AIM Antenna Analyzer

AM Radio discussion. Directional arrays are FUN!
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Deep Thought
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Re: AIM Antenna Analyzer

Post by Deep Thought » Mon Oct 10, 2011 12:47 pm

I just did that for an 'unofficial' check on a non-151(c) array following some damage repair. Unfortunately I did not have anything to compare it to but it did read the loops at about what I expected given the line lengths.

By the way, the issue with mine that I forgot to report here (sorry about that) turned out to be a combination of the RF connector starting to get flakey and this unit's rather high sensitivity to reactance in calibration loads. Be 100% sure that whatever you use to calibrate it has as close to zero reactance over the frequencies of interest as possible. As little as +j5 in the AM band will cause the symptoms I observed. I suggested adding a test to the calibration routines to detect this condition but it fell on deaf ears so beware of your calibration devices if you see odd behavior like I did.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

WALKINGMAN
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Re: AIM Antenna Analyzer

Post by WALKINGMAN » Wed Jul 22, 2015 10:21 pm

Hi all,

I am ordering an AIM 4300DX its preferred over AIM 120 due to limited budget. My question is if I measured the impedance of folded unipole antenna tower via trap(to prevent overloading from nearby station) do the measured impedance is accurate ? also is the static drain coil inside the ATU could it helps in rejecting nearby stations induced signals. our antenna tower dont have yet thanks


Tony

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Deep Thought
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Re: AIM Antenna Analyzer

Post by Deep Thought » Thu Jul 23, 2015 8:37 am

The PowerAIM is the only unit that will reliably measure an AM tower. The others will be swamped out by any incoming RF.

The addition of a series capacitor to the skirt feed line when measuring allows you to get the +jX down to something that an OIB can measure. You also measure the capacitor at the frequency of interest and add its jX to the skirt reading.

The static drain won't give you any isolation due to its very high reactance. That's kind of the point... :wink:
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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kkiddkkidd
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Re: AIM Antenna Analyzer

Post by kkiddkkidd » Thu Jul 23, 2015 1:04 pm

I have done preliminary measurements of lines for several arrays with mine and the consultants didn't complain. I'm not sure about the loops themselves but I would assume that it would as long as you know what freq they were originally swept at.
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Kevin C. Kidd CSRE/AMD
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AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
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Deep Thought
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Re: AIM Antenna Analyzer

Post by Deep Thought » Thu Jul 23, 2015 1:47 pm

Walkingman's talking about measuring a unipole skirt...he reanimated an old topic with his post.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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kkiddkkidd
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Re: AIM Antenna Analyzer

Post by kkiddkkidd » Thu Jul 23, 2015 2:19 pm

Ah... Sorry.
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rich wood
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Re: AIM Antenna Analyzer

Post by rich wood » Thu Jul 23, 2015 7:02 pm

I have been using an AIM 120 and an OIB 3 on tune up/ troubleshooting calls. If the impedance's are reasonable both units agree in readings. If the reactance is above -400 the AIM gets different readings when you hit rescan? Sounds like some of the instability you experienced Deep Thought. This symptom was seen on a monopole skirt and the OIB when put in line increased the reactance and the transmitter would only run at reduced power.

WALKINGMAN
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Re: AIM Antenna Analyzer

Post by WALKINGMAN » Thu Jul 23, 2015 7:11 pm

That is why asking this since I have VA1 i used only it in cold measurement , due to high RF voltage presence of the tower steel that could burnout the unit. the most important thing is to measure the antenna impedance and it cannot be avoided of RF induced from nearby station that will damage the measuring equipment and It might be that happen again using 4300DX. Im still doing ordering from chris scott the tunable am filter could it be help protecting the AIM4300 while i make my measurement as already identified the station that induces the RF.


tony

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Re: AIM Antenna Analyzer

Post by WALKINGMAN » Thu Jul 23, 2015 7:30 pm

The PowerAIM is the only unit that will reliably measure an AM tower. The others will be swamped out by any incoming RF.

But what about in location that have no rf induced signal to the tower is the 4300dx wont still give the accurate reading compare to AIM120? or even after calibrating at the end of the trap. is the reading might be corrupted?

tony

pioneer
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Re: AIM Antenna Analyzer

Post by pioneer » Fri Jul 24, 2015 12:24 pm

WALKINGMAN wrote:Hi all,

I am ordering an AIM 4300DX its preferred over AIM 120 due to limited budget. My question is if I measured the impedance of folded unipole antenna tower via trap(to prevent overloading from nearby station) do the measured impedance is accurate ? also is the static drain coil inside the ATU could it helps in rejecting nearby stations induced signals. our antenna tower dont have yet thanks


Tony
Use an series LC circuit from tower to GND or in the ATU tuned to the frequency of the nearby station.

Martin

WALKINGMAN
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Re: AIM Antenna Analyzer

Post by WALKINGMAN » Fri Jul 24, 2015 4:52 pm

thanks

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