Refer To Antenna

[wa1fxt]

Bob,

I am trying to establish a set of calibrated cables for my AIM. So, I used the Calibrate > Cable function to establish .CCAL files. I calibrated over the range of 1 to 170Mhz so the cables could be used anywhere within that range.

However, at the time I want to use the cables using the "Refer to Antenna" function and I only want to set the limits to 144 - 148MHZ., the .CCAL file for that calibrated cable sets the limits at 1 - 170Mhz. If I try to change LIMITS, the .CCAL file disappears from the screen and it appears that I am no longer in the "Refer to Antenna" mode. The work around of course is to recalibrate the cable for 144 - 148Mhz. This can be frustrating and destroys my desire to have a set of calibrated test cables that will work over the whole range of the AIM but, using subsets of frequency limits. If I have to recalibrate my standard test cables for every frequency range. I'll have a zillion .CCAL files eventually.

Is there not a way to calibrate a test cable across the whole AIM range and then pick a subset of that range for the scan limits at the time a test run is done? That would leave me with just a limited number of .CCAL files for each test cable.

Might be a consideration for the future.

73, BOB WA!FXT

[Bob]

wa1fxt said:

Bob,

I am trying to establish a set of calibrated cables for my AIM. So, I used the Calibrate > Cable function to establish .CCAL files. I calibrated over the range of 1 to 170Mhz so the cables could be used anywhere within that range.

However, at the time I want to use the cables using the "Refer to Antenna" function and I only want to set the limits to 144 - 148MHZ., the .CCAL file for that calibrated cable sets the limits at 1 - 170Mhz. If I try to change LIMITS, the .CCAL file disappears from the screen and it appears that I am no longer in the "Refer to Antenna" mode. The work around of course is to recalibrate the cable for 144 - 148Mhz. This can be frustrating and destroys my desire to have a set of calibrated test cables that will work over the whole range of the AIM but, using subsets of frequency limits. If I have to recalibrate my standard test cables for every frequency range. I'll have a zillion .CCAL files eventually.

Is there not a way to calibrate a test cable across the whole AIM range and then pick a subset of that range for the scan limits at the time a test run is done? That would leave me with just a limited number of .CCAL files for each test cable.

Might be a consideration for the future.

73, BOB WA!FXT

Hi Bob,
Right now the ccal data is not interpolated, so the file has to be generated for each set of scan limits. I'll try to generalize this in the future so you won't need a file for each set of limits.

73- Bob

[jbmcl]

I was about to make the same post as I want to add a "known" cable or so to the bag.

As an idea, instead of interpolation, perhaps a LARGE, calibration file with points close enough that the nearest one would be good? Of course the scan time for the cable would be much longer, but would not have to be repeated for each use. Another possibility - compute a "best guess" for the cable characteristics and pick it up like as in specifying the cable. Not as accurate of course, but probably covers a pretty good set of tasks. Having to re-calibrate for each scan pattern is a slight nuisance!

Jim - W4YXU

[Bob]

As an idea, instead of interpolation, perhaps a LARGE, calibration file with points close enough that the nearest one would be good? Of course the scan time for the cable would be much longer, but would not have to be repeated for each use. Another possibility - compute a "best guess" for the cable characteristics and pick it up like as in specifying the cable. Not as accurate of course, but probably covers a pretty good set of tasks. Having to re-calibrate for each scan pattern is a slight nuisance!

Jim - W4YXU

Hi Jim,
The "best guess" approach you mentioned corresponds to ref method B where you specify properties of the cable without having to actually calibrate it. This is good for any frequency range. This works pretty well if you have good quality cable with accurately known characteristics.

73/ Bob