Tennadyne Antennas

[WA1GFZ]

Joe,
I was wondering there was no update on FB, Bummer. I replaced a section of roof when I yanked out the skylight and decided pushing 60  and 1 disc operation is not a good age for roofing.
When you get ready to work on it let me know.
I used a pro welder to do my boom. He tacked each sleeve in 4 places rather than a full bead around each joint. He said a full bead will crack. This guy builds race car chassis so took his word. Mine has been up since '97.
I replaced all the plastic spacers with 1/4 inch exterior grade fiberglass. I sent you the pictures of my mods but I think you can get by without all the plates I added since your boom is heavier. I contacted Roger once and came away with the same opinion. I used the stock PVC plate at the center but bolted it to a 3/8 aluminum plate that holds the back stay and mounts to the mast with 4 clamps. I also have a 1/2 bolt through the plate and mast so I can swing it vertical  for service. Also locks it from twisting.

[Steve - WB3HUZ]

That radio stuff will ruin your life!

Get well soon.

Hey Frank,

Yes got a great deal on  a T-10, new in the box for half the new price and it was the latest version with the heavier boom and choke support. I wanted to buy Extra clam shells and make up a larger center insulator for better support and add an overhead truss. I called that guy Roger, got ahold of him once, told him what I needed, said he would get right back to me and never did. Sent a number of e-mails to him along with countless phone calls, he told me when I did talk to him, that he never got any e-mails or phone calls from me.......he's got to be kinding !!!! That guy is a real flake and if I didn't get this antenna new for half the price......I would never order one from him or recommend that anyone else order from him.

Anyway, won't be doing any antenna work for a while, when I was roofing the rear shop, I trpped with a bundle of shingle on my shoulder going down slope and went off the egde of the roof, landed on my side and broke my hand. I'll be in a cast for 4 to 6 weeks.......Can't beleive it.......

[K1JJ]

"I trpped with a bundle of shingle on my shoulder going down slope and went off the egde of the roof, landed on my side and broke my hand. I'll be in a cast for 4 to 6 weeks.......Can't beleive it......."


Oh no, Joe!   Watch out for that HuzMan - he's trouble maker and it's all his fault...

Yep, it's amazing how careful we all are climbing towers but screw up badly when on ladders and stairs. That must have really POed you off when you got up and relaized it was time to take a trip to ER.  Was that a little like the time you dropped the Harley in front of the nurses? 

Since misery likes company, about two months ago I was on a ladder leaned up against a tree. The tree is round and the ladder is flat and of course the ladder swung around the tree and I hit the ground sideways on one leg. I came real close to a broken ankle. It swelled up and I couldn't walk on it for a week. It still hurts a little but is about 85% healed. I've never broken a bone in my life and feel quite lucky I sidestepped this one.

#2: My class E rig blew up the other day. Took me a good 8 hours of troubleshooting and replacing parts to get it going again... sigh

Hope you heal fast there, OM.

BTW, the heck wid that Log guy. You can do a better job reinforcing it yourself anyway.

T

[WA1GFZ]

Joe, BTW if you think Roger was a flake you should have had the pleasure of dealing with the first owner. What an AH insulting SOB.
The last time I talked to him I thanked him for the $750 box of scrap aluminum. Too bad because it is such a great electrical design. Then I built it right. By the time I was done I was kicking myself for buying the antenna when I could have homebrewed something much better.

[Opcom]

Hey Frank,

Yes got a great deal on  a T-10, new in the box for half the new price and it was the latest version with the heavier boom and choke support. I wanted to buy Extra clam shells and make up a larger center insulator for better support and add an overhead truss. I called that guy Roger, got ahold of him once, told him what I needed, said he would get right back to me and never did. Sent a number of e-mails to him along with countless phone calls, he told me when I did talk to him, that he never got any e-mails or phone calls from me.......he's got to be kinding !!!! That guy is a real flake and if I didn't get this antenna new for half the price......I would never order one from him or recommend that anyone else order from him.

Anyway, won't be doing any antenna work for a while, when I was roofing the rear shop, I trpped with a bundle of shingle on my shoulder going down slope and went off the egde of the roof, landed on my side and broke my hand. I'll be in a cast for 4 to 6 weeks.......Can't beleive it.......

- after all the frustration with the company, and falling off the roof - that sucks. Glad it wasn't worse though!

[Tom WA3KLR]

Joe,

Consider yourself damn lucky.  A former colleague of mine was building his home and fell off the roof while doing the sheeting and since then is crippled for life.

Take care,

[N4LTA]

I have a brand new T8 in the box - never opened. I plan to get it up in th enext few months, I hop ethat I have no problems considering the above comments.

[WA1GFZ]

As a minimum don't use the sheet metal screws at each element joint. Drill through and use SS hardware. Nylock nout or better yet find some Aircraft SS lock nuts. #4, #6, #8,#10 depending on diameter. I wouldn't let my kids play under the stock antenna
Second. Have each element end tack welded into the boom. Stock each element half is held in with a 10-24 screw.
Usual failure mode is the longest element rips out of the boom during a storm.
Hope you got the 1/8 inch thick wall booms

[K1JJ]

Frank, was it your experience - when the previous/first owner said the antennas are good for 5-7 years, the normal ham antenna lifetime, so don't worry about the poor construction? (Or something like that... )


T

[WA1GFZ]

Yea, It was something like that. Hams change antennas all the time.
I told the bozo my quad was up for 19 years and wnated to add the new bansd so went LPDA. Then I thanked him for the box of scrap metal.
Splice square tube with angle bracket, come on.
Splice element sections with sheet metal screws
He took a great electrical design and JSed it.

[KB2WIG]

Is the design patented??


klc

[WA1GFZ]

I don't think so. The coolest part of the electrical design are the square booms that act as the transmission line.  The square boom has a lower impedance than round booms. The lowest z of round booms is around 100 ohms but the 1 1/2 inch square tubes spaced 1/2 inch is around 60 ohms providing better match to the elements. The square boom is also easier to machine. So once you have the square tube is is just a matter of deciding on the LPDA design constants for the bands you want to cover. Once you find the element lengths and spacing is is then just a matter of how strong you want to build the elements. I did double wall for the longer elements with about 50% overlap. The electrical design of the T12 is very impressive one small vswr bump at 22 mHz otherwise flat.  The only thing I changed in the electrical design was a more balanced length to diameter ratio for the elements.

[Pete, WA2CWA]

Is the design patented??

klc

There's actually a number of active patents for log-periodic type antennas. Do a Google for "log periodic antenna patented"

The log periodic antenna was invented by Dwight E. Isbell, Raymond DuHamel and variants by Paul Mayes. The University of Illinois had patented the Isbell and Mayes-Carrel antennas and licensed the design as a package exclusively to JFD electronics in New York. JFD made tons of log periodic TV antennas.

[K1JJ]

Yes, using a pair of square tubes to double as a boom and feedline is clever.  I used a standard round boom with additional angle aluminum to form the feedline. In the end it was heavier than the square boom after adding the feedline insulator plates. If I do it again I will use the square boom technique.

It will be interesting to see how Chuck's installation works out. There's no reason why it shouldn't be very FB.

Considering the quality of the existing kit, I would opt to cruise the scrap yards and pick up all the element tubing and square boom material I could find. Then fill in the gaps from Texas Tower's nice selection. Using Frank's suggestions for construction and the basic Tennadyne electrical design anyone could build a very nice log indeed.  

The overall element length to diameter ratio can be worked out too. I was able to get my variation within about 1% or less element to element. That took some doing.  IE, you want ALL elements to show a constant tapered impedance curve in the cell. With random L/D elements, some elements (the lowest impedance ones) will hog power while others starve - NG for the pattern and swr curve.

T

[WA1GFZ]

Once Chuck and I worked Dean 10 through 20 meters at 100 watts to compare performance between my set up and his stacked pair. It was an interesting test. 
I think I got my L/D ratio about 30% end to end. I thought I had added enough weight so quit there. Stock antenna is closer to 100%.
!/8 inch wall boom allows more load so it could be dialed in better.

[WBear2GCR]

Geez, sounds like you have to have some idea what you are doing... leaves me out!

[Steve - WB3HUZ]

Yes, using a pair of square tubes to double as a boom and feedline is clever.

Clever but not new. I used antenna like this in the early 80's that were already at least 10 years old then.

The reality is that most amateur radio beam (yagis, logs, quad, etc) are substandard in their mechanical design - especially the ones for the lower bands. Hams couldn't afford ones built correctly and/or companies couldn't make any profit at a saleable price.

[Todd, KA1KAQ]

Can't remember the nomenclature now, but Collins made some monster logs used b the military and gov't agencies to work all over the world reliably. Part of the design included the tower, a rotating design IIRC. Many of them were destroyed in place when it came time to remove them, but a few survive and some have made it into the hands of amateurs. SERIOUS bucks to move and install, of course.

[WA1GFZ]

Gee HUZ that is true. We have a couple logs at work with square tube feed. Also have seen commercial VHF logs with square tube feed. Not a new idea.
Yes Todd we had a good time pulling my 100 pound log up the tower. Then there is the 200 pounder Tom dropped. So 50 or 60 pounds is a lot easier to deal with. BUUUT, Sheet metal screws at element joints, that is H.A. Then 7 segments  on a 19 foot element with 2 inch overlaps
I assembled the first element and looked at the sag, I was ripped and got on the phone.

[K1JJ]

"19 foot element with 2 inch overlaps 
I assembled the first element and looked at the sag, I was ripped and got on the phone. "


X3 the element diameter for a joint overlap is plenty - and even that's overkill.  What was the el diameter for that 2" overlap?


From the element sag, sounds like he used a direct slide-in taper. (example: 1" to 1 1/16")  I always use a buffer sleeve to make it 1" to 1 1/8".  This results in a straighter element and according to YagiStress, good for ~ 100 mph with 1/4" of ice.


BTW,  Al Gore invented the square log boom in 1968.

T

[WA1GFZ]

yes Tom, He started with 1 inch and the last segment was a 4 foot section of 1/4 inch. All elements ended in a 4 foot section of 1/4 inch. Seems like a lot of work to make a JS element. I did double wall with 50% overlap. So longest element started 1 1/8 for about 4 feet. Then I slid in a 8 foot section of 1 inch. Then a 7/8 8 footer to just beyond the first joint. I put a 10-32 screw and lock nut. Then I used a 8 foot section of 5/8 and finally 1/2 inch to get to 19 feet.
I wanted to use as much as the stock material as I could. I did look at 1/4 inch steps and it did look very strong but I would not been able to use most of the element metal provided.
I would go with 1/4 inch steps if I was starting over. It would be lighter than the elements I have now.