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has anybody tried a "Balun Kit"
- Thread starter GnG8d
- Start date
If it is a two elemant quad the 1:1 wont work unless you are going to use a matching transformer also,
Impedance of a two elemant quad is around 100 so will need a 2:1 balun to match it to your transmission line.
Balun is a balun by time you wrap it weatherproof it and install it may be less expensive to just purchase one.
2:1 baluns can be custom ordered. Check out this site.
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You can always feed the quad with a gamma match to provide a 50 ohm impedance.
First, it isn't a balun at all, it's a choke made using ferrite instead of coils of coax. Second, there is no such thing as a "one size fit's all" ferrite choke usable from 160 to 2 meters. That's especially true for absolutely any mix of ferrite if only 9 inches of coax is required to hold all the ferrite cores required for effective 'choking' at any frequency between 160 and 2 meters.
Strictly speaking, Palomar isn't lying in their ad, but they are definitely NOT telling the whole truth about using ferrite cores for 'choking' off CMCs. There's been more than one study of this sort of thing done. All of them show that there are varying degrees of attenuation depending on the size, type, and the number of 'passes' of a conductor through a ferrite core. While ferrite will attenuate CMCs, there are other methods that can be more effective for given situations. (A bicycle can certainly be an effective way of getting around, but makes a terrible way to move a loaded semi trailer! About the same difference here. That's an exaggeration, but not a very big one.)
- 'Doc
Strictly speaking, Palomar isn't lying in their ad, but they are definitely NOT telling the whole truth about using ferrite cores for 'choking' off CMCs. There's been more than one study of this sort of thing done. All of them show that there are varying degrees of attenuation depending on the size, type, and the number of 'passes' of a conductor through a ferrite core. While ferrite will attenuate CMCs, there are other methods that can be more effective for given situations. (A bicycle can certainly be an effective way of getting around, but makes a terrible way to move a loaded semi trailer! About the same difference here. That's an exaggeration, but not a very big one.)
- 'Doc
Since this topic was being discussed, I thought I might ask a question of my own. When the PDL II quad came out I purchased one and ran it with an 8877 amplifier. I also had a groundplane. I remember the PDL II worked great for it's size but totally sucked in the area of RFI. The groundplane had less signal but could take more power with less RFI. The coax was top quality quad shield mil spec Ethernet cable. Now I learn about CMC, coax / mast radiation and wonder how much of the RFI from the PDL II was related to this and could be avoided?
I finally purchased another NOS PDL II for $250 and am anxious to install it. Having avoided RFI problems with the same amp in my new location to this point, I'm wondering what the best way to prevent it with the PDL II is going to be. At first I wanted to use air wound chokes for power handling at the feedpoint but realized this would place the "inductors" directly inside the circumference of the driven loop. Possibly inducing more RF onto the coax.
Then I figured it might me better to not use coils there and go with a large number of ferrite cores at the feedpoints. In this case the coax still has to pass right through the back side of the radiation plane on the driven element. I wondered if it might be a good idea to choke the coax off in two locations? Right at the feedpoint and again 1/4 wave down the coax and outside of the radiation loop. How about insulating the mast above the rotor to provide isolation here too? Anyone feel this is beneficial? My mast would only be about 10 feet but that's over 1/4 wave.
Thanks for any input on this one. I really liked the performance of this antenna back in the day. The dipole driven full wave quad element with switchable polarity was revolutionary in the design of the quad. It produces virtually the same gain as my 3 element yagi did with less then half of the turning radius. I think the rejection was better too. Especially if you wanted to null out an undesired signal. The reflector element being able to block signals in all radiation planes seems to have benefits over the Yagi reflector.
One added note, you can also correct the match to a standard two element quad with a simple 75 ohm "Q" section of coax at the feedpoint. Just make sure the 75 ohm coax is cut to the electrical 1/4 wavelength with the velocity factor calculated in. This works good on a single element quad too. I use one on 75 meters and it beat my old dipole and vertical.
I finally purchased another NOS PDL II for $250 and am anxious to install it. Having avoided RFI problems with the same amp in my new location to this point, I'm wondering what the best way to prevent it with the PDL II is going to be. At first I wanted to use air wound chokes for power handling at the feedpoint but realized this would place the "inductors" directly inside the circumference of the driven loop. Possibly inducing more RF onto the coax.
Then I figured it might me better to not use coils there and go with a large number of ferrite cores at the feedpoints. In this case the coax still has to pass right through the back side of the radiation plane on the driven element. I wondered if it might be a good idea to choke the coax off in two locations? Right at the feedpoint and again 1/4 wave down the coax and outside of the radiation loop. How about insulating the mast above the rotor to provide isolation here too? Anyone feel this is beneficial? My mast would only be about 10 feet but that's over 1/4 wave.
Thanks for any input on this one. I really liked the performance of this antenna back in the day. The dipole driven full wave quad element with switchable polarity was revolutionary in the design of the quad. It produces virtually the same gain as my 3 element yagi did with less then half of the turning radius. I think the rejection was better too. Especially if you wanted to null out an undesired signal. The reflector element being able to block signals in all radiation planes seems to have benefits over the Yagi reflector.
One added note, you can also correct the match to a standard two element quad with a simple 75 ohm "Q" section of coax at the feedpoint. Just make sure the 75 ohm coax is cut to the electrical 1/4 wavelength with the velocity factor calculated in. This works good on a single element quad too. I use one on 75 meters and it beat my old dipole and vertical.
359, waverider raises a good point. I'm not too sure he is right about using a gamma as he describes however.
If you describe what your antenna is, it would help these guys to know what to say. A two element quad needs matching, but as I understand a 4 element can be constructed to allow for direct feed, so a description is just good information for everyone to have.
Shockwave, I haven't considered the actions of a PDL in a while, but maybe I can give you some words shortly. Right off the bat, the PDL does not work exactly like a traditional quad element regarding the matching or the radiating parts. As far as I know, it also is not known to show problems with TVI, so I would think it possible your bad experience could have been a bad insulator, or some other construction problem that was not so obvious. That thing has a lots of parts where a bad RF connection could exists. Maybe such a connection was good enough for continuity, but just poor enough to create TVI.
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359, I wrote a list of things to consider, but I noticed your new concern about answering questions about your matching network. So, I'll hold my advise and hope to satisfy you as to why the matching information might be important.
Such information from you might be important to considering the potential for the problem you are worrying needlessly about. There is a simple way to test this problem. However, without good input from you---these guys can't give you good advise. So, don't let questions get you all upset.
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Nobody is upset, I can assure you. I planned on using the 75ohm matching cable instead of the matching transformer which limits power handling and bandwidth. If that's not optimum, I have no problem listening.
I started this because I have an open air choke that I made for my M103, but for now I'd like some input on these "sleeve baluns" or "sleeve chokes" or whatever you want to call them. I had the wound choke mounted on the boom, directly feeding the gamma on my M103, but I don't see a decent way to mount it on the quad. It could be placed between the matching cable and feedline, but a 1/4 wave won't get it down the mast, hence my curiosity in these "kits" from Palomar-Engineers. This would make a very clean install, IF they work.
I understand about the coaxial choke hanging out there near the tip of a fiberglass spreader arm. That's not a good thing. But, I don't understand your distinction between the 75 ohm matching cable and the matching transformer.
Part of my words I haven't posted yet were asking you to describe, in detail, what the matching part of your antenna looks like, and maybe even some pictures since it's on the ground. But after going back to the thread for a reference, I saw your words discouraging us from asking about the matching section, so I took them down from my "Posting Que."
We can talk about sleeve baluns/chokes, but I can't see how that would apply unless we make some assumptions about the matching device that Signal Engineering uses for their dual polarity White Lightning Quad maybe.
Can you give us some close up pictures of the parts you note above? That may be helpful to describe better what the 75 ohm matching cable and the matching transformer is in your mind.
The simple way to check your antenna for TVI. If you're in the open with nothing really big and destructive close to the antenna, set it up 10' or 20' above the Earth and test it. You have to construct it somewhere, so use that space to test for TVI too. Then you'll get an idea whether to worry or not.
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A four element quad should present an decent match for 50 ohm coax.
So if Indeed you are going to use a four element quad you do not need a matching device. direct feed it, use an ugly balun at the bottom of the mast and enjoy,
Unadilla or any other good balun supplier has all different assorted types of feed, even one that will work on your quad, same as a dipole, coax connector on one end two wires coming out at the other, use 1:1 current type to force equal amounts of current in each leg and watch those wires come to life.
Keep in mind it is rated at 1.5KW SSB not CW or AM, so if you intend to use excessive power ( do not ask me to define excessive power) you will need a balun that will fit the need.
Google is your best solution for this, google quad antenna you will get 10000000 of hits, read and see which is best for your installation.
TVI??? One word, ground that tower, not with one ground but in accordance with the hand book, three ground rods spaced accordingly, use a choke,balun or whatever to stop CMC and you will not see any TVI/RFI.
Of course the old adage, the amplifier only amplifies what you put into it, if it is dirty going in, it is dirty coming out.
A 75 ohm matching cable/phasing harness etc etc is sometimes referred to as a matching transformer, either way it is 1/4 wl times velocity factor, but in phased arrays use 3/4 wl as 1/4 wl with velocity factor figured in wont reach the antennas if spaced 1/4 wl apart.
So if Indeed you are going to use a four element quad you do not need a matching device. direct feed it, use an ugly balun at the bottom of the mast and enjoy,
Unadilla or any other good balun supplier has all different assorted types of feed, even one that will work on your quad, same as a dipole, coax connector on one end two wires coming out at the other, use 1:1 current type to force equal amounts of current in each leg and watch those wires come to life.
Keep in mind it is rated at 1.5KW SSB not CW or AM, so if you intend to use excessive power ( do not ask me to define excessive power) you will need a balun that will fit the need.
Google is your best solution for this, google quad antenna you will get 10000000 of hits, read and see which is best for your installation.
TVI??? One word, ground that tower, not with one ground but in accordance with the hand book, three ground rods spaced accordingly, use a choke,balun or whatever to stop CMC and you will not see any TVI/RFI.
Of course the old adage, the amplifier only amplifies what you put into it, if it is dirty going in, it is dirty coming out.
A 75 ohm matching cable/phasing harness etc etc is sometimes referred to as a matching transformer, either way it is 1/4 wl times velocity factor, but in phased arrays use 3/4 wl as 1/4 wl with velocity factor figured in wont reach the antennas if spaced 1/4 wl apart.
Thanks WR, I've just got a few PIECES stuffed in the attic of my home, but I can't limit myself to 1.5kw ......... well, I could, but I might come across a nice 11m tuber too
It sounds like Marconi doesn't think I'll need to worry about TVI, and maybe I won't. But if I do, are these sleeve baluns worth the effort?
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