Another vertical antenna attempt, LDG S9V31 this time

Hello,

My previous attempt was with a Comet vertical which was supposed to be used with no radials and to me at least it didn't work out at all. I've posted it on this forum, the majority agreed that one with radials will do better than the Comet or even than GAP Titan DX I was tempted to buy. However at my previous location I had no room for radials.

Now I've moved to a different house, got a 40 by 16 meters garden. I've installed my old good inverted V at about 10 meter height, same quality like before, it's okay for a small radius, can't really get too far. Yagi out of question, time to get a vertical again.

Bought a S9V31 from LDG, plan to use it exclusively on 40 meters, it is cut just about right. Today I've laid 500 meters of 1.5mm stranded coated PVC cable in the garden which made 47 radials and I did not covered everything. Not the best, I have to buy another 200 meters or so to fill the gap. Funny thing, I've paid £65 for antenna and then put £100 in radials, and I still have to buy some.

The antenna is not impressive, looks like a green fishing pole, some couple of pages ordinary paper laser printed instruction manual, anoter small bag with the plastic clips, everything looks cheap (and it is at this price). I've bought the recommended 1 meter 1"3/4 galvanized steel bar which fits perfect with the base of the anetnna.

The first issue is with the wire inside the antenna tube, it ends with a metal ring. So trying to figure out how to connect it to the RG213U cable, there is no instruction of what so ever about this process. Interesting enough, if you search for the manual, on the LDG website you can find the actual and the old manual. While the old one has a section dedicated about how to connect the metal ring to the feeder, the existing manual has nothing about it.

Emailed LDG, got a reply about it some hours later, prety much explaining what I already knew and saying nothing about my question, how do I connect the metal ring to the feeding line. Not the biggest issue anyway, I just thought I may cut the metal ring and have the wire directly soldered to the hot wire of the coax cable or put a metalic ring at the end of the coax and have them together via a bolt, then insulate it somehow.

But then the second issue, reading the printed papers of their manual, there is something which caught my attention

"Balun/Unun

For 40 meter monoband use, a 1:1 choke balun should be inserted in-line with
your coax outside of the radial field to prevent RF from coming back into your
shack over the coax shield. Use the LDG RBA-1:1 for up to 200 watts or a unit
from Balun Designs for more than 200 watts."

Hm, outside of the radial field? This was a bit strange, so I have to run the coax from the antenna thru the ground until I pass the radials covered area, cut the cable, connect the 1:1 balun, make another cable and run it to my shack. Not being sure about it I emailed again LDG explaining my scenario and citing the manual, asking about where to position the balun and got this reply:

"
Hello,

We do not recommend that type of installation. However, you are free to try
any configuration that you like. "

Um, but I am just trying to follow the instructions from the manual, not to invent something new. These guys must be very busy not to have time to give a proper reply to a customer. Not to mention that last email where I was asking about the metal ring was left unanswered.

I would like your input about where to position the 1:1 choke balun and anything else you think it's important, I prety much believe their manuals is useless or does not contain exact information and their technical support is unfortunatelly low quality. Althought the antenna has a 5/5 rating on eham (the reason I bought it) so far I do not feel it really worth the merits; but it's not yet up in the air.

Thanks.

Cornell

 

That wouldn't last through one wind storm here where I live. However in less windy areas it seems a good deal.

I'd drill a hole near the bottom of the lowermost fibreglas tubing and use a long machine screw with two flat washers, a lockwasher and a nut and use that for the antenna wire "ring" and also for the Unun connection, with the other Unun connection to the grounded mounting pipe and radial field. That keeps everything nice and mechanically sound, with good electrical contact.

You don't need to keep the Unun out of the radial field; you want to keep the coax itself out of the radial field if you can. With a ground-mounted vertical and radials, to accomplish this I just run the coax underground so there's several inches of soil between the radials and the coax. Seems to work fine. I'd put the Unun right at the antenna feedpoint.

 

Radials are a good investment: you can put any vertical over them in the future. If I were you I would have just laid 47 radials... I guess you were shooting for a pattern of 64 radials 1/4 wavelength long and ran out of wire? What you have already is probably a quite excellent system even with the missing sector so you can just go ahead and use it for now.

I usually install some kind of connector. For example, this is the feedpoint of my 10 foot tall 40m vertical:

http://n3ox.net/projects/n3oxflex/feedpoint_lg.jpg

I used an SO-239 bolted to an insulating (fiberglass) board which has permanent soldered connections to a pair of bolts, also through the insulating board. I use the bolts to attach the required shunt matching coil and Anderson powerpoles to connect to the antenna, but the same connector-and-bolts setup or something similar could be good for the feedpoint of the S9. I like to use a connector at the end of the coax just because even an unsealed PL-259 is more rain/weatherproof than an open end and it's nice to be able to easily detach the coax without too much hassle... good if you need to use an analyzer at the base of the antenna or whatever.

You have so many radials that it's very unlikely you need any kind of feedline choke. They're important for elevated systems and for systems with just a few radials or really short ones but you've established such a good RF ground at the antenna that there's going to be very little current flowing on the coax.

Steve's suggestion to bury the coax below the radials is good. I would have to do some work to figure out if I thought it was good to put a choke at the edge of the field or not but I doubt you will have any noticeable effects with any choking configuration, buried, not buried, whatever. Burying has the advantage of neatening up the installation... grass will pull the radials down and make them vanish but the coax probably won't, at least not for a long time. I have some pretty aggressive weedy plants in my backyard that might do it but I wouldn't rely on it

73,
Dan

 

Cornell,

It does sound like you were cutting the radials to be 1/4 wl, but that is not really necessary as the ground (I assume they are buried) is going to detune them anyway, but in any case you have a great ground system there. I've looked at that antenna as well, but never quite made the commitment to buy one when I could just buy aluminum tubes at the hardware store for far less. I'm lucky in that I have a completely grounded metal roof, so no need for radials at all and I have 3 different verticals up there that work FB. They are all fed with one line and there is a single ferrite bead balun at the base. No discernible problems with RF or performance.

Let us know how you think the S9V31 works out in the end.

 

do you have trees to use as supports for an inverted L ? Very low profile. Can be modified to work 160 to 10 meters.

 

I have the same antenna - which is a S9 31 foot vertical. I had mine attached to the roof at 12 meters with 8 radials - 4 for 40 meters and 4 for 20 meters. The wire from the vertical came out a hole on the side about 200 cm from the bottom and here is where I attached a 4:1 balun (since I wanted to work multiple bands). The balun was then connected to 50 feet of RG-213. Everything worked rather well..

73s HK2LS

 

A balun is not needed.

 

If it were me I if it need one I would use one inside the tuner and hope for the best on RF but I don't think one will be necessary with the coax buried. I don't with mine and I run 1K on 10-160m with no RF with a Hy Gain Hy Tower 64 radials stapled to ground coax buried just 3" below ground.

 

Thanks everyone for the advices, I finally got it up and running last night. Installed 60 radials, total of 600 meters of 1.5mm green yellow flex stranded cable. Here some pictures of the current installation.





At that time CQ WPX contest was still on so I managed about 50 contact in 1 hour and half, just to test the antenna. Band was crowded with the contest, I had to repeat myself several times to get the other station copy my call, but I was expecting that. Not the best time to ask for a A/B antenna comparison.

I have a FT1000Mp MkV, switching between the inverted V and the new vertical at night time, seems like the vertical was a bit louder, but not by 1s unit, just a bit louder. I've tried again today at daylight time, the vertical was very noisy, as expected, while the inverted V was beautifully quiet. At daytime 40m was not good, just some local stations.

It's way too soon to make any comment on performance, I'll resume at the building quality and installation notes. I am using the required pole support, however, it swings in a very low air current, I believe it will crash at a medium wind blow. I couldn't make those tube rings stay in place, put them once, erect the anetnna, have the second section collapsed alsmost crusing the internal wire. Very poor design, I had to take it down, use electrical tape on all joints to finally make it stay one piece. I'm planning to try again during the next weekend to seal those rings in place, I'm wondering if anyone managed to do it properly and secure tube sections.

Since they do not provide any instructions about how to connect the wire to the feeder I took a Palstar to SO239 open wire fitting from an old G5RV and use it with the vertical antenna. Connected very nice to the RG213U cable. Since it was running late I didn't have time to bury the 50 meters of cable so I had it on the ground. I don't have yet any balun installed yet no RF symptoms in the shack were noticed.

SWR on the low portion of the 40m band was under 1.5, and about 1.5 on the upper side. Both with internal ATU on. I've ordered today the AA-54 antenna analyzer made by Rigexperts, should be with me tomorrow, once I have it I'll deploy some graphs and figures of both vertical and my good inverted V. Also during this week I'll try to do lots of A/B comparison, if anyone wants to help please let me know which time is best for you and I'll try to meet you on 40m.

If you spot any errors or have comments, please share your opinion.

Thanks.

 

Looks like the house is in the way. I'd knock it down.

Seriously, looks pretty nice. I wouldn't trust it in strong winds, either.

We don't get them often but every now and then have 60-70 mph gusts and they separate the men from the boys when it comes to antennas. The "locals" using the S9 31' models have all lost them when that happens.