Did you buy it or build it? Looks very professional.Throw away the 300ohm ribbon and the transformer (4:1 balun ?). Disassemble the rabbit's ears and join the coax cable to the telescopic elements at the base. Re-assemble. Run the coax to your receiver. Set the lengths of each rod to a quarter-wave for you frequency of interest.
A 300ohm antenna is usually a loop like mine. The 300:75 balun is in the orange box . Works well on the 118-136MHZ air band.
View attachment 106566
See pix above.Tuner wheel? So that implies that there are some other components in that rabbit ears antenna set (coil / cap maybe). May be helping, but might also be reducing your signal. You write that the rabbit ears give you better (stronger) result than the Comet 100, so you might benefit by following the instructions in the RR Wiki for the Homebrewed Off-Center Fed Dipole (linked previously). Use the 300 to 75 ohm transformer (or get another... they're inexpensive) and make the "wire version" shown in the Wiki. Hang it vertically in the highest window you can (or attic). Run the coax away at a 90 degree angle to the two vertical antenna elements.
Popnokick,Look again at the pics in Wiki page for an Off-Center Fed Dipole Homebrewed Off-Center Fed Dipole - The RadioReference Wiki
Notice that the two antenna elements are in a straight line running away from each other... not in parallel as in your TV antenna pic. Your TV antenna as it's presently configured is probably closer to a J-pole... which is going to make it very narrow in frequency coverage. So you have two options: 1) Get a new 300 to 75 ohm transformer and some wire for about $15 at any hardware store or Walmart and make the OCFD as described on the RR Wiki page; or, 2) as majoco suggested, make a dipole tuned for the aircraft band by ditching the 300 to 75 ohm transformer entirely and connecting the coax directly to the antenna elements. HOWEVER, you will still need to have each leg of the dipole vertical and running away from the other at 180 degrees, not in parallel to each other. Based upon the pic of your existing TV antenna it doesn't appear that is possible.
The advantage to option 1 (OCFD) is that it will be useful across a wide swath of frequencies that can be received by your scanner. The dipole is going to operate best in the civil air (118-136 mHz) band, and may give you some reception on other frequencies but not as efficiently as the OCFD.
Wire - Any wire will work. "Bell" wire, THHN, automotive primary wire, etc. If you go to one of hardware chain stores (Home Depot, Lowes, etc.) just go over to the "wire cutting area" in Electrical. Typically they have a bunch of random lengths lying around of various types of single conductor wire in the cutting area. (Two-conductor wire is OK too, but short the ends together when you connect so it all is electrically a single wire.) In a box or bin near the cutting area they'll have those random cut pieces wrapped in tape with a price on them. You need at least 66 inches... buy a little more in case you make a mistake measuring.Popnokick,
The wire version of the homebrewed off-center fed dipole sounds like the way to go.
For nearly 5 decades I wrote about science, tech, and medicine from a layman's point of view, and my "big trick" was being unafraid to admit my ignorance.
Sooooo . . . when I go to the hardware store,
- what sort of wire should I buy?
- what, specifically, should I ask for when I want the transformer (I plan on calling before I go to the store)
- and the lugs . . . just ask for lugs?
For a feedline, a plan to use the one that is currently connected to the rabbit ears antenna.
BTW, thanks for your help!
I've noticed that my local ATIS signal varies somewhat in strength, listening with the same radio, same antenna, same location, etc. . . . I don't know why.for me, the ATIS signal was the hardest to catch, I was receiving lots of airband traffic, got the antenna 28ft up in the air and am able to receive the local ATIS , which is less than 5 miles away as the crow flies
Google maps tells me I am 7.8 miles from Albany (NY) International Airport. The "Amazing Color Supreme II" rabbit ears antenna brings in ATIS at two bars on the signal strength meter.this is the thread I landed on when first trying to receive our ATIS
Hi, Have a new Uniden SDS 200 scanner. Live fairly close to Hanscom AFB (Bedford, Mass.) and about 15 miles from Logan Airport (Boston). I can hear lots of Tower comms, Tracon, etc. from both. But, If try to pick up any ATIS from either, nothing but continuous static. Was wondering: Have...forums.radioreference.com
What I have seen written here on RR... but no test data produced or shown... is that the larger diameter of the elements (copper pipe) will produce a greater bandwidth in each of the resonant "sweet spots" of the OCFD antenna. There's a project for someone (comparing bandwidth of various copper pipe diameters on the OCFD). There is no requirement to paint the pipe... mine is bare copper. But it is in the attic so I have no need to paint it. However, it could be painted with any non-metallic content paint once it was assembled and all the electrical connections secured. There are MANY threads here on RR regarding painting antennas and what paint to use. Search is your friend.for the HOCFD antenna, what is the frequency range (bandwidth) for the 48" x 18" model using 1/2" or 3/4" copper pipe? And you DO paint the pipe, no bare copper?
That was me, I posted that way back in March, 2006 Indoor Scanner AntennaSomeone here on RR posted that they had repurposed an old TV rabbit ears antenna for monitoring air frequencies and that it worked pretty well (If I could find the post again, I would reference it). If I recall correctly, they adjusted the rabbit ears until each was about 18 inches long. I look up online, and a quarter-wave of 128 MHz is around 19 inches. Close enough.
Hmm, I thought, I've got an old rabbit ears antenna somewhere . . . I found it; a ham friend (thanks, Steve!) whipped up a jumper cable to connect the rabbit ears to the BNC connector on my SDS200, and -- voila! -- we're in business. I figure the ATIS signal at Albany Country Airport will work just fine as a reference signal, so I lock the SDS200 onto that. The indoor antenna I am using for the SDS200 is a Comet W100RX, extended to its full length, about 40 inches. The signal strength meter is showing just one bar.
I hook up the rabbit ears (set to 18 inches long) to the SDS200, and the ATIS signal is immediately worse; no bars. Making sure the switch on the antenna is set to VHF, I try clicking the dial for various VHF settings on the rabbit ears antenna. No improvement, and some positions are noticeably worse.
As I am putting the Comet antenna back on the SDS200, I notice that there are markings on the black barrel of the first segment of the telescopic antenna. One of them says "VAIR," and it indicates that the W100RX should be extended 5 1/2 segments to receive VHF air frequencies. So I try that and -- ta da! -- the SDS200 shows two bars on the ATIS signal. Cool! I measure the length of the Comet antenna at 5 1/2 segments, and it's 27 inches to the right-angle bend where the BNC is connected.
So maybe the rabbit ears need to be adjusted to 27 inches. I try that, and it works no better than before.
That 27 inches looks kinda familiar, though, so I measure the stock telescopic antenna that comes with the SDS200, and it is almost exactly 27 inches. I connect that antenna to my Uniden 125AT, and it, too, shows two bars of signal strength on the ATIS frequency (and that's better than my Diamond 77 antenna). Very nice . . . an improved setup for listening to civilian air frequencies on two scanners.
But now here is the question: why should a 27-inch antenna work better? It's not -- as near as I can tell -- quarter wave, or half wave or five eighths wave. It is approximately 3/8 wave.
Can someone please shed some light?
Greg,That was me, I posted that way back in March, 2006 Indoor Scanner Antenna
I had simple rabbit ears like this: https://i.ebayimg.com/images/i/161269129068-0-1/s-l1000.jpg,
not the high end model like yours (I remember that one from when I worked at Radio Shack, wow, the Archer brand), I was using the ones that came with my TV
I was trying to DIY the Grove Enterprises indoor antenna, so I extended each whip to 33" since the total length of the Grove was 66"
I didn't know anything about antenna theory yet, so I wasn't looking at quarter-wave or half-wave, etc
I was just trying to improve my reception on a very tight budget