Using the AIM to measure matched line loss

A correspondent wrote seeking explanation of difficulty he was having measuring line loss using the advice given in the AIM manual using a scan with either O/C or S/C termination:

Note the one-way cable loss is numerically equal to one-half of the return loss. The return loss is the loss that the signal experiences in two passes, down and back along the open cable.

Because my correspondent was using one of the versions of AIM that I know to be unreliable, I have repeated the measurements on a cable at hand using AIM_900B to demonstrate the situation.

The test cable I have used is 10m of RG58C/U which I expect should have matched line loss (MLL) of 0.26dB, but I expect this to be a little worse as it is a budget grade cable that I have measured worse in the past. Continue reading Using the AIM to measure matched line loss

A walk through of a practical application of AIMuhf/AIM900A #2

I mentioned at A walk through of a practical application of AIMuhf/AIM900 that I wasn’t all together happy with feed point R at resonance, at 40Ω it was perhaps a touch high for a 2m quarter wave ground plane on a largish vehicle roof.

AIMuhfRepeated measurement of the DC resistance from the coax plug sheild to car body yielded unstable resistance ranging from 1 to 10Ω. If stable low DC resistance is not achieved, this feed line won’t work properly for RF. Continue reading A walk through of a practical application of AIMuhf/AIM900A #2

A walk through of a practical application of AIMuhf/AIM900

This article describes the use of the Array Solutions AIMuhf/AIM900 to test a mobile antenna installation, a quarter wave whip for 2m with about 4m of RG58 cable which has been previously installed and tuned.AIMuhf

 

The exercise is motivated by a perception that the antenna is not working as well as it should.

Screenshot - 16_05_2015 , 14_38_07

Above is a scan of the VSWR. It indicates problems, there should be a main VSWR dip around the high end of the 2m band (147MHz), but instead the minimum is nearer 160MHz. Clearly there is an antenna connected to the far end of the line in some form (ie the inner conductor is not simply broken), but there could be a high resistance in the inner conductor or shield connection (the latter is common issue with this type of antenna base). Continue reading A walk through of a practical application of AIMuhf/AIM900

Accuracy of AIMuhf system – AIM865A vs AIM885Gx on a ferrite cored inductor

AIMuhfAt Accuracy of AIMuhf system – AIM865A vs AIM882 vs AIM885 on a ferrite cored inductor I compared measurement of a small ferrite cored inductor on three ‘production’ releases of the AIM program.

Since then, AIM885A was released and it had problems as mentioned at AIM 885A produces internally inconsistent results.

Since then, AIM882, AIM885, and AIM885A have been pulled.

The developer advised on his support forum I’m sorry but version 885A has some problems. I’m working an update. In the meantime use the mature version AIM_865A.

Today, he posted a link to AIM885Gx (a declared beta release which presumably fixes problems in the pulled versions AIM882, AIM885, and AIM885A). Continue reading Accuracy of AIMuhf system – AIM865A vs AIM885Gx on a ferrite cored inductor

AIM 885A produces internally inconsistent results

 

AIMuhfFurther to AIM 885 produces internally inconsistent results

A new release, AIM885A appeared recently.

In the common theme of one step forward, two steps backwards, this version produces error popups when started.

Screenshot - 15_04_2015 , 17_41_08

The above popup appears twice when starting AIM885A. Just another symptom to undermine confidence in the system. It doesn’t make sense to me, and the program appears to otherwise start and run. Continue reading AIM 885A produces internally inconsistent results

Accuracy of AIMuhf system – AIM865A vs AIM882 vs AIM885 on a ferrite cored inductor

AIMuhfThis article builds on Accuracy of AIMuhf system – AIM865A vs AIM882 on a ferrite cored inductor by adding a measurement using AIM885 of the same test inductor.

 

Inductor1

Above is the test inductor. It comprises 6 turns of 0.5mm PVC insulated wire wound on a BN-43-202 binocular balun core. Continue reading Accuracy of AIMuhf system – AIM865A vs AIM882 vs AIM885 on a ferrite cored inductor

AIM885 Refer To Antenna checkout

AIMuhf

Among the New features in version 885 is Fixed “Refer to Antenna” function… so lets check it out.

The AIMuhf was calibrated using the supplied OSL components and AIM885.

Direct measurement

Screenshot - 27_03_2015 , 08_54_43Above is a sweep of a 1.05m length of Belden 8262 (RG58C/U) cable (with o/c termination) attached to the AIMuhf. Continue reading AIM885 Refer To Antenna checkout

Accuracy of AIMuhf system – AIM865A vs AIM882 on a ferrite cored inductor

AIMuhfIn other posts, I have commented on the apparent inconsistency of AIMuhf measurements.

One of the devices I often wish to measure is a ferrite cored choke such as those used for a Guanella 1:1 balun. A small test inductor was made to provide a common device for measurement across instruments, and versions of software, though small, it has similar characteristics to the larger inductors more commonly measured.

Inductor1

Above is the test inductor. It comprises 6 turns of 0.5mm PVC insulated wire wound on a BN-43-202 binocular balun core. Continue reading Accuracy of AIMuhf system – AIM865A vs AIM882 on a ferrite cored inductor

LP-100A manual advice on VSWR measurement

At Where is the best place to measure feed point VSWR I discussed location of the VSWR meter and projection of its reading to another point on a known transmission line.

A correspondent has taken me to task and citing Telepost’s LP-100A manual: Continue reading LP-100A manual advice on VSWR measurement