[amsat-bb] Mounting Coax feed lines to Az/El rotator

[Patrick Dohmen]

Hey all,

Nearly one year ago I installed two cross-yagis on a Hummel Teletower 
with a YAESU G5400B rotator system. I have made a lot of thoughts on how 
to "wind" the coaxial feed lines around both: the azimuth and also the 
elevation axis. With elevation I am very fine, but maybe this is just a 
matter of time as it seems to be with azimuth!

Some days ago I found some flipping faint/strong signals on my SatNOGS 
station (https://network.satnogs.org/stations/37/) in the 2m band. First 
I thought this could be some kind of frontend-overloading with the RF 
amplifier, but it turned out: this is not!

Today I ran some tests while driving the antenna with my YAESU FT-847 at 
minimum output power (around 1.5W). I could see that with elevation 
rotation everything is fine from 0° to 180° el. Then I tried to turn the 
azimuth and - guess what? - SWR "jumps" at around 270° from 1.1 to >4! 
That truely indicates a broken cable.

As I installed that wires, I made a short connection of flexible coax 
cable (HIGHFLEXX 7) from the phasing line box, down the mast and made a 
connection to ECOFLEX 15 running into the shack. The flexible lines are 
"wrapped" around the azimuth pipe with a radius of around 30cm. I am not 
sure, but it could be broken just on top of the N-connector... Do I need 
to somehow support that short piece of wrapped line?

Any hints on how to mount the cables to prevent this are really appreciated!


Kind regards,

Patrick, DL4PD