Hi Bob, I have been using the AIM4170 for some years now but I have reason to suspect my custom calibration procedure may be wrong. I use a length of RG super8 as the connector to test and experimental antennas for HF. I have calibrated this cable from 3 to 30MHz with delta frequency of 0.1MHz. I have used this cable when measuring and recording the SWR/Z characteristics of a magnetic loop in the HF bands 14 to 28MHz. On rereading the calibration instructions I note that a small delta f should be used but if I go to a delta f of 0.01MHz this would result in 3000 cal points. The instructions indicate a maximum of a 1000. My question: is a delta f of 0.1 adequate if there are no filters involved.
This reminds me of a suggestion that I meant to make some time ago. When custom calibrating a coax cable for the HF bands, I have up to now done a separate custom calibration for each of the bands -- this is OK, but it means typically 13 separate calibration runs (one for each band, 4 for 10m).
Now that the data storage limit is increased to 30,000 items, this would mean I could calibrate the cable from 1-31MHz in one go, with a frequency step of 1 kHz. However, when viewing a subsequent custom scan, I would only be able to see the whole 30MHz range. Is there any possibility of adding a zoom feature that lets you zoom into any sub-range of interest?
Hi Ian, There isn't a zoom feature per se but you can select a sub-range of the custom cal range and rescan to get better resolution in a particular band. You can have one large cal file to cover all the bands. Then you don't have to reload cal files when changing bands.
When scanning a multiband antenna, you can use the Band Skip mode to skip over the unwanted frequencies for faster scanning. The skipping is determined by the band definitions in the config file, which can be customized for particular applications.
I am laying claim to the most southerly use of an AIM uhf so far, here in my work in Antarctica (64South). I am VERY pleased with its operation. Measurements which used to take hours are done in minutes now. My understanding of theory has improved greatly in the short time I have been using the analyzer. Thanks for such a great device!
On today I received my AIM uhf and a few hours of having, it helped me to solve a problem. I was in the process of tuning an antenna in the FM commercial band and everything was perfect with the antenna at low height, but when this was raised my other analyzer gave erratic readings from the influence of two local radio stations (this gave me a tremendous confusion, because I thought it was an antenna problem).
Once I familiarize a litle bit with the AIM uhf, I determine that the antenna was properly and have a new approach to the problem, it was a new amp that was testing (works great with dummy load!), and since it see a reactive load even with a few watts out it begins to protect itself )
I put the other amp and everything perfect! ...... a wonderful start.
We will probably stick with the present interface on the AIM4170 and PowerAIM120. The AIMuhf does have a usb interface.
The VNA2180 is a two port instrument. It can handle a larger interfering signal than the AIM4170. It goes up to about 2V on the input (the PowerAIM goes up to 25V). The VNA2180 is like the AIM4170 on Port A, so it's good for measuring antennas as well as filters. The VNA2180 can also be used with an external multiplexer which helps when tuning antenna arrays.