KAMW feed setup and home-built SO-239 antenna

[Chadan]

KAMW has been online for one month! Celebrating the anniversary with some pics.

The receiver is a LLOYD'S Solid State model 9N24B-37A
Both built-in antennas were slightly damaged when I received it but it is working ok after minor repairs. Most ground and air at 122.7 for KAMW's UNICOM come in pretty clear. Being an analog tuner it is less selective than your digital receiver and picks up a small range of frequencies. Sometimes included is overhead traffic for these neighboring airports:
KBNW - 123.0 (14 miles west)
KIKV - 122.9 (20 miles south)

The current feed uses the above scanner with its built-in 5' antenna. I also have a hand-held Radio Shack Pro-97 that I'll splice in when I'm performing surgery on the Lloyd's. Its 6.5" rubber whip-style antenna does a pretty comparable job to the 5-footer on the Lloyd's.

I got interested by a few links online and decided to try my hand at building a $20 SO-239 antenna. Well, I think I'm in over $60 now and am at a point where I'm wondering how I can tune the thing. I haven't trimmed either the antenna or the ground-planes yet. Just did a rough calculation using this calculator to make a 5/8 wave antenna which came out to about 4' 9 and 1/4". The ground-planes are just 36".

The main problem I face is that when I plug the antenna into the AM external antenna jack it doesn't make much difference in the reception. The 5' built-in telescoping antenna seems to work better than this custom-built one does. So all-in-all it's been a little disappointing.

[Squawk 7700]

Chadan - Glad I inspired you to make a DIY antenna.

I added a few more photos today showing the fiberglass rods used to cover the fragile brass rods. http://www.flickr.com/photos/34848377@N07/

On your reception issue I had a similar instance where my "tuned" aviation antenna performed worse than a random whip, until I used this filter:
http://www.scannermaster.com/HPN_30118_Combined_Notch_Filter_p/24-531024.htm

If you live in a metropolitan area your scanner may be loosing it's sensitivity in the airband due to strong TV/FM broadcast stations? It was like night and day using this filter. It really made a difference.

Have fun on your antenna projects

Ken (N6GOH)
 

[Chadan]

Hi Ken! It's a great looking antenna and easy to build, but the 5' whip on my monstrous scanner is working pretty well. I live in rural Iowa so I don't suspect there is too much interference. I spent a lot more cash on this antenna than I planned to and was pretty discouraged with the results. Thanks for the link but I don't see myself spending much more on filters and the like until I am really convinced that it would be significantly better than the whip.

[Tomskii]

How far (mileage) do you reach with this antenna. My (non DIY) antenna goes aroudn 30km far but getting atc is still a now and then. (cellphone pic) http://instagr.am/p/enPAQ

Cheers,

[Chadan]

Hi Tomskii. It's hard to say how many miles out I can hear. How do you measure that which you cannot see? 

But I don't think I pick up anything further out than 10-15 miles. Their are several airports within 20-30 miles or so, but the chatter I hear is usually planes calling in their proximity to said airports when the planes are pretty much directly over my house 

And I usually cannot hear the local airport transmitting even though I am about a half mile from the FBO! I haven't messed with it in a while though.

[Tomskii]

Cheers for the reply, seems like my antenna performs better then, as I do get atc normally but depending on where I am of course it is less. I should be starting a feed soon on here as well if all goes well.

[Chadan]

good luck to ya!

[Chadan]

My reception has been boosted using a home-built Yagi antenna as described in this thread:
http://www.liveatc.net/forums/feed-setup-pictures/audio-quality-and-antenna-suggestions/msg54446/#msg54446

[ronr530]

Hi everyone,

I going to take a stab at building my own 3-element Yagi.  Just had a couple of questions that hopefully someone might be able to answer: in that PDF article the author states that he prefers wood over PVC pipe for the boom...is there a performance difference between the two?  I don't think there would be but I could be wrong.  And the other thing was regarding the elements: I scrounged around in my basement and found 1/2 inch copper pipe and some smaller diameter aluminum tubing (probably from an old antenna).  I was thinking of using the copper pipe for the driven element and the aluminum tubing for the other two elements.  I have just enough of the copper and aluminum for one antenna.   Does anyone see any issues with this plan?  If this antenna works as well as others have said, I would consider building two or three more and point them in different directions.  My wife will love me for that Any insight would be appreciated!  Thanks, Ron.

[Chadan]

Hi Ron. From the PDF referenced in the other thread:

The elements can be between 1/8 and 1/2 inch in diameter without changing performance. For the driven element you really want to use a material you can solder to.

Other than those paramaters, I don't think diameter or material is very important. And yes, wood and plastic work just as well for the support beam since they're basically inert to radio signals.

[ronr530]

Yes, that's what I thought.  Thanks for confirming.  There are a few ZBW frequencies where the ground signal is floating just around the noise level.  I'm hoping this antenna will improve that.  I'll let you know...
Regards, Ron