05-16-2016, 04:44 PM
I need engineering help and possibly some assistance with two parts of my antenna rebuild and tower up grade project.
First of all I am trying to figure out why I can't pull the StepIR motor control cable, (a 12 wire 22 gauge cable) back out toward the house a couple of feet, then after cutting it pull it back toward the tower and pull a new cable through the 6" PVC tube. Because it was the last cable that I put in, I thought that it would be just sitting on top of the three coax cables and one rotor cable. I guess not. Maybe it just needs someone "feeding" it from one side while pulling from the other. There is one 90 degree turn underground and one 180 degree turn above ground. I guess I could just push the new cable in but I would have to figure a way to put a messenger rope or wire thru first. It is about a 75 foot run across the yard.
The other issue is with the new 432 MHz antenna. I purchased a new 2 meter beam and also a 432 MHz antenna and assembled them both. I got the SWR down to 1.1:1 at 144.200 good enough for me.
The 423 antenna I can't get the SWR under 3:1. The SWR is 3.1 at 430 Mhz and 4.1:1 at 440 MHz. I've tried everything I can think of. It matches with what Cushcraft calls their "Redi Match". We would know it as a gamma match. I tried a number of things, (beside all the way out and all the way in on the gamma match). I tried using the driven element from the dual band beam because it was a little shorter figuring shorter element higher frequency. I also tried the dual band beam's gamma match tube it is shorter. No luck. Finally a Hail Mary try. I used the gamma match tube from the old 2 meter antenna to see if I increase impedance and match the antenna no luck. The last thing I did was to take off the tower and move away to the picnic bench to see if the SWR changes and it does not.
I believe that the yagis are about 25 ohms so I would need to double that to match 50 ohms on the antenna.
Any ideas on these? Perhaps if someone gets on the 6 meter net tonight they can ask and see if anyone has any ideas. The 432 antenna is only 4 feet long and two screws it's off the tower. I could take it someplace if someone can help.
Any ideas on either please email me here or at my regular email address.
Thanks
AL N1APi