Close call hits from airplanes

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Close call hits from airplanes

Postby Southwales » Sat Jan 27, 2018 11:18 pm

Hi, I am quite rural in mid Wales, how common is it to get close call hits from airplanes? just had my scanner on for the last 2 hours and got 4 close call hits on different frequencies ranging from 119mhz to 140mhz, I only witnessed the last one but upon checking the close call bank the other 3 were stored in there. I would imagine being quite rural the airplanes would be at a high altitude. This is using my home made bi-cone on about 28 foot of coax. My main reason for asking is I am part way through building my 2nd bi-cone which will be about 15% bigger with more verticals, but maybe I should leave alone my original one and not disturb it, thinking if it is not broke don't fix it. What do others think?, I could maybe set this new one up along side with about a 3 foot gap as I have limited space, would having them near each other effect performance? I would not use them at the same time.
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Re: Close call hits from airplanes

Postby G4RMT » Sat Jan 27, 2018 11:52 pm

As I mentioned in one of the other topics the length of your elements won't give you more gain, it will just lower the lower frequency cutoff - that's all.
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Re: Close call hits from airplanes

Postby Minus1 » Sun Jan 28, 2018 10:27 am

Close Call hits depend upon two things:
- Signal strength (you need a strong signal for the scanner to notice the signal)
- Background noise (the more ambient radio noise there is, the less likely the scanner is to detect the signal.

It's not unusual for my scanner to detect planes taking off from my nearest airport and passing around 1km away, but it is by no means all aircraft.
You also have to consider the nagle at which the planes is turning - which may affect the signal plane.

I'd compare it with engine noise from an aircraft.
In a city you'd never hear an aircraft at 25,000 feet, but in a quite rural area such as walking in the Scottish hills, you definitely can.

Use flightradar24 to plot local aircraft and you will know exactly how high the aircraft are.
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Re: Close call hits from airplanes

Postby Southwales » Sun Jan 28, 2018 12:02 pm

Thanks for the replies, What about having the 2 antennas 3 ft apart to compare them, will they effect each other even though both will not be on at the same time?
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Re: Close call hits from airplanes

Postby m0lsx » Sun Jan 28, 2018 12:23 pm

An antenna close to metal will be effected by that metal. It's one of the reasons why lofts are not ideal places to put antennas. Potentially pipes, definitely wires, probably nail gangs, which are those metal plates used to nail joists together.
If you put two antennas close together they will interact with each other.
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Re: Close call hits from airplanes

Postby AndrewIrvine » Sun Jan 28, 2018 10:22 pm

I get close call hits from aircraft about 3-4 miles out of Runcorn that are approaching Liverpool John Lennon, also aircraft that have departed Manchester following the basic route of the Mersey toward the Irish Sea, with just my 3500 and a rubber ducky in my inlaws living room. As previously mentioned, it's not the distance that is the only factor, the signal strength is. I'm guessing also something as small as a Piper Cherokee won't fire out the same power / signal as an Airbus etc. I also live in what is known as 'The Irvine lane', small aircraft approaching Prestwick from the north west of the airport use it, as does the rescue helicopter. I can't remember when I last got a hit even though they are nearby. I get hits of the Scottish Information Broadcasts about 4 miles away on Dundonald Hill.
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