KLAX troubleshooting part II

[athaker]

Okay guys, so my PAR VHF-FM filter is connected, and I also went ahead and got a bigger discone antenna, going with the Diamond D130J.  It's all connected using 50 feet of RG-8 cable to a Radioshack pro-89 scanner.  To recap, I am 6 miles south of KLAX basically on Sepulveda blvd, with a few houses and maybe the 105 freeway breaking line of sight to the main airport.  Houses break line of sight to the east and I can see the Western end of the runway.

The results are far from perfect:

133.9 - North Tower comes in well.  Plane's on the ground usually break squelch, depending on their size, but definitely some static.  Planes in the sky are clear.

120.95 - South Tower is covered in static but breaks squelch and is barely understandable if my ear is to the scanner.  Planes in in the air are clear.  Planes on the ground sound better than on the north tower (they are, after all, closer)

121.65 - North Ground is readable but covered in static.  Planes about the same.

121.75 - South Ground is barely readable, if at all.  Planes come in with some static.

121.4 - Clearance delivery is unreadable 

124.5 - Socal Approach Zuma sector - i'll get back to you...

124.9 - Socal Approach Downey sector - ATC is very readable but coming in through static and planes sound good.

128.5 - Socal Approach Stadium sector - Can hear planes very well but ATC very heavy static.  Both break squelch.

127.4 - Socal Departure Katalina sector - sounds basically the same as Downey...that general hazy sound the ATC has to battle

Interestingly enough I get KSMO tower on 124.6 pretty well, with about the same light static as south tower klax.  Planes come in well too.

To conclude:

Clearly KLAX north and south have different transmitters because north comes in better than south.  If I turn squelch off, I pick up pretty much all transmissions, so they are coming in, but not cleanly.

Also, some of the static comes in waves instead of constant, as if the antenna is shaking.  I think i'm going to buy a sturdier and taller mast than the 15 foot pvc i have right now.

What advice can you dispense?  We're very close.  Do the problems above sound like something an amplifier can fix?

[LAPTOP GAMER]

Sounds like an antenna problem to me, it might not be powerful enough to get a good signal, that and ground clutter as VHF is line of sight.

[PHL Approach]

I have the same antenna, absolutely great buy. Only down side is Discones have not gain. How high is it up currently? As little as 5-10 more feet if its possible could correct the bad reception problem.

[dave]

A little more height could help, but at 6 miles out I get the feeling that there is some local interference.  Since you have the PAR filter in line, the interference is more likely power line noise.  When you open the squelch on a clear channel in the aviation band, do you hear a lot of intermittent buzz type noise or is  it constant, clear static?

Dave

[janetva.net]

WOW Dave you took the words right out of my mouth 

So I have no need to comment on that however I would like to add that it sounds like the overwellming static has got the best of ya and adding a preamp will only make matters worse !

Thats LA for ya one suggestion would be to contact a local Ham Radio Group believe me they would be more then happy to help with your FEED set up

One other thing adding a Ground to the Antenna & Radio may not help the static at VHF frequency's but it won't hurt to try  and its a good idea for lighting protection (hint)

Your doing a great service please don't give up we are all with ya on this one !

Thanks,

Good Night and Good Luck from Las Vegas, NV
Glenn KB6HLM
http://audio.liveatc.net:8012/klas.m3u

[athaker]

I do hear a very quick buzz that pops in about every 5-6 seconds, kind of cyclical...sounds like it could definitely be some kind of man-made interference. 

When I installed the new antenna I forgot to reattach the ground wire so i'll do that today.  Should it attach in between the filter and antenna or between the scanner and filter? (to what point in the line should i ground the antenna?)

And as soon as i can I'll try the extra height with a new mast.

[janetva.net]

Yep sounds like man made interference to me what you could do is try hunting it down IE:if its a power or phone line causing this the company would have to come out and fix it since they are only allowed to put out so much noise I wont get in to this here since it would go beyond the scope of this thread.


Well as for the Ground like I said it may not help but its worth a shot and it should be there for lighting protection if anything, you see there are all kinds of grounds such as (Safety/Radio Frequency (RF) /DC Grounds  just to name a few and without boring you to death with a lot of fancy terms you could just look up yourself on the net (LOL) Just ground the antenna mast and if possible the radio as well with as short and thick of a wire you can find

Here is one example of a grounded Radio Station

My radios are all grounded to a 8 ft copper ground rod drove all the way into the ground fed with a 15ft 1inc flat braided wire now this is NOT a "good ground" but it's better then nothing at all !


Glenn KB6HLM

[Unbeliever]

http://aerorfi.org/ for tips on troubleshooting real Radio Frequency Interference.

--Carlos V.