Antennas — M0VMZ

Two DX Commanders: the 9 m and the 12.3 m. Between them they cover everything I work, and the interesting part of this page is not either of them going up. It is both of them coming down.

They fell over

Both of them, in the same blow.

Nothing about that was bad luck. A telescoping fibreglass vertical is a lever with a very long arm and a very small foot, and it does not fail gradually. It stands, and stands, and then the load finds whichever part of the install was the weakest, and after that the pole is a thing lying across your garden.

The weakest part was mine.

After the blow. Photograph to come.

Putting them back up properly

What I got wrong the first time was treating guying as something you add to a mast, rather than the thing that holds it up. A single guy point two-thirds of the way up looks reassuring and does very little: it converts a bending failure into a hinge, and the hinge is now the failure.

The rebuild:

Change	Why
Two guy rings, not one	One ring makes a hinge. Two makes a structure
Three guys per ring at 120°	Wind arrives from wherever it likes
Proper ground anchors	The anchor is what actually fails, not the rope
Non-conductive guys	They're in the near field; metal ones are part of the antenna whether you meant them to be or not
Tension checked, not guessed	Over-tensioned guys compress the pole and buckle it

The rebuild. Photograph to come.

What can go wrong

Same grid as the one on portable, pointed at the garden. Eight things, sorted by how likely they are against what they cost.

One of them is not a guess. A1 has already happened, which is the whole reason this page exists — and an item you have observed is a different kind of entry from one you have imagined. Everything else here is an estimate.Which is the honest problem with a grid like this. Seven of these cells are opinions and one is a measurement, and the colouring gives no sign of which is which. Reading it as though every cell carries the same weight of evidence is the most common way to be misled by one.

Antenna failure modes. A1 is observed; the rest are estimates. A1 sat one row higher before the rebuild — moving it down is a claim about the guying, not a fact yet.

A1 sits at Possible rather than Likely because of the guy rings, the three anchors and the tension check. That is a bet, not a result. The next gale scores it, and if it comes down again the cell goes back up and the rebuild was wrong about something.

Ref	What happens	What it costs	Handling
A1	Mast comes down in wind	A weekend, and whatever it lands on	Two guy rings, three anchors at 120°, tension checked
A2	Guy anchor pulls out of soft ground	Same as A1, because it becomes A1	Anchors sized for wet ground, not the day you fitted them
A3	Ice loading on the wire	Bent sections, a season off the air	Rare here; drop the mast if it is forecast
A4	Mast contacts an overhead line while raising	Everything	Site chosen with the mast flat, then raised. Never near lines
A5	Water into a connector or the feedpoint	A slow, confusing loss you chase for weeks	Self-amalgamating tape, and inspect at every drop
A6	RF burn at the feedpoint	A burn, and a lesson	Do not touch a radiating end-fed. The high-voltage end is the far one
A7	It falls on something that matters	Money, or a conversation with a neighbour	Fall radius kept inside the garden, including the guys
A8	Corrosion in joints and radials	A drifting match you blame on propagation	Annual check; note the SWR so drift is visible

A4 is the only one that cannot be recovered from, which is why it sits in the corner despite being the least likely thing on the list. A8 is the sneakiest: it degrades slowly enough that you attribute it to conditions, which is exactly why the record sheet below asks for measured SWR with a date on it.

Coverage

Where each one is usable, not where it is resonant. Log axis — on a linear one every HF band collapses into the left-hand edge.

What to record for each build

The template, so the next one is comparable with the last:

Field	Why it is here
Configuration	Wire lengths, radial count, feed point, height
Support	What holds it up, and how it is guyed
Match	Measured SWR at band edges and centre, with the analyser named
Conditions	Ground, weather, what was nearby
Survived	What wind it has actually seen, and what it did
Verdict	Whether it would go back up the same way

The last two rows are the ones that matter and the ones most likely to get left out. I left them out, and then spent a weekend in the wet finding out why they were on the list.