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Air Traffic Monitoring => Feed Setup Pictures => Topic started by: Sirclown82 on July 12, 2005, 01:04:58 PM

Title: DFW East Towers Setup
Post by: Sirclown82 on July 12, 2005, 01:04:58 PM
The radio is a RadioShack PRO-2053 and the funky looking antenna is a VHF J-Pole. The antenna is designed for Amateur Radio use but it just receives so good on just about everything.
Title: DFW East Towers Setup
Post by: Jason on July 12, 2005, 01:15:38 PM
The J-pole looks nice.  Did you make it yourself?

What coax are you running?  Belden 9913?  RG8/U?

Also - is that currently where the J-pole sits for the feed?  If so, any chance of getting it higher?  That will likely improve reception and take some interference out of the sound.
Title: DFW East Towers Setup
Post by: Sirclown82 on July 12, 2005, 01:34:15 PM
I had help, Well actuall i supplied the parts and a friend cut and built the antenna. It is a stainless steel pipe so it wont rust and it's tuned for a straight match for my scanner.
I am using RG-8X because it has a stranded core instead of a solid core. I would like to get the antenna higher but my apartment complex wont let me get it any higher than that without a $10,000 liability insurance policy on it, but it does a pretty good job at ground level. Thanks.
Title: DFW East Towers Setup
Post by: Jason on July 12, 2005, 01:52:32 PM
Quote from: sirclown82
I had help, Well actuall i supplied the parts and a friend cut and built the antenna. It is a stainless steel pipe so it wont rust and it's tuned for a straight match for my scanner.
I am using RG-8X because it has a stranded core instead of a solid core. I would like to get the antenna higher but my apartment complex wont let me get it any higher than that without a $10,000 liability insurance policy on it, but it does a pretty good job at ground level. Thanks.


Stainless steal?  Never heard of that before.  Always heard of J-poles made of copper or twin-lead (mine is made out of copper)

The RG8 is very good coax although nothing can really beat that Belden 9913.
Title: DFW East Towers Setup
Post by: Sirclown82 on July 12, 2005, 02:05:20 PM
You can use stainless or copper. Of course copper has just a little bit less resistance than SS, but stainless doesnt corrode. As long as it's tuned at 50 ohms, RX/TX shouldn't be a problem though. I have had this antenna for 6 years now and still looks almost brand new.
Title: DFW East Towers Setup
Post by: Jason on July 12, 2005, 02:08:16 PM
Quote from: sirclown82
You can use stainless or copper. Of course copper has just a little bit less resistance than SS, but stainless doesnt corrode. As long as it's tuned at 50 ohms, RX/TX shouldn't be a problem though. I have had this antenna for 6 years now and still looks almost brand new.


Ok...I picked copper so it actually would weather and blend in with my roof.  Like you said; it's less resistance; so a little better signal; but not a major difference.

Neat stuff  :lol:  8)
Title: DFW East Towers Setup
Post by: Sirclown82 on July 13, 2005, 11:11:23 AM
Im working on a new antenna. I want to get a Diamond D130J Discone antenna.

http://www.rfparts.com/diamond/d130j.html

I've heard alotta good about these.
Title: DFW East Towers Setup
Post by: Jason on July 13, 2005, 12:27:45 PM
Quote from: sirclown82
Im working on a new antenna. I want to get a Diamond D130J Discone antenna.

http://www.rfparts.com/diamond/d130j.html

I've heard alotta good about these.


They are good antenna's but keep in mind that the J-pole offers a few (I believe 3dB's also dependant on setup) dB's of gain, while the Discone does not.
Title: DFW East Towers Setup
Post by: Sirclown82 on August 18, 2005, 06:42:08 PM
Your gain comes from the Transmit side of the antenna. You can use discones to transmit, thats were the negitive gain comes from, but they are very good RX'ers because if the wideband capabilities.

Just an update.

Now my J-pole has gone nutts. The impedance has changed and gone wild. I have no antenna analyser to correct this little hassle. I am trying to come up with a temporary concoction just to keep DFW on the air. :)
Title: DFW East Towers Setup
Post by: Jason on August 19, 2005, 04:24:49 PM
That stinks Chris.  Didn't you say that your J-pole was tuned for the 146MHz band?

Jason
Title: DFW East Towers Setup
Post by: Sirclown82 on August 19, 2005, 05:57:13 PM
Yes 146 is it, but the impedance should be tuned for 50 ohms. If that gets outta wack you start to get a loss at the antenna/coax connection, long before the signal thinks about getting to the receiver. I had to go to my local radioshack and get a CB antenna and cut it to the correct length for 126.55. I had to cut the whip to 4' 7 1/2" which is a 5/8 wave antenna :D, and now i can hear the tower clearer than i have ever heard it before from my house.

Here is a shot of the temporary antenna i had to come up with. It is a magnet mount base with a 4' 7.5" whip mounted on a pizza pan. The pizza pan acts as a ground plane, just like if it was used on a car. If you ever needed to use a mag mount antenna, thats a little secret for you, Stick it to a pizza pan atleast 12" round.
Title: DFW East Towers Setup
Post by: Jason on August 19, 2005, 07:19:18 PM
A very creative, working antenna.  Great job!!!
Title: DFW East Towers Setup
Post by: Sirclown82 on September 03, 2005, 12:53:20 AM
ScreenShot of the Laptop running StreamTranscoder and Goldwave to record the feed non-stop. I wait for emergency traffic, which usually happends atleast once a day, so i can get a realtime recording using Goldwave then i can modify the clip and then save it as an mp3 file to sumbit to this site. I set it to record on VOX so there's really no dead airtime on the playback.
Title: DFW East Towers Setup
Post by: Jason on September 03, 2005, 09:39:38 AM
Nice setup of programs there, Chris.  Looks like you have your own operation going there :-P