I recieved my Par EF-SWL today and have a ground question. In the instructions it says to keep the ground wire as short as possible. I plan on running this horizontal about 5 feet over my roof wich will make my longwire about 25 feet up. This would make my ground wire 25 feet also. Should I run it in some schedule 80 PVC or something to try to shield the ground wire? Also would my house service ground rod work fine or should a separate ground rod be sunk for this. I would like to get the longwire up before my Icom R75 arrives Friday so I have the weekend to play! Thanks in advance, Nick
Par Longwire
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I'm not familiar with that antenna, no idea how 'long' it is. If the feed point of the antenna is 25 feet in the air and you have to run a ground wire that 25 feet to a 'ground' (the service rod should work), then that 25 feet of ground wire becomes part of the antenna. The antenna is then 'two sided', it isn't really a "longwire" anymore, but an off center fed doublet. The length relationship between the two sides of that antenna will have a definite affect on it's input impedance. But since you'll be using it only for receiving, that impedance value isn't exactly a huge biggy. What will make a difference is how the two sides of that antenna affect it's radiation pattern (or reception pattern, they are reciprocal).
One alternative is to put the feed point at the service ground, and then string the thing as hig as you can get it. That would certainly keep the length of the ground wire short. But, it will also have a detrimental affect because you've 'lost' the 25 foot height of the feed point being on top of the house. But then again, you will contend with a difference in polarization between a mostly vertical antenna and a mostly horizontal antenna. That difference in polarization can make more difference than antenna height at times. Just depends on what frequency range and what the transmitted signal is to start with.
Mixed up yet? The 'cure' worse than the 'bite'? Who says you can't try it both ways to see which works best for you?
- 'Doc
(Do the easiest one first, then the hard one. That way you only have to do the hard one once.)
(There's no need to enclose that ground wire in PVC. Just use insulated wire.)
One alternative is to put the feed point at the service ground, and then string the thing as hig as you can get it. That would certainly keep the length of the ground wire short. But, it will also have a detrimental affect because you've 'lost' the 25 foot height of the feed point being on top of the house. But then again, you will contend with a difference in polarization between a mostly vertical antenna and a mostly horizontal antenna. That difference in polarization can make more difference than antenna height at times. Just depends on what frequency range and what the transmitted signal is to start with.
Mixed up yet? The 'cure' worse than the 'bite'? Who says you can't try it both ways to see which works best for you?
- 'Doc
(Do the easiest one first, then the hard one. That way you only have to do the hard one once.)
(There's no need to enclose that ground wire in PVC. Just use insulated wire.)
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A couple of points:
1. Get the antenna element as far away from the house as possible (to avoid RFI)
2. Height of the antenna element is also important but see #1 first
3. As LtDoc said, try it without a ground first. A long ground wire is definitely not recommended.
4. You could put the balun at the 2ft level next the house and then run a long antenna element in a L shape (up to the roof and out, away from the house)
5. Using the service ground is fine -- just keep the ground lead short (i.e. less than 3ft) --- use a thick gauge wire.
6. Experiment!
1. Get the antenna element as far away from the house as possible (to avoid RFI)
2. Height of the antenna element is also important but see #1 first
3. As LtDoc said, try it without a ground first. A long ground wire is definitely not recommended.
4. You could put the balun at the 2ft level next the house and then run a long antenna element in a L shape (up to the roof and out, away from the house)
5. Using the service ground is fine -- just keep the ground lead short (i.e. less than 3ft) --- use a thick gauge wire.
6. Experiment!
ka3jjz
Wiki Admin Emeritus
The PAR is not a longwire - boy do I wish we could purge that term! - it's essentially an end fed L, with a transformer...for those that have never heard of this antenna, you might find the following enlightening...
Par EndFedz Antennas - LnR Precision Inc
True longwires are a totally different animal, and most wish they had the room to put a few of them up (I know I don't!)
best regards..Mike
Par EndFedz Antennas - LnR Precision Inc
True longwires are a totally different animal, and most wish they had the room to put a few of them up (I know I don't!)
best regards..Mike
Very true Mike. Longwire = minimum of 1 wavelength.
OK, not sure if I have longwire yet. I replaced the 45 foot run with about 400 feet 0f 14 gauge wire strectched into a vee from my house to my garage to a out building on the property. It woke my R75 up. Now the next question, I am running through the bauln of the enn fed, should I run the wire direct to the reciever? If so were should I hooh the ground wire at the reciever?
Hell no. I presume you mean you're using coax from the transformer to receiver..? What coax did you get and how long is that line?
It sounds like you're done from what I can tell. What else are you expecting?
Nickcarr makes it sound like I am done. Maybe I am on the antenna end, but now it is time to change to another forum topic and help me firure out this Icom R75. I used to think I understood and was good at RF until this arrived at my door! I need to play with it for a few more days, then all you guys get ready for some questions.Thanks again for all the help.
I would have stuck with RG8 or better coax (50ohms) but the RG6 is okay. You got the quad shield which is pretty good stuff. For only 20ft, the radio won't know a difference.
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