Meters vs Feet

[Deleted]

I used 622D this weekend to cut some 1/4w phasing lines of RG11. For some reason, the program only wants to deal in meters. When I entered the coax length in feet (no M at the end), it assumed it was meters. The velocity factor was something like 2.65 and the desired length was in meters. When I restarted the Stub function, the dialog box had converted the "supposed" meters into feet. I could only get it to work by entering the length in meters.

Sounds like a bug somewhere (maybe in my mind?)

73
Neal k3nc

[w9dgi]

I have also noticed the same problem -- the program doesn't want to recognize feet, only meters. If the cable length is entered as feet (no M at the end) the length is treated as meters, and an erroneous velocity factor results. Or if the correct velocity factor is put in, the result is a length in meters. It does not seem to matter whether the configuration file meters/feet line is set for 0 or 1. This is not a crippling problem because the work-around is simply to use meters for all cable measurements, but it would be nice to be able to use feet also... Thanks in advance for any suggestions or corrections!

And thanks especially for giving us such a splendid instrument! I'm delighted with its performance and ease of use.

73, Daniel, W9DGI

[Bob]

k3nc said:

I used 622D this weekend to cut some 1/4w phasing lines of RG11. For some reason, the program only wants to deal in meters. When I entered the coax length in feet (no M at the end), it assumed it was meters. The velocity factor was something like 2.65 and the desired length was in meters. When I restarted the Stub function, the dialog box had converted the "supposed" meters into feet. I could only get it to work by entering the length in meters.

Sounds like a bug somewhere (maybe in my mind?)

73

Neal k3nc

Hi Neal,

The tuning stub routine really got messed up when I was trying to "improve" it. I think it's ok now and I've uploaded a new zip file:
w5big.com/AIM_623.zip.

The units for length are specified in the config file for this routine. i.e. It uses only the default units, so entering "m" or "f" doesn't change the units in the dialog box. Whichever units are specified (feet or meters)will be displayed in the prompt for the initial cable length.

Note that the VF of the cable is calculated based on the value of initial cable length, so this length should be fairly accurate. Then the excess length to trim off will be more accurate. If the initial cable length is way off, the VF may be >1.0 or less than 0.5, so an error message is displayed then.

One of the most important features, the Excess Length wasn't being displayed at all.

Version 623 also has some other features:
Don't move cursor if the control key is pressed.
If theta goes to zero during cal with open circuit, issue a warning.
(this can occur if a long stub is in the calibration path. The warning can be disabled with a flag in the config file.)
Distance to fault should work with 1000 feet of cable.
( I'm planning to extend this range for the next version.)
Distance to Fault also displays Zo.
Changed Date format on graph to Month day, yr (instead of just numbers. It's easier to read and it's not ambiguous.)

The Application File has info on an improved short circuit cal plug. Click on "Calibration". The most recent AIM's were shipped with this improved model. It's not too hard to pull off the rubber boot to check it.

-- 73/ Bob

[cebik]

Software version 623 appears to have resolved the feet-meters difficulty. However, I am experiencing a difficulty with the loss entry in the Refer to Antenna Method B screen. The Manual specifies entry of loss at 1 MHz, which is in most cable tables. However, the screen on 623 read loss/100 (ft/m) at 30 MHz for a problem involving a frequency spread between 130 and 150 MHz. I can extract a 30 MHz value easily enough, but the screen replaces my entry by a constant 0.579.

As well, setting the .cfg file from 1 to 0 does not remove the cursor under any condition. (It is supposed to remove the cursor except when the left mouse if pressed.)

My experience is not extensive enough to know if these are real or inexperience problems.

-73-

LB, W4RNL