Quick and dirty (but extremely effective) longwire antenna - Printable Version
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+--- Thread: Quick and dirty (but extremely effective) longwire antenna (/showthread.php?tid=1021)
Quick and dirty (but extremely effective) longwire antenna - Ron Ramirez - 03-10-2008
I've been wanting to run a longwire antenna to my workbench for quite a while now.
I even acquired a large amount of coax, which I intended to use as a lead-in.
My intention was to run a long wire from the eave of my house on the north side of the house, well away from the power lines, to the roof of the garage, and then use a coax lead-in to run the length of the basement, over to my workbench.
I don't have to do that now.
Last year, I pulled the plug on land line phone service for good - I now use only a cellphone.
Guess what? The disconnected phone line still exists outside...and I happen to have a phone jack next to my workbench.
SO...
First of all, I measured the telephone terminals to make absolutely sure there was no voltage on any of them (there wasn't).
Then, I soldered one lead of a .01 uF capacitor to a long piece of wire. Connecting the other end of the wire to a radio I had on the bench, I then took the end with the capacitor, having removed the cover from the phone jack, and touched the free end of the capacitor to the various screw terminals (red, green, yellow, black).
While every terminal improved performance, the greatest increase came with the capacitor connected to either the yellow or green terminal.
I then screwed the free end of the cap to the green terminal.
The set on the bench, a Philco 71, was then receiving signals literally all over the AM band.
My next move will be to acquire a cord with a modular plug so that I can connect the cap to the green wire on this cord, and then plug the modular plug into the phone jack. That way, I can quickly disconnect it when not in use or in the case of an oncoming thunderstorm.
I do not recommend doing this if your phone line is still "live" and in use. But if you have thrown AT&T out of your house, as I have, this is something worthy of consideration.
Coax lead-in - AI2V - 03-10-2008
Too bad my landline connections are still live.
One thing to add about coax lead in- if it is connected from ANT to GND, the coax capacitance will be in parallel with the input tuning circuits and drastically reduce reception (been there, done that). However, is you use a simple ferrite ring transformer of perhaps 5- 10 turns wound bifilar, and connect that to the balanced input, the reception is outstanding! -Pete
- Ron Ramirez - 03-10-2008
Hi Pete
Oh yes, I was aware of the ferrite balun...and had planned to use one when I constructed a longwire...but now, I don't have to worry about it.
Thanks for mentioning that, though. 
- Jim Dutridge - 03-11-2008
I still have active outside phone service here but I've been using their lines as an antenna for quit some time. I'm just tied in thru a .o1 MFD ceramic and it works great. Only drawback is if I leave a radio connected to it there is a terrible buzz on the phone. Just have to remember to disconnect the radio when I'm done.
- TonyJSenior - 03-11-2008
I'd like to give that a shot as well except that my DSL service rides on the same phone circuit as my landline. Wonder if that would cause a problem with either?
- Ron Ramirez - 03-11-2008
Hi Tony
Yes, it will cause problems with both, as Jim mentioned...which is why I do not recommend doing this with a live phone line.
*****
I checked out my telephone network interface box this afternoon. Obviously Ma Bell disconnected my line at the utility pole, because the wiring is all still connected inside the interface box. I pulled the modular plug from the network interface jack...reception went way down...reconnected it...reception came back up.
The phone line runs some distance to the utility pole. So I now have a very good longwire!
- TonyJSenior - 03-11-2008
When I get some time I'll check my network interface and see if they have the yellow and black pair terminated from the drop as I know that it is brought from the interface into my basement and unused once landed there. Maybe I'll get lucky with that pair. I assume that this longwire will be good for shortwave as well?
- TonyJSenior - 03-11-2008
I just had a thought...I usually put about 75' worth of Christmas lights along the gutters on the front of the house. If I leave them up all year unplugged and run a lead in wire from there to my radio...
- Ron Ramirez - 03-12-2008
Hi Tony
In my interface box, the yellow and black leads which go inside the house were not connected to anything; they were just dangling free. This is not surprising, though; for many years now, Ma Bell has only used two wires for POTS (plain old telephone service); green (tip) and red (ring).
The Christmas light string might be worth trying...IF you can be sure that no-one plugs the string into 120 VAC when you're not looking!!!
- planigan - 03-13-2008
That is interesting about the phone lines. Many times the lead in line from pole to house has more than two or three pair. In my area which was built 30 years ago, I believe we have 4 pair. They may have done that as mine are underground and obviously useless for antenna use. However you could check at the entrance box and see if you have unused pairs as they are not connected at pole. The extra, unused lines could be utilized for the antenna. Oh and by the way TonyJSenior, you would do anything to get out of taking the Xmas lights down woudn't you. PL
- TonyJSenior - 03-13-2008
The lights and outdoor decorations can be a pain to put up and take down that's for sure. I was talking to my neighbor about this and we thought it would be a neat idea to have rotating soffits on the roof overhang. The lights would be permanently attached on one side, the other finished with just the siding material. When the holidays come around, push a button and the lighted side rotates out.
Well, I didn't say it was a feasible idea
- planigan - 03-13-2008
Tony, when you get the first protype made I'll test it! PL