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Reviews For: Tennadyne T12 Log Periodic

Category: Antennas: HF: Yagi, Quad, Rotary dipole, LPDA

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Review Summary For : Tennadyne T12 Log Periodic
Reviews: 7MSRP: 1020.00
Description:
10 through 20 meters HF Beam
Product is in production
More Info: http://www.tennadyne.com
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0074
WS7X Rating: 2023-02-15
Excellent Performance Time Owned: more than 12 months.
My T12 has been up 8 years now and I am still quite pleased with its performance. The SWR is still 1.3 or less on every band and I can hear better than any other antenna I've ever had. I also think the front to back is excellent and the beam width is not too wide. Considering that there are no traps and no motor to go bad, the T12 should last many more years. The only issue I had with assembly was I thought the mast clamps that came with the boom truss were kind of poor quality and I was sure they were going to just slide down the mast. I replaced the clamps and I also put a bolt thru the mast below the clamps just in case they do slide down. Other than that I'm a happy camper! See you on the bands!
N0UY Rating: 2013-02-13
Trying Something Else Time Owned: more than 12 months.
This is an update to my previous review. Although this antenna functions quite well on all five bands it was designed for, it is not as durable as I need at my qth here in Northern Minnesota. I have used it for more than ten years now but like clock-work I need to make repairs about every two years. I made several of my own upgrades to the mechanical aspect of this antenna and made a few of the ones recommended by Roger. This winter was not kind to the Tennadyne again this year so I have opted to go with a 6 band Mosley this spring. I think in other parts of the country and world for that matter the T-12 would be an excellent choice as long as you don't frequently have freezing rain or heavy snow combined with high winds. 73 Ray
W7DO Rating: 2011-11-08
Azimuthal Slippage Time Owned: more than 12 months.
My T12 is of the original design covering 20 to 10 Meters. Electrically, the antenna is a pleasure to use. The antenna is mounted at 70 feet on a crank up tower. My beef is even in less than moderate winds, the antenna slips azimuthally on the mast even with so called slip-knot devices. What needs to be looked at is a better boom to mast interface. The current design uses an insulator block that is tightened up against the mast. This insulator block ends up acting like a slipping clutch in the wind. Those putting up this antenna be very careful tightening the SS nuts and bolts on the mast/boom interface, as they are very prone to galling. Use penetrating oil and slowly tighten.
QRPNEW Rating: 2011-05-27
Needs a Redesign Time Owned: more than 12 months.
I have had this antenna for more than 3 years now.The elements keep on ripping out of the boom and falling off.

This has happened 4 times now on various rear elements. I just woke up this morning to go to work, and again found another element half laying in the drive way!

The electrical design of this antenna is superb, it just needs a better mechanical engineering.

The engineering on the boom, element mounting and all aspects of its mechanical design is marginal which is a real shame. I cant repair mine anymore because it has been repaired so many times before. The boom is a mush of cracks and weak aluminum.

I would buy this again antenna if someone like DXENGINEERING or M2 built it with the feedline boom. This aspect of the T12's design places it way ahead of other LPDA designs which use a simple crossed feedlines.

I have a buddy across town who has the M2 squared log and this T12 just leaves it for dead in on air comparisons. The simple M2 log has way too few elements and has the SWR bump problem near either 12 meters or 10 meters. You can easily find these spots where there is no FB ratio.

If you live in a tough wind or ice area I would avoid buying this antenna.

I have not decided what antenna I will replace it with. It might be a Optibeam, quad, steppir or TH11. I just need something thats reliable and does not fall apart in the air.



W4CCS Rating: 2009-11-20
WOW..!! Time Owned: 0 to 3 months.
I have operated my new T12-10-30HD for three weeks. This is by far the best antenna I have ever operated. Most DX stations return on first call..

Had a couple problems with the initial install such as holes not drilled. Minor stuff..!! Also, the center line balance point was about a foot up the boom from where the holes were drilled for the mast clamp. I did not relocate it but wish I had..

This antenna experiences a VSWR lower then 1.4:1 over the entire ham band (including WARC bands) from 10-30 MHz. Great performance. It really works well with Alpha 87A. I mounted this antenna at 140 feet (43 meters) and it is very quite also.

Would I do this again...?? YES.

Thanks Roger.

de W4CCS
W9CLA Rating: 2006-02-08
My Thoughts 18 Months Later Time Owned: more than 12 months.
Having logged 18 months experience using my new T-12 I am much more knowledgeable about the antenna and its performance as compared to my previous Telex TH11DXX. I made several minor mods to the antenna during the assembly stage most notably adding 48 black plastic end caps (24 small ones and 24 larger ones) http://www.mcmaster.com to the open ends of the elements. I used the small ones on the tips of the elements drilling a small .125 inch drain hole on the bottom side of each of the tips. The other 24 were used to cover the elements ends as they protrude through the two parallel boom sections. This was done to minimize the infamous singing attributed to this particular antenna design. Although it doesn�t totally eliminate the singing it does reduce the tendency and also prevents mud wasps from plugging up the ends of the elements. It is very important to drill that little drain hole in each element tip to let the moisture seep out or you will have a very bad experience in the freezing winter temperatures if ice develops inside the element.

I have one bone to pick with the design and that is the boom to mast interface. To be kind it is very flimsy. It�s probably adequate for the smaller logs like the T-8 but with a boom 30 feet long it just doesn�t work very well. The problem with logs is that you must maintain electrical isolation between the top and bottom parallel booms creating a challenge for the designer to develop an effective, yet mechanically strong boom to mast interface. The boom support provided by Tennadyne is a piece of light weight aluminum angle held by two bolts and it just does not work very well. The black UV resistant polypropylene rope that came with the antenna is supposed to attach to the vertical support and there is no tension adjustment possible once it is attached. I finally ended up re-designing the whole interface using square 6061 aluminum tubing for the vertical boom support and .125 inch Phillystran non-radiating tower guy wire with (4) turnbuckles for tension adjustment. I also purchased a sheet of .75 inch TORLON (Polyamide-imide) http://www.mcmaster.com and created a sandwich of two pieces of TORLON instead of the single piece of what looked like UHMW used by Tennadyne. By so I was able to attach the square tube boom support between the two sandwiched pieces and the two booms were also in the sandwiched assembly providing great mechanical rigidity yet maintaining electrical isolation. I can now adjust the tension of the boom supports to get the optimum boom sag once the antenna is up on the tower.

I really like the antenna and it has held up very well to high winds, ice etc. It sits atop a 72 foot US Tower high on a hill where it takes a lot of wind. The SWR is fairly constant without a lot of peaks and valleys that are typical of trapped antennas. My Alpha 78 in the no-tune position really likes that. Logs are inherently efficient, more so than a conventional trapped antenna. This is why Telex Hygain used a modified Log-Cell design philosophy when they designed the TH11DXX back in 1990. I was one of the 5 beta testers of the TH11DXX for Telex. In any event, the Tennadyne will not provide the kind of front to back or side lob rejection found in an 11db gain monobander it just isn�t in the cards but it works very well and very efficiently transfers the RF energy into the ether without burning up precious watts in high loss traps. I did not use the suggested Collins inspired coaxial choke balun suggested by Tennadyne but instead opted to use a Telex BN4000 (4000 watt current balun) which mounted very neatly on the front of the boom without having to have a big chunk of coax adding extra weight out front.

Would I buy this antenna again, you bet. In fact, we just bought a lake home in northern Wisconsin and as soon as I can get a small tower up there I will buy a T-8 for our place on the lake.

Craig L Anderson W9CLA
WW4US Rating: 2005-12-20
THE PERFORMER Time Owned: 6 to 12 months.
I had order a T-8 that I never took out of the box from Chuck in TX. I found out that Roger had bought the company ,so I called him to trade it for the T-12. Dealing with Roger was a pleasure. I installed the T-12 at 90ft and what a great antenna... swr are 1:11 across the entire band from 13mhz-29mhz.I've had in the past the TH-7 and 205BA and this is a keeper.... One antenna ,no traps, one coaxial cable ....and best of all ... no moving parts...Great price. If I had to do it again I would get the T-14 (This must be the Ultimate) Thanks for having a great product Chuck and Roger. 73 WW4US