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| | |-+  KLAX...Troubleshooting time...All feeders read!
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Author Topic: KLAX...Troubleshooting time...All feeders read!  (Read 8010 times)
athaker
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« on: August 06, 2007, 12:54:19 AM »

Esteemed community,

Thanks to Peter, I now have the basic equipment to provide a KLAX feed.

He sent me a discone antenna (a smaller version than the one I see in the radio shack picture, with less "spikes"), an RG-8 cable 50', and a Radio Shack pro-89 hand held scanner.

I bought a long pvc pole (sturdy enough, for now) as a mast to extend just above the roof of my place, and the antenna is mounted on top.

So, I plugged it all together, printed out the KLAX frequencies, and fired the sucker up.  A warmth filled me when immediately a Southwest flight reported himself established on 24R, nearly crystal clear.  To my dismay, however, the tower came in broken. Messing with the squelch, trying the ground and ATIS frequencies, and listening for a while, I concluded that we are faced with our first problem:

I can hear planes, but airport transmissions are not coming in clear.

And so, I appeal to you, the experienced and wise, for possible solutions.

Some of the first things that came to mind are a bigger discone or delving into some of those scanner peripheral.  What do you guys think?
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cactushp
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« Reply #1 on: August 06, 2007, 02:39:54 AM »

Do you have line of sight?
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Scott Mulhollan
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blizzard242
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« Reply #2 on: August 06, 2007, 03:07:11 AM »

I have several suggestions, first line of sight (what is between you and the airport), what was the weather (weather conditions can greatly affect radio transmissions it really is a black art, rain and fog will have the most affect along with temp and some unusual atmosphere effects once picked up a plane over 100 miles away). Lastly is your antenna tunable, and do you have it correctly tuned. You get better line of sight to plans so it is a little more forgiving, but the much weaker ground transmissions are much more finicky.
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Lezam
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« Reply #3 on: August 06, 2007, 09:55:27 AM »

Maybe try to ground your scanner? Get an old telephone cord, or whatever kind you would like and strip the two ends. Connect one end between the scanner and the cable joint, and connect the other end of the cable to something metal like your computer. Make sure the wire is securely touching metal on either side.
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KSYR-pjr
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« Reply #4 on: August 06, 2007, 11:59:01 AM »

Given that the antenna and cable (but not the scanner) were providing good tower and approach ATC signals for the SYR feed, I would recommend verifying that the antenna cable and antenna itself are not near an electrical source.  Be sure the cable is not running parallel to electrical lines in your house, nor near fluorescent lights.

How about non-home interference?  Any large radio station antennas between you and the airport? 

FYI, the SYR feed is about 9 nm or so from the airport and there is a slight ridge between the airport and the feed's receiving antenna.   I wouldn't call what I have as perfect line of sight to the airport from the receiving antenna's elevation.
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Regards, Peter
ATC Feed:  Syracuse (KSYR), NY
KSYR-pjr
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« Reply #5 on: August 06, 2007, 12:02:32 PM »

Lastly is your antenna tunable, and do you have it correctly tuned.

As far as I know the antenna in question is not tunable, as it is one of those stock Radio Shack discone antennas.
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Regards, Peter
ATC Feed:  Syracuse (KSYR), NY
athaker
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« Reply #6 on: August 06, 2007, 01:05:12 PM »

OK, so, here are some answers to your questions:

Line of sight-

I am about 7 miles due south of the approach end of the 24 runways, basically along Sepulveda Blvd.  Unfortunately, there is a house due north of me (my next door neighbors), and it just barely blocks my line to the eastern half of the airport.  The western half, however, is a clear shot, except for a row of trees and probably some 1 story homes that line the southern end of the airport along the Imperial Highway.

As soon as the aircraft on the 25's leave the ground, I can see them, usually well enough to make out the aircraft type.  I cannot directly see any airport structures, and do not know where the airport signals are transmitted from (it's not usually the tower itself, is it?)  I see a tall building and it might be the tower, but i'd think i could tell the shape from far away, and don't have binoculars handy.  It's probably something else.

As far as I can tell, there are no ridges or hills blocking me, since I'm mounting this thing from the balcony railing of the top of a three story townhouse perched on a hill, but my immediate community results in a few homes to block my northeasterly views.

Electronic equipment-
The cable I'm using comes straight down from the mast that extends about 6 feet above a balcony railing, which is directly above my room.  It's not well secured yet, and comes right through my window to a scanner, which will be under my bed.  I think at most, it's a 25 foot run, but I'm using the 50' cable, so the excess is just bundled.  No huge EM fields being created in that short distance, except for a couple of outlets in maybe a 5 foot radius.  Nothing to cause crazy distortion i don't think.

Other EM sources-
I live in the LA area, so the airwaves are basically saturated.  No large radio stations between the airport and I, but definitely some within a 20 mile radius, and many many within a 30 mile radius.  There are also some police and fire dispatch centers nearby.  I thought the other day I might have heard music carrying on the ATIS frequency, so perhaps a filter will clean up the feed a little.

---------

I'll definitely try grounding the thing.  And yes, Peter's antenna is not tunable, and it worked fine for him at KSYR, as he mentioned.  Weather wise it's been overcast the past couple of days but nothing ridiculous.

Keep the tips coming guys.  Thank you, and I'll look into what you've said so far.







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BerendBotje1
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« Reply #7 on: August 06, 2007, 03:06:10 PM »

Perhaps a wild shot but who knows.  cool
To eliminate a broken cable during transport or whatever you might try to use the "rubber duck" antenne provided with handheld scanners. I don't know if it came with "the package" but it's worth a try. Get the handheld up to the highest point of your place and listen out the freq's.

Grtz David
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KSYR-pjr
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« Reply #8 on: August 07, 2007, 12:21:17 PM »

Any luck with this over the last day, Adarsh?   
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Regards, Peter
ATC Feed:  Syracuse (KSYR), NY
dave
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« Reply #9 on: August 07, 2007, 01:04:01 PM »

Perhaps a wild shot but who knows.  cool
To eliminate a broken cable during transport or whatever you might try to use the "rubber duck" antenne provided with handheld scanners. I don't know if it came with "the package" but it's worth a try. Get the handheld up to the highest point of your place and listen out the freq's.

Grtz David

Definitely a wild shot.  Those antennas are pretty close to dummy loads.  smiley  Definition of a dummy load is left as an exercise to the reader.

Dave

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LAPTOP GAMER
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« Reply #10 on: August 07, 2007, 01:20:11 PM »

Dam I hope this works a she is our only shot at KLAX tower right now.
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athaker
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« Reply #11 on: August 07, 2007, 01:41:45 PM »

Dam I hope this works a she is our only shot at KLAX tower right now.

I hope you meant "as he" laptop gamer...  grin  j/k

You know, i've been at work since yesterday (24 hour shift), but when I get home tonight i'll muck around with it some.  Only thing I can really do right now is to perhaps reposition my antenna and ground the assembly, so we'll see if that works.

Peter wrapped his equipment nicely so the cable is not damaged or anything like that.


Whats next?
Maybe try to get a notch filter or signal amp?
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LAPTOP GAMER
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« Reply #12 on: August 07, 2007, 02:33:38 PM »

oops sorry my bad, I meant he.
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KMSY
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« Reply #13 on: August 07, 2007, 02:37:58 PM »

oops sorry my bad, I meant he.

It made me think for a while, then I figured you were talking about the J-Pole. I call mine Betsy  wink.
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KSYR-pjr
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« Reply #14 on: August 07, 2007, 02:57:26 PM »

It made me think for a while, then I figured you were talking about the J-Pole. I call mine Betsy  wink.

LOL!   

I was also struggling with his sentence but ended up giving up.   
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Regards, Peter
ATC Feed:  Syracuse (KSYR), NY
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