FlightAware Discussions

10190 Collinear Antenna tuning problem

Hi all,

I would like to ask a question for the specialists of this forum.
Since i am a newbie to this hobby i am giving all my best but maybe there is something i am missing and most porbably it’s “infront of me” but i can’t see it.
I recently installed a Piaware on SD system.
First i tried to use the antenna provided with the dongle but the range was …not enough (sounds familiar to you? :smile:) so i decided after some searching to make a coaxial collinear 8 section antenna out of RG6 TV cable.
The antenna range-wise was performing great although that i never got to get more than 20-35 messages/sec.
I was running a 6m thin RG174U cable from antenna but i got an advice from a friend that it is better to have a short cable to the dongle and long USB than the opposite.
I did the alteration by installing the dongle just beneath the antenna mast running just 20cm RG174U to the dongle.
To my bad surprice the things instead of getting better they got worst.
The range form 250miles got less than 80 (tested it all night) and my good old 20-35 messages/sec got out of the …window :frowning:
I was very frustrated so this morning i got up on the roof and tested agin to see if i did somethiing wrong.
I was trying some things and sudently i observed that as soon as i was holding my palm arround the base of the antenna (just were the connection of the RG6 with the RG174U is), almost instantly my range got beyond 400miles and my messages were launched to 120.
Of course as you may understand it is difficult to stay all day long up there hold the antenna as i believe that after few hours i might start getting strange side effects from radiation electromagnetic energy and the good all staff!!!
I would like to ask why is this happening and what may i install over there to simulate my hand holding the antenna. Am i missing something?
(cutting my hand and stick it to the base of the antenna is out of the question ok?
Might work with my mother’s in law hand but… :smile: :smile:)
My antenna is open end on the upper side and doesn’t have any horizontal elements on the bottom part.

I’m not an expert, but it sounds to me like you have a bad connection/ground on your antenna. May want to double check every connection to make sure they are secure. Other than a homemade RG6 Collinear and 20cm of RG174U, we have no other details to work from. What connectors are you using, any amplification, filtration, what radio etc.

Your friend was correct, 6m of RG174U would be detrimental to your signal, at least 6db attenuation using conservative numbers which equates to roughly 25% of what the antenna is seeing in the first place.

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Thank you very much Nitr0.
I double checked everything and i had a poor connection on the shielding of the RG174U. Repaired it and the miracle happened!!! Better than 90 message/sec i would see while holding it!!!

I hope you read this before chopping your mother in-law’s hand off. :rofl:
Glad you got it figured out - have fun testing!

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