Tennadyne T-11 on the way! any advice on using with the 6500?

Walt - KZ1F

Assuming, for the moment the M2 17-30LP7 is really the Tennadyne T7, one issue I faced when assuming the holes were mis-drilled is I had the piece backwards. One thing the folks at M2 told me is that all the drilling was computer controlled. Consequently, none of the holes were misdrilled. Double check, I found it an incredibly easy mistake to make especially when I started getting tired and all the aluminium started looking identical.

Walt - KZ1F

I don't know that the gain will be any different than on the T-7 but you will have 20M. I say that only by way of agreeing with Charles, Ken, it will **** your mind. For an LP, it is an OUTSTANDING antenna. Then there is the whole benefit of, it turns too.

Ken - NM9P

I found that to be true a few times regarding the boom-to-element mounting holes. On some of them the bolt wouldn't go through until I twisted the element 180 degrees. There was a slight variance in the angle of the **** holes. In the snag I found, the boom spacer is a pair of plates with four holes drilled in a square - two holes for each of the two booms. I couldn't seem to match the holes up on the boom no matter how I adjusted the plates. The holes in the booms seemed to be just a little too far apart...almost there, but not quite. I couldn't get both screws in the holes at the same time. But it was getting dark and hard to see, so I quit for the night. I will hit it again later this morning when the light is better.

Ken - NM9P

I already have a Yaesu G800DXA rotor. I will obtain a computer interface for it later.

Ken - NM9P

Charles, That is what I keep hearing. Even though I will only have the T-11 up at 38 ft. (The original plan was fo 38 ft. But we scrapped the home built Hazer in favor of simplicity.) Walt, the gain is said to be 5.8 dBd, which is a little bit better than the T-6 or 7, but not earth shattering. But it is consistent across 20-6 meters.

Ken - NM9P

I looked at it again, and no matter how I arrange the plates the boom holes are about one-half a hole diameter too far apart. I can start the screws, but the hole misalignment makes them go in crooked and the plate cannot move up flush with the boom, and the screws won't come out the other side.

I am sending an email to Roger at Tennadyne, but I may just need to drill the holes in the little plate to the next larger size to give me a little more room for them to match. Seems better and easier than wallowing out the holes in the boom. On another front, the guys came to cut down the tree in the front yard this morning, so no shade to work under! ( the tree had been hit by lightning a couple of times and showed signs that it was beginning to die. The church trustees decided several months ago to remove it before it became a hazard to the house or people. But the timing was unfortunate!)

Walt - KZ1F

That is a tad unnerving. Maybe M2 does do their own 7 ele LP and 11 and 12 ele lps.
I just checked on their instructions for the 11 ele one, it has a round boom, yours looks to be square. But if things are not machined correctly that is not good. I am sure you don't want to wait till Monday but before you start drilling, you could check with them.

Ken - NM9P

Yes, it is a parallel, square boom. It is engineered very well, as far as I have seen, except for the spacer plate. Otherwise it seems to be real solid. Only the initial stubs for each element are non standard lengths. After that, each element or element section is either 2, 3, 4 or 6 feet in length. The element build-out won't take long once I get the booms finished. The boom to mast plate seems to be really solid, and the "slip-Nott" looks like it will be very helpful.

KY6LA_Howard

As an old antenna builder I would second Walts comments. Invariably when holes do noyt align we either had them upside down, 180 degrees rotated or were using the WRONG part.

Ken - NM9P

The Hazer idea was scrapped, and I don't think he wants to build any more. It was going to be too expensive and too much hassle. I will pass you info on to him if he is interested.

AE0MW

Allright, thanks for the followup Ken!

Good luck with the T-11, my friend has a T-10 and absolutely loves it. Once I can find a solution for my HF tower issue it's going to be a tough choice of antenna for me.

-Mike

Ken - NM9P

Update 6/7/2015 I got the boom halves mated to one another and the boom to mast plate installed. Everything except the four bolt boom spacer fit perfectly. I have posted pics of Friday night's work and this afternoon's work. All that is needed is to fix the last boom spacer plate issue, tighten all the spacers, and then build out the elements. The element build-out won't take all that long, they are all standard lengths...Plug & chug! as we used to say in Physics/Calculus classes in college. Booms ready to invert and assemble. Aluminum foil plumbing tape sealing the holes in the boom. I hope it doesn't come loose and short the boom sections! Booms inverted and ready to start attaching the spacers. The double boom serves as a transmission line. The element halves are attached to opposite booms, giving the phase shift for the log periodic feed. No need for cross-crossed feeder wires. The boom all assembled (except for the one spacer plate issue). The infamous spacer plate! You can see the mis-matched holes. No matter how I rotate it or flip it, none of the holes match up. The holes on the two plates are a perfect square and the screws always match each other. But the holes in the boom are half a hole diameter too wide. It is the only spacer with four holes. All the others are singles and had no problem. I am waiting for contact from Tennadyne. Hopefully I can resolve this and build out the elements on Monday. Ken - NM9P

Steve K9ZW

What is the foil tape for?

All things given, if everything else measured correctly I'd adjust the plates (I'd leave the boom as is iff possible, even though they are a softer easier to work metal). 

73

Steve
K9ZW

Ken - NM9P

The tape is to seal all of the holes in the boom sections to keep insects out. The element stubs mount through the boom, and have a **** that goes through a large hole in one side of the boom, seats on the element, and goes through the other side of the boom and is tightened with a Nylock nut. Solid construction, but the holes need sealed after the antenna is assembled to prevent insects, and hopefully seal against water buildup. I will also be plugging the boom side of the elements to prevent "**** piping" whenever the wind blows. The ends of elements will get foam rubber ear plugs to keep out insects and prevent **** piping.

Steve K9ZW

If an issue, I would have selected a non-conductive UV stable caulk sealant, as not all Aluminum Tape is created equal.

Scotch Brand (typically #3311) usually dies outside, but if you used 3M's 438 or 425 Aluminum Tapes you have a good chance of having it perform for many seasons.

Again I'd gone non-conductive caulk, perhaps something like Sikaflex 291.

I left mine open and no issues here, but then it is Wisconsin.

73

Steve
K9ZW

Ken - NM9P

Yeah, I hope this wasn't a mistake. I originally had the idea of using aluminum tape on the element stub ends at the boom. I wanted it to blend in. Then I saw how smooth the inside faces of the boom would be with the aluminum foil tape and decide to use it. I cleaned the surfaces with alcohol sterlizing pads ( I have lots of them for my blood sugar testing) then dried them with paper towel. After applying the tape, I rubbed it down with a socket in order to get all the air pockets out and stick it down well.

The instructions called for "good quality electrical tape." I hope it sticks.

Ken - NM9P

Ken - NM9P

Update - June 17 On Monday I almost finished the antenna. Finished built out of elements, except for one 6 ft. tip that would have hit my son's swing set/playhouse. Will put that on after turning the antenna. Antenna pieces took a little longer because I needed to polish the ends of the elements to remove a little oxidation from sitting around waiting for assembly. BTW..Scotchbrite green pads work wonders! I coated the ends of all pieces that telescoped into larger pieces with about 3 or 4 inch coating of Penetrox. Covered all the screws, too. Need to re drill the spacer plates and install them, align spacing and tighten all the spacers, install shorting stub at rear, coax feed/Collins choke, and plug all the element ends. Then I am ready to go up. Unfortunately the weather and my work schedule have not cooperated. I also will be making a trip out of town for a while, so this monstrosity might have to sit on sawhorses for a week or two before it goes up. There is always something! I have waited this long. A little longer won't **** me! Sorry for bad pictures. The leather case on my iPad slipped and partially covered the lens. Ken - NM9P

Ross - K9COX

Curious what you found out about the hole alignment issue?

Ken - NM9P

He was going  to send me new plates, but they haven't arrived, yet.  i will probably just file two of the holes a little longer and use what I have.  Their main function is to keep the two booms at an even spacing.

Ken - NM9P

Update June 18: Got the A148-20t 2 meter antenna finished today. 10 elements vertical, 10 elements horizontal. This will go on top of the T11 at about 45 ft. The T-11 will be at about 38 ft. Thanks to Jerry, KC9ZAR, for building the top plate for the tower and installing the rotor and **** bearing. Couldn't get much finished on the T-11 due to weather and work. Taking the day off tomorrow to see if I can get it finished. Slow, but making progress. And I am encouraged. Hope the weather cooperates. Ken -NM9P Can't get a very good picture of it inside the garage.

Paul Christensen, W9AC

Ken,

Joining the discussion a bit late as I've been traveling through EU for the last two weeks...

Before mounting the T-11, make absolutely sure you measure the length of each element from the boom to the tip of each element.  Regardless of how close it looks, confirm the data with Roger at Tennadyne.  Do not assume each element is the correct length just because it looks right. 

On my T-14HD, the total element lengths were missing on the supplied documentation.  Yes, each element segment length is described in great detail but what's needed is a final validation to a fraction of an inch of each element length.  On my T-14HD, some element tubing segments are within a half-inch of each other and can easily be mixed up during construction.  

After construction, you can lift one end of the rear shorting bar.  Measure DC resistance between the two booms.  It's should read open with a DVM or VOM.  Reconnect the shorting bar.  In our T-14 instructions, the step to install the shorting bar was completely missing. 

The T-14HD went together with no re-drilling needed.  I was very much impressed with the mating accuracy between segments.  There was no slop whatsoever.  Noalox was used as an anti-seize compound.

Arguably, the Collins choke should be augmented with a second RF choke at the BMI connection to better isolate common mode current.  See W8JI's assessment; he describes this in detail.  We have not added the second choke but may try it when the WX cools in the fall.

http://www.w8ji.com/baluns_on_log_perodic_antennas.htm

Finally, when mounted at the top of the tower, try and immediately conduct a sweep of the T-11 with a CIA or VNA device -- especially while the tower and ground crew is still there.  Try and avoid simple SWR devices as they do not present the complete story. 

The sweep will show periodic changes in SWR, possibly along with some surprises like the attached image below.  What's shown is a complex Z and SWR sweep of my T-14HD from 30m through 10m.  The shaded gray bars show the amateur bands.  Note the extremely sharp SWR spike just above 17m.  I have several theories based on input from Roger, W8IO and L.B. Cebik's material.  W8IO is a commercial LPDA designer.  In actual practice, it's not a concern and is not affecting gain nor F/B performance. 

 

Ken - NM9P

Update June 18 Finally got everything done on the T-11. Spacer plates drilled out and installed. All boom spacers realigned and tightened. boom to mast plate reinstalled and tightened. Element ends and stubs plugged or taped. Collins choke/feed line installed. Rear shorting stub installed. Had to run to Fastenall to get another bolt because I twisted one off on the spacer install. Only broke two small bolts, and lost two nuts and one 1/4 inch socket in the grass. Not too bad for this complex assembly! Rain threatened all day. Looks like it will finally get here. Ken - NM9P

Walt - KZ1F

That is exciting Ken, so remind us, what is it replacing and how high is it going? If it is replacing a dipole at 15', you are in for a treat.

Ken - NM9P

It is going up at 38 ft. with the two meter antenna 7 ft. above it.

My current antennas are:
1) a 160 Meter offset fed dipole with the feed point at 38 ft. and the ends drooping to various heights...short leg at 18 ft. long leg makes two bends and varies ...8 ft. 24 ft. And 18 ft on the corners. 2) a 33 ft. elevated vertical with four sets of elevated radials at 8 ft.
3) a 6 Meter squalo on top of the hoist at about 25 ft.

Yes, this will be a great improvement. I wish it was going to be higher, but will be very functional.

Ken - NM9P

Bill N5TU

You should see a huge difference!  Now, it's time to get my towers in place and my SteppIR installed!  :-)

Ken - NM9P

I have a tower! Who Hoo! The T11 is up at 38 ft. It is connected "temporarily" in the shack until I finish routing cables more permanently, etc. on paths to Europe and the Middle East on 17/20 it seems to average about 2 S-units above my dipole and verticals. I haven't had path openings to other directions yet. But here were several stations in Oman and U.A.E. that were Q5 copy that were unreadable on the other antennas! This is going to be fun.... Thank you everyone for your encouragement and support! Ken - NM9P

Walt - KZ1F

That's so cool Ken! What is the tower?

Ken - NM9P

35 ft. of Rohn 45G, self supporting with 5x5x5.5 ft of concrete at the base.

Ken - NM9P

Here is my SWR plot...not bad, except for 12 meters.  The boom resonance SWR spike is too close to the band.  I need to shorten the shorting stub on the rear.  There was not a good way to test this on the ground, (they say it always changes when you get it up in the air.)

Since we used a crane and climber instead of a bucket truck, I couldn't test it in the air and have them adjust it.  Perhaps I can get a man lift cheap and adjust it later.  Right now I am enjoying playing with it...at least I will when the thunderstorms pass through!  ugh!.

Ken - NM9P

Bill -VA3WTB

interesting way to put up a tower ken, on it's side?