Tag Archives: Tennadyne Anntennas

Replacing an old T-8 with a new Tennadyne T-8 at the K9ZW home QTH

[December 10th, 2017 – releasing this post that somehow never was added back in September]

 

What does a log-periodic (LPDA) antenna look like when a combination of wind-fatigue, corrosion, and some issues from a nearby lightning strike all come together?

 

The old T-8 after 20+ years of abuse missing elements and with broken boom-element interfaces.

 

The Old T-8 Being Abuse by Winter

My old second hand T-8 had seen better days.  Coronal arcing was from a nearby tree lightning strike.  Corrosion was caused by the previous owner having injected elements with some sort of spray foam sealant.  And the wind was the 20+ years of exposure, including some recorded high speed prolonged winds.  Sort of like driving the antenna at freeway speeds from here to Chicago and Back.

Vern K9EME was instrumental in changing out the antenna, as I had some very restrictive health limitations at the time.

 

The new improved T-8’as it was being assembled on the tower

 

We had a snorkle-lift to use and the replacement went very well.  The reason we assembled the elements after the booms were installed was how easy the lift made the work.

Also replaced was the choke-coil and feed line.

Again with many thanks to Vern K9EME, the K9ZW station returned to the air very quickly.

The corrosion that had set into the old antenna along with the effects of the lightning strike to a nearby tree made the old antenna a candidate for recycling.  No amount of effort could separate parts of the antenna, and other parts were powder.

Despite the abuse it had really earned its keep.  I really didn’t want to change it for anything else.

Since he took over the company,  Roger at Tennadyne builds his new antennas with MUCH thicker boom material, better clamps and hardware – all resulting in a new T-8 being a significant upgrade.

73

Steve
K9ZW

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Installing SlippNott Upgrades at K9ZW

The Tennadyne T-8 used two stainless u-bolts for attachment. In the highest of winds the large double booms of the Log Periodic antenna caught enough wind to slightly rotate on the mast.

To counteract this I decided to upgrade the T-8-to-Mast and Mast-to-Rotor connections with Tennadyne’s improved attachment method, the Tennadyne SlippNott.  (The much smaller T-28 Log Periodic doesn’t have enough surface area to need this upgrade.  U-bolts work perfectly fine for the smaller antenna.)

T-8 Original U-Bolt Clamp

T-8 Original U-Bolt Clamp

Another view of the original attachment. It had taken six years to pivot perhaps 10 degrees, though no matter how you look at it, it was moving even if very slowly.

T-8 Original U-Bolt Clamp

Original U-Bolt Clamp – Another View

The SlippNott retrofit upgrade uses two machined clamps with roughly one hundred time the surface contact area of the two u-bolts.

T-8 with SlippNott Retrofit

SlippNott Retrofit – another view

Another look at the retrofit in place.

T-8 with SlippNott Retrofit

T-8 with SlippNott Retrofit

I did the install from scaffold after lowering nd tipping over the whole tower.

Tower Access

Lower, Tilt and Scaffold

Also installed was a second SlippNott providing additional grip of the mast at the antenna rotator rotor unit.

SlippNott rotor installation

SlippNott rotor installation

This one was a fiddle to install given the restriction of the three nested tower sections.

Inside Nested Sections

Tight Quarters

Again it provides a huge increase in clamping action and limits the risk of the newly enhanced situation at the antenna twisting the whole mast in the rotor clamp.

Rotor SlippNott Installed

Rotor SlippNott Installed

A worthwhile project – wish the SlippNott was available when I put the tower and antennas up.

You can read more about them at the Tennadyne website – http://www.tennadyne.com

 

Direct link to the SlippNott page is http://www.tennadyne.com/slipp_nott.htm

73

Steve
K9ZW

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Spring Antenna Service

This winter and early spring have not been kind to outdoor equipment.

This weekend finally the weather broke and it has been nice enough to spend some time on the antennas.

Original plan was to do a lower, inspect, service & repair in a few weeks, but some obvious impact from exceptionally high winds has made it prudent to start now.

The two log periodics are on the same mast, and winds have tweaked the larger (T-8 10-20m) about 5-10 degrees from the upper smaller (T-28 1.3ghz-6m) most likely by slipping the larger boom.

My T-8 predates the “Slipp-Not” brackets that Tennadyne offers and a set will be on order (I make pick it up at Dayton).  This should reduce the chance of one antenna slipping in relation to the other.  Beam Width coverage is wide enough the little tweak is more an offense to me than it is to performance, so it may wait until the next lowering.

My Tri-Ex/Tasjian Tower has feedline stand-offs that I user large UV resistant o-rings as the cable retainers in the forked ends of the stand-offs.

Wind and time took out the second from top o-ring and the wild winds caused the feedline to be hooked about the clamp.  It is amazing to think how wild of wilds would be needed to raise that much triple-coax-feedlines-plus-rotor cable around enough to whip it about – must have been a monster wind.

The cable is not hugely at risk, but it would be better to get it back in place.  Again I will have to decide if I deal with it now or in a few weeks.

When the tower is lowered and tilted over I use a set of scaffold I bought from work – a handful of rings from a manufacturer long out of business that don’t connect with any other brand (not that you should).  Useless for work but just what I needed and makes an ultra safe work platform.

WHen it comes down next the coax seals will all be inspected and renewed as needed, each cable gets a visual and wipe down, plus gets a check with the TDR for any electrical problems.

I have upgraded lightning protection that will get installed.

A decision to be made is whether to swap out the rotor (a Ham-IV) for a freshly overhauled Ham-IV or whether to leave well enough alone.  Plan was to swap in the fresh overhaul and then have the long serving unit overhauled as the spare.

Decisions will hing on whether I can disengage the displaced cables for now (I lower the mast but haven’t tipped it over yet) or whether I need to hand crank the tip-over now.

It is also time to get the buried feedline in to do a second HF antenna on most bands.  Originally I was going to make the vertical just another setting on the remote antenna switch, but I am now thinking it should be on the second feedline to the shack so two can be used at the same time.  The Flex-5000A could use the dual antennas now and the Flex-6700 will take the diversity capability to a new level if I get my antennas sorted out correctly.

At least it is warmer out once I figure out the plan!

73

Steve
K9ZW

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REPOST – Fishbone Aluminum Wedges – Tennadyne Log Periodic Anntenas in Action

When faced with the decisions on what antennas to install I had a number of things to weigh up:

  • Cost was a consideration
  • Directionality a strong desire
  • Gain a consideration
  • QRO (Higher Power) Capability desired
  • and the big issue – boom & swinging radius a concern
  • The recommendations I was soliciting from other Amateurs led to a wonderful short list of possible antennas, but simple availability first led me to consider the Tennadyne Log Periodic Antenna .

    One of our club retired members had become infirm and wanted someone to buy & take down his antenna & tower. This fellow has a past history of Elmering me in his profession when I was just out of high school, and I made him an offer & worked the deal out of respect for him. I figured I could help him out and either use or trade the tower & antenna for part of what I wanted.

    In the deal I ended up with his year old Tennadyne T-8.

    The short list of antennas I had was huge. I had been offered a very large Mosley 96x but found that it would swing off my property due to tower location.

    With this antenna & that antenna being set aside as too expensive, too big, too long of a wait or for concerns over performance, the research on the Tennadyne T-8 lead to my determination to put it up and see how it works!

    Wanting to have a directional 2m/440cm antenna, I purchased a Tennadyne T-28 (Original Model) which is a 6m to 1.3gHz Log Periodic, and stacked it 11 ft above the T-8.

    Here is the installation (before cables were installed):

    Stacked Logs at K9ZW

    To date I’ve worked 98% of the time with the T-8. I’ve found it’s performance to be much better than I had imagined. Side and back singal rejection is impressive, allowing my listening to focus in the direction the antenna is pointed.

    The measured Standing Wave Ratio (SWR) is 1:1.25 or better across the T-8’s advertised range of 20m to 10m.

    Received signal reports have been excellent, with how many dB over 5-9 usually the only number that changes by the QSO!!

    Listening is exceptional in the direction of the antenna’s focus, though of course it is not Omni Directional in listening. In some situations the T-8 may be well suited to being paired with a “listening antenna”.

    The little bit of experimentation I’ve done with the T-28 has shown great promise for this smaller log periodic, and I am looking forward to putting it to the test down the log.

    It goes without saying that I would highly recommend the T-8. Simple, cost effective, Mil-Spec style build, and great performance make it an antenna worth looking at!

    73

    Steve
    K9ZW

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