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PDL-II antenna has 2 feedlines.

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Old 06-11-2013, 07:55 PM
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Default PDL-II antenna has 2 feedlines.


I want to make a "poor mans Balun" at the feed point. Should I coil the feeds together or make separate coils?


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Old 06-12-2013, 12:19 AM
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Quote:
Originally Posted by commando57 View Post
I want to make a "poor mans Balun" at the feed point. Should I coil the feeds together or make separate coils?
I am not an expert but 1 will be around soon .....
May ask what you are trying to achieve ?? if we know some one may have a different solution..
Also is your PDLii on the ground? if it is i would love some photos and measurements of the matching network as i fancy a homebrew 3 element pdl2
Thanks dave

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Old 06-12-2013, 12:30 AM
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Quote:
Originally Posted by commando57 View Post
I want to make a "poor mans Balun" at the feed point. Should I coil the feeds together or make separate coils?
Doesn't take an expert to figure this out.

You don't need it. An 'ugly balun' as they are called - isn't needed for a PDL-II. On an Imax, A99, or some other vertical antenna - it may well be needed. "Don't try to fix something if it ain't broke". The PDL-II is a fine antenna and a balun won't do a thing. Waste of time. A balun is used to stop a problem called 'common mode current' that is a typical problem with vertical antennas.

If you thought you would get more performance out of it; then you were wrong.

Are you having a problem with your PDL-II?
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Last edited by Robb; 06-12-2013 at 12:45 AM.

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Old 06-12-2013, 05:38 AM
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I've had a few PDL II antennas and have a different point of view on this. The coax choke or balun is not just useful on end fed verticals. It can also be a benefit on many beam antennas. Common mode currents can be a problem when feeding a balanced element with a gamma. While the gamma takes care of most of the issues going from an unbalanced coax to a balanced driven element, there are often some noticeable currents that can cause the coax to radiate.

With the PDL's I've used, I make a pair of separate chokes or use ferrite beads on the coax at the antenna. You want to separate your chokes if you use coiled coax. If you form both coax chokes together, the one in use can induce unwanted currents into the other coil and cause that coax to radiate.

In all but the most severe cases, we are not adding these chokes because we expect to see noticeable improvements in antenna performance. Adding chokes on a PDL-II is usually done to reduce RFI since there should not be CMC levels high enough to cause noticeable distortion in the pattern or significant loss of drive to the antenna due to power radiated on the coax.

Dave, I have a completely rebuilt PDL hanging in my shop. It's mostly assembled and had a perfect SWR when I used it last year. If you need any measurements on the orbital gamma matching system, I can provide that to you. Let me know what you're looking for specifically and I'll take some measurements.
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Old 06-12-2013, 06:36 AM
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I think it won't hurt or overerly help it. I had a PDL up for years, even retuned to 10 meters when I became a ham. It worked great as is and I really had no issues with it. I don't believe the gain figures, it's closer to 9db then the stated 12 but overall an awesome antenna.

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Old 06-12-2013, 08:08 AM
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Default PDL-II

Vertical is perfect 1.1 and 48 ohm. Horizontal is 1.3. Antenna is just up enough for checking vswr. I am getting a lot of noise (3 2950 bars) that I don't have with my Antron. Reflect is 5-6 on vertical and I haven't transmitted horizontal till I adjust. I can hear rf in the house that is not there on the Antron. I haven't grounded anything yet. More to come.

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Old 06-12-2013, 10:15 AM
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The SWR should be tuned with the reflector on the ground and the driven element pointing up at the sky. Tuning it low to the ground and in its normal upright position will cause the SWR to change once its up higher.

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Old 06-16-2013, 01:33 AM
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[QUOTE=.

Dave, I have a completely rebuilt PDL hanging in my shop. It's mostly assembled and had a perfect SWR when I used it last year. If you need any measurements on the orbital gamma matching system, I can provide that to you. Let me know what you're looking for specifically and I'll take some measurements.[/QUOTE]

That will be very good..... i did find a website with a homebrew pdl2 and i was going to post you a link and ask you if their was anything else i needed to know..
But i have just spent the last 2 days looking for it and not find it...
I have found out how it works ish ....i believe by looking at photos 1 loop connect to 1 of spreader arm for one polarity and the other loop connects to another spreader arm for the other ..
What i cannot see from photos on the net is how the loops are fixed to the boom, cannot see if they are insulated from it or not..
What i think will be a VERY good ider is if you started another thread that without doubt needs to be in the sticky list. as info on this antenna is not in abundance on the net
I Think the dimension need to build one are
1 Confirm that the driving element wire is 1 wave length long
2 spacing of elements on boom
3 length of the spreader arms the loops are connected to
4 length of the loops
5 photo of the loops attached to the boom and feed points
6 details/ dimensions of the gammermatch
I dont think i have missed anything out
thanks dave

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