airtraffic

Author Topic: Variable Reception Problems  (Read 10894 times)

Offline jkaplan

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Variable Reception Problems
« on: December 04, 2006, 09:52:47 AM »
Hi Folks,

I am experiencing a frustrating problem with the EWR feed.  I am a newbie when it comes to scanner/reception issues, so please bear with me...

I utilize a radio shack discone antenna from a site located about 6 miles from EWR.  Most of the time, reception of the tower is great.  For instance, right now (9:51 EST) it is clear as a bell.  However, at times the tower is almost completely inaudible for hours at a time....

Does this have to do with weather? Time of day or night?   The difference in reception is so dramatic, yet I know that my configuration is not changing....

What am I missing?

Thanks!



Offline vz1

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Re: Variable Reception Problems
« Reply #1 on: December 04, 2006, 10:21:16 PM »
i check out the feed during and it is good i do here what you are talking about.  someetimes you can not here the planes on the ground at all and other times thay are clear as a bell.  sometimes you pick up a bleedover from from a local radio station.  i have a friend who is a continental pilot who fly the 757 and 767's.  thank you again for the kewr feed.

Offline sean

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Re: Variable Reception Problems
« Reply #2 on: December 05, 2006, 12:43:24 AM »
Jonathan,

I listened for a bit tonight and a couple of times I heard a radio station coming in pretty strong.  If it's getting into your scanner strong enough that I can hear it, it's no doubt causing you other front-end problems.   We have had pretty good luck with the AOR filters in attenuating FM broadcasters:

http://www.universal-radio.com/catalog/filters/0880.html

If you're feeling even more adventurous, try this one:

http://www.universal-radio.com/catalog/filters/0098.html

It's got a much deeper notch in the FM broadcast band, and should really do a good job at notching out the broadcast stations.  It's about double the cost, though.

That's a good start.  I'm also hearing a pretty good hum.  Send me your mailing address and I'll drop one of the isolation transformers in the mail to you.  The last one I tried on KALB helped a lot, so I'm 1 for 1 so far...  hopefully it will work for you as well.  That won't help reception, but it will make the feed a bit quieter.

Sean

Offline jkaplan

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Re: Variable Reception Problems
« Reply #3 on: December 05, 2006, 08:55:00 AM »
Sean,

Thanks for offering to send the isolation transformer... I sent you the mailing address in email.

I will check out the other components you mentioned.

By the way, I never did install the inline amplifier that I got....   I need to order a power supply for it.

However, based on what you are saying, sounds like we should do the filtering first, and then think about the amplification.  Am I correct?

-Jonathan

Offline jkaplan

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Re: Variable Reception Problems
« Reply #4 on: December 05, 2006, 09:05:02 AM »
Thank you for pointing out that the bleedover into the feed is from a radio station...  I was assuming it was from some sort of transient broadcast (mobile transceiver from an emergency vehicle etc.)...

I didn't realize that a constantly broadcasting source like a radio station could bleed into the frequency but only at certain times...  I have a lot to learn about RF communications...!!!!!!!!!!!!!!!!

Offline jkaplan

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Re: Variable Reception Problems
« Reply #5 on: December 05, 2006, 09:29:57 AM »
Sean,

Btw, I already have a ground loop isolator from Radio shack on the line.  Recall that the hum was super loud before it.....

Offline sean

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Re: Variable Reception Problems
« Reply #6 on: December 05, 2006, 08:42:42 PM »
There seems to be a lot to do up there!  Try my audio isolation transformer in place of the RS one.  I know the effectiveness of this one, so we'll be working with a known quantity.

As for the order of doing things - filter it first, then amplify it.  If you amplify first you're just amplifying noise and other interference the same amount.  We have a filter (AB125 I believe) and amplifier online at JFK.  There are some noise issues on a couple of the feeds, but I don't think that's as a result of the amp.

I'd go for the more expensive filter just because of the characteristics.  It's a much deeper notch, and will really attenuate the garbage.  Once that's inline put the amp on and you should have a major improvement.

Sean

Offline jkaplan

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Re: Variable Reception Problems
« Reply #7 on: December 05, 2006, 11:18:36 PM »
Will do.

Offline kiwisteve

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Re: Variable Reception Problems
« Reply #8 on: January 31, 2007, 05:12:55 PM »
Hi  ,I have similar problem in NZ with breakthrough from local Police repeater less than 1km away .
I'm in process of tuning a Cavity Filter to the air band .  I have some ex our old now and unused Land Mobile 101 to 108 band   now used for FM broadcast .

they provide very good out of band rejection

Steve

Offline edro20

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Re: Variable Reception Problems
« Reply #9 on: April 01, 2007, 11:56:41 PM »
I am setting up the new KLBB (almost there) feed and just got my external antenna up today. I was really looking forward to the better reception, but the opposite happened. I have a BC898T scanner and I could clearly hear airborne aircraft and tower was audible, but with static or "white noise." I could not hear aircraft on the ground except on occasion. Note: This was when the antenna was sitting on the floor inside. Now, with my discone antenna about 30 ft. off the ground and outside, everything turned to ...ya know. I did notice that I can hear radio bleed over onto the departure (119.2) freq. When I manually scan the airband freqs that I have programmed using the rotary dial, the display indicates an "AM" in the upper right corner. Is this an indication that an AM radio station is interfering? I have read the posts about getting filters, but is there a way to know which filter to get or is this just trial and error? Should I get a Jpole antenna that is tuned to the airband and effectively do the same thing? Any help will be greatly appreciated.