Top Band Verticle

There is nothing new about a 43m Verticle for top-band. It is just a 1/4 wave verticle - but it is 43m tall !! This is the issue.

Proposed Solutions

  • Thoughts
    • Steel pipe
      • You would need 8 at least
      • Too Heavy/Difficult to join here in DU Land
    • Steel Pipe with Spider Pole
      • We did this before... but we are limited to 24m
    • Use my tower
      • Spider Pole
      • Slight extra height
      • Possible...

Use my tower

Firstly My towers (I have 3 of them), are crank up, and tilt over. This was done for Typhoon protection, and to remove the need to climb towers.

The tower dimensions are

  • Section Length 8m
  • Number of Sections 3
  • Overlap per section 1m

At the top of the 3rd section there is a rotator plate, and a thrust bearing (like most towers). This rotator plate is 1m beneath the top of the tower.

The verty top of the tower is therefore

  • 8+7+7
  • 22m

I then remove the short Yagi pole - and replace it with a 2" 5m pipe - 4.5m long (from my local hardware store), accounting for the placement of the rotator plate.

  • 22+4.5-1
  • 25.5m

Then using the first 70cm of the 2" pipe as an intenral support for the Spider polei. To do this I welded a 'cross base plate' (no clue what this should be called) and place an 18m SpiderPole there

  • 25.5 -0.7 +18
  • 40.3m

Side View

This sshows you the design of the towers - and the pole. Note The tower has a Metal support out of camera view - it is NOT resting on the support on the right.

Cross Base Plate

This was the easiest (and cheapest) solution I could think off. It is just some spare rebar.

Spider Pole fitted

We cut a hole in the top of a plastic cover - so the spiderpole did not sit directly on the metal.

Added a Mast Spreader

With the Wire wrapped around the spiderpole - we wanted to keep the wire away from the metal tower. So we used a 'yacht mast spreader' from a piece of water pipe.

Base of Tower connections

At the base of each tower there is a seperate 7/8" Heliax cable. So we just patch into this existing cable - and bring the signal back to the shack.

Ground

We ran sixteen 20m ground radials. These were all attached to a metal baseplate - which was then grounded.

Previously we have run longer radials, however we could not detect loss of performance.

Tuning

I ran a Nano VNA as to get this SWR Plot.

You can see it is very sharp but it's where we want it to be.

So how do you get 43m onto a 40m verticle ?

The spider pole we put aprox 2 turns per section of wire - to use up some extra wire.

Lessons learnt

Although a crank up tower is a compromise - it is very useful for quickly changing your antennas. I have not tried shunt feeding it - but as the connections depends on rollers - I have a feeling it would disappoint.

One added benefit of a crank up - is assuming you are too long (which we were by aprox 30 cm).. you just lower the tower, and trim a little....We also had probably +30cm we could have gone up, had an extension been necessary.

Dig in Ground Radials... it will be less hassle and grief in the long run.

Sadly TX on Tx is not the most difficult part - Rx is.