Radio > Antennas
Something I do not understand on antenna "Cutting & Tuning"
Tempstar:
Dead on Ghrit! And yes, most modern tuners have no problem with 75 ohm feedline. I use 1604 Belden video cable to my Chameleon and it gets a better match than with 8X.
spacecase0:
I have seen an old way of tuning that seems very accurate,
you make a wire loop that sits on the antenna, it is connected to a small light bulb.
you slide it along the antenna till you find the null point where the light is dimmest, and you cut the wire at that point.
Tempstar:
Edit: 1694 Belden cable. I hate typing in the dark.
DragoSapien:
Im here!!!!!! Just reading and learning what you all are teaching. 8)
BTPost:
The way “The Big Boys” do this is to put a Impedance Bridge on the feedline at Tx Antenna Port, and the tune the antenna by observing the resonance of the whole Antenna System... When I was designing and installing multi Band HF Marine Coast Station Antenna Systems, I use my Cushman CE5A with Tracking Generator w/Spectrum Analyzer that had an Impedance Bridge that connected the Signal Generator & Spectrum Analyzer on opposite Ports and the Antenna in Question and a 50 Ohm Load on the other two Ports... I could see the exact Resonance Frequency Point and then watch how it changed when an adjustment was made, then I could calculate how much adjustment would be needed to get the resonance point where it needed to be for that band... On Trapped Antennas, you do the Higher Frequency Band, first, and work your way down for each lower frequency band.... I designed and built many muti-KiloWatt, Multi Band Antenna Systems, over the years...
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