a multiband antenna with traps, you can use the "band skipping" mode to quickly scan several bands so you can see the effect of adjustments on all bands at the same time. Also, the new Marker SWR indicator is helpful for tuning multibanders.
73/Bob
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ab8xx
New Member
Posts: 3
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Post by ab8xx on Apr 17, 2009 13:23:53 GMT -5
Thank you for replying. I did not know if there was any special way to do it for traps or not. For testing the trap, I just connected my alligator test leads adapter cable and selected it's calibration file just as I would directly measure a component.
It is amazing that this little box is so capable and yet so simple to use!
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Post by hank7hp on May 12, 2009 17:43:00 GMT -5
Bob's way is the best and most accurate way - but I have used my AIM4170 with a few feet of coax and a loop of #12 AWG wire on the end - one or two turns - couple inches in diameter. I used this to initially check the trap resonances in a KT34 tribander with very light coupling to the traps.
Just use a normal cal and then sweep the cable plus loop - if you are low enough in freq it will just look like an inductor. Then if you couple it to a resonant circuit you will see a "glitch" in that sweep at the resonant frequency - I found it useful to closely match trap resonances and see the effects of linear loading tube spacings etc. This will work with any resonant circuit -
You can get more sophisticated with cals etc but this is quick and dirty. Just a chunk of cable with PL259 connectors each end a UHF barrel and solder the loop of wire into another PL259 and screw it on . I also made one with the center conductor soldered in and the other end left loose with an alligator clip and I can wrap it around a tower leg etc to look for resonances.
I make no claims for the absolute accuracy of the measured freq but it gets you close very quickly and is quite good for comparing resonant frequencies.
Off to Dayton CUL
73 Hank K7HP
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