405-Line VHF Aerials 2013 to the present day.

[G6Tanuki]

Yes, wooden dowels were sometimes fitted into elements to provide mechanical damping; without this, at certain wind-speeds the elements could be excited to mechanical resonance as a result of 'vortex shedding*'. Apart from an annoying hum conducted down the mast to the chimney [and causing night-time annoyance to occupants of the bedroom below!] the vibration could eventually cause mechanical failure. Weighting one half of the element removes the symmetry of the mechanical resonance about the feed-point, making it harder for wind-excited vibration to occur.

Some antennas used a length of cord threaded inside the element as a damper.

* Search for "Tacoma Narrows" on YouTube if you want to see what uncontrolled vortex-shedding can lead to!

[Peter.N.]

Thanks for the link, yes I remember seeing that before, quite spectacular. I noticed that in Caithness where they have wicked winds in the winter that most TV aerials are just a pole with a few bits of rod on, look a bit like a brussel sprout stalk.

The lighthouse keeper on the John O Groats road had a ham tower which was guyed about every five feet but only had wire antennas on it, one year he installed an HF tribander on a much shorter pole, the next year we went it was virtually tied in a knot.

Peter

[martinhog]

Hi, I spotted this array in Sherborne, Dorset at the weekend. It looked to be in quite good condition still. I believe that’s a band I, band II and a band 3 on the same mast. There was a similar array further down the road but in a poor state.

[Mr Hoover]

Sherborne was quite a fringy sort of Vhf area.
The Band 1 and Band 2 are probably
looking at Wenvoe (Ch5 Band 1).

The double 6 band 3 should be at the
same sort of angle for St Hilary Ch 10
but mechanically it's difficult.

Maybe the aerial is getting a mix of St Hilary
Ch 10 and Stockland Hill Ch 9 which had
much lower erp towards London to reduce
Co channel problems.Amazing how it has
all survived!

North Hessary Tor Ch2 and Rowridge Ch3
would also put in a fair strength there.

[lloydwells]

Taken today in Dumfries this town is full of them

[slidertogrid]

This thread has got me studying the rooftops! This is the only 405 aerial I have found so far, On a big old house in one of the older parts of Peterborough. The house is for sale so I don't know how much longer the aerial will remain, A lot of the bigger older houses get ripped out and made into flats so it may go.
In any case when I took the picture BBC 1 dipole was loose and seemed to be hanging on the connecting wire so it may drop before very long in any case.
BBC1 channel 5 in Peterborough came romping in all the old sets I sold to mates at school needed no more than a bit of mains lead splitting out to make a dipole Anglia was a bit more of a challenge and UHF especially if the set had a valve tuner needed at least a loft aerial.

[Paul Stenning]

I spotted this last week in Cardiff but didn't think to take a photo of it, so these images are from Streetview and aren't the best angles.

https://www.google.com/maps/@51.4714...7i16384!8i8192

https://www.google.com/maps/@51.4715...7i16384!8i8192

https://www.google.com/maps/@51.4714...7i16384!8i8192

I'm assuming it's FM (band 2) but not sure, so welcome comments.

I'm not sure how well it would work mounted vertically against the side of the building and so close to a metal streetlamp. It is pointing approximately north west so about 45 degrees off for the closest likely transmitters at Wenvoe and St Hilary (which are both west of the location).

[Heatercathodeshort]

Interesting Paul,
That aerial does not appear to have a 'TV' look about it. DAB radio comes to mind but as I'm not familiar with the area, I'm probably completely wrong! John.

[G6Tanuki]

It's much too big to be for DAB.

I wonder if it could be a low band mobile radio antenna for something like a link back to a taxi company??

[Paul Stenning]

The ground floor is a Chinese grocery store and there are no known taxi companies at that address or the address of the side entrance, but of course they could still have an office or something upstairs. Having said that, every taxi company I know of here uses mobile apps for their drivers now, not two-way radios.

It looks more like a 3 element FM aerial in style, but I don't know what size they would be to estimate whether this is about that size from the photos. It's probably not 405-Line TV though.

[G6Tanuki]

I was wondering what was downstairs. In my mobile radio 1980s past I came across quite a few unconventional (and Unlicensed) installations. Like a taxi company using Italian CB radios on 46MHz.

Unlicensed back-links were surprisingly common, whether for taxi companies or pirate radio stations


Always think of the obscure when the obvious has been exhausted.

[Restoration73]

There was an old system of community alarms on 107.9875 prior to the extension made
to Band II in 1989.

[Graham G3ZVT]

Here is a mysterious VP UHF aerial on a bungalow near here.

https://www.google.co.uk/maps/@53.52...7i16384!8i8192

Not a TV aerial for sure

[ntscuser]

Originally Posted by rambo1152

Here is a mysterious VP UHF aerial on a bungalow near here.

https://www.google.co.uk/maps/@53.52...7i16384!8i8192

Not a TV aerial for sure

It's not aimed at Ladder Hill (Group A, Vertical) then?

https://www.freeview.co.uk/help/cove...ostcode=M250DT

[Hybrid tellies]

That aerial in Cardiff is a bit of a mystery. Whatever it was or is being used for its performance is going to be degraded with its position near the side of the building. The aerial does not look that old but the coax run looks a bit shabby.

[Nuvistor]

Originally Posted by rambo1152

Here is a mysterious VP UHF aerial on a bungalow near here.

https://www.google.co.uk/maps/@53.52...7i16384!8i8192

Not a TV aerial for sure

Looks small enough for the old group C. We had a problem were I live that before analogue switch off the ITV mux could only be received if the aerial was VP. When switch over occurred and the power raised the problems was cured. The other muxes worked ok with either polarisation. There are still VP aerials on roofs here. Group C aerials are not much use now if the transmitter in use is Winter Hill.

One next door to me never been changed, looks wide band.

[Peter.N.]

There is an 'X' aerial in very good condition I passed on Tuesday in Wilmington Devon. Its half way down a long hill with its back to the transmitter which I think would have been North Hessary Tor I think it was to long for Wenvoe but it didn't have a clear view in that direction either. It's amazing how the Band 1 signal would bend into what you would think would be inaccessible places.

Peter

[Mr Hoover]

Originally Posted by Peter.N.

There is an 'X' aerial in very good condition I passed on Tuesday in Wilmington Devon. Its half way down a long hill with its back to the transmitter which I think would have been North Hessary Tor I think it was to long for Wenvoe but it didn't have a clear view in that direction either. It's amazing how the Band 1 signal would bend into what you would think would be inaccessible places.

Peter

Wilmington is virtually below the Stockland Hill mast.

[Peter.N.]

True but it must have been late arriving because all the early band one aerials were facing Dartmoor or Wenvoe, the one in question is facing Dartmoor or rather straight into the hill above Honiton

I passed it again yesterday and it is actually a 3 element complete as in your picture.

We moved here from Kent in 1970 and had just gone through the conversion to UHF, down here we were back on 405 again for a couple of years. Stockland hill wasn't on the eraly list of 405 transmitters as seen on the first superhet TV's i.e the bush TV22.

Although we are in Dorset we can see Stockland hill from here but you can't from wilmington, not from the village anyway.

Peter

[Mr Hoover]

Stockland Ch9 went on air in Spring 1961
when Westward TV launched.Power to the
East was much lower to avoid co channel
problems with London.
North Hessary Tor Ch2 was a little later
than Wenvoe Ch5 which started in 1952.