High Gain DX Aerials, group, not Wideband

watty

Are Hirschmann aerials gone? I know Triax owns Hirschmann now, and when I look at highest gain aerials on Hirschmann German Site, they are similar appearance to the Kathrein Olympia.

To be honest both the Unix 100 and the Kathrien Olympia seem a bit flimsy.

Is the Unix 100 (not really 100 element, more like 22 or 25) and the Olympia the peak of Aerial thechnology these days?

I'm not interested at all in so called High Gain yagi Wide Band 21-68 aerials. Unless it is a Log Periodic, my religion forbids me to beleive such abominations exist. Beside a Wideband aerial would not at all suit what I want.

I want separate A, B and C group aerials. Very high gain.

I'm also using a small aerial for Clermont RTE, it is very poor on TV3 & TG4, even though I can see the mast clearly. It is old. perhaps it has corroded into a Group Cish only? (TV3 & TG4 are close to top of band, RTE1 &2 somewhat lower). Also why is RTE1 got bad ghosts when aerial is in free space and nothing inbetween to TX sight? Clear LOS. Duff aerial? I replaced the feed cable.

Any suggestions?

BBC1, BBC2, UTV, C4 nearly as good as TG4! Five from Blackmountain is very bad with herring bone. Is there an Irish TX close to that channel?

Location just south east of Dundalk.

Ulsterman 1690

Five from Blackmountain is very bad with herring bone. Is there an Irish TX close to that channel?

Tee Vee Tree from Dublin is on Ch 35 but that shouldnt cause any issues

More likely its Co Channel interference from an English Ch 5 transmitter (or maybe IOM Cant remember if they use Ch 37 )

lawhec

Two aerials that I've used for high-gain with decent success are the Blake DMX10A and Televes X Type 8042. Both are UHF Group A aerials that have helped bring in DTT from Brougher Mountain where the current aerials wern't up to the job.

The Blake one is in an attic feeding a bedroom DTT receiver. AFAIK it was the first aerial to get a CAI standard 1 mark a couple of years ago.

http://www.blake-uk.com/prod_products_aerial_DMX.aspx
http://cpcireland.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=AP01123

The Televes aerial is on an outside roof on a house in the souther edge of the Sperrins, on the outer service area of Brougher Mountain - analogue was fine on the old aerial but less than half the multiplexes were coming in clean. It looks rather flimsy and a potential disaster for wind load when you first see it, but in the three years it has been up not one element has came off it. Gain is measured at 16.5db which is high, but doesn't indicate dbi or dbd. When installed and downlead replaced with CT100, pictures became rock solid.

http://www.televes.es/ingles/producto/ficha.asp?COD=232
http://cpcireland.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=AP00764

I want separate A, B and C group aerials. Very high gain.

Would I be right assuming that A is for most of Divis/Black Mountain, B for Mux C from Divis and C from Clermont Carn?

I'm also using a small aerial for Clermont RTE, it is very poor on TV3 & TG4, even though I can see the mast clearly. It is old. perhaps it has corroded into a Group Cish only?

Probably more the case that many aerials seem to perform poorly at the top ends of the band, small yagis, particulary unbranded wideband ones but sometimes even C/D grouped, can have a fair bit of fall-off compared to RTÉ1 & 2 which are further from the edge.

Also why is RTE1 got bad ghosts when aerial is in free space and nothing inbetween to TX sight? Clear LOS. Duff aerial? I replaced the feed cable.

Is there local hills or tall buildings to the side or behind the aerial? If not, could be a mismatch between the aerial and downlead.

BBC1, BBC2, UTV, C4 nearly as good as TG4! Five from Blackmountain is very bad with herring bone. Is there an Irish TX close to that channel?

Probably co-channel with the Five transmitter from Cambrett Hill in Dumfries, Scotland. Often gives trouble along the Antrim and Down coasts for people trying to receive Five from Black Mountain, particulary on high pressure days.

watty

Where do you buy Televes stuff? I can't get the UK agent to reply, when I ring they give me an email address, my emails never answered.

I'm suspicious of aerials that don't have a balun. Though I find making the connection "Y" from coax about 2" long improves match.

Thanks for quick feedback. It could be Three Rock on Ch37 the view that direction is clear.

I want to see is a B or C/D better for C48. A Group "B" should be better. But I don't get a whiff of it.

The BBC1 & BBC2 are about 3dB or more better on the Group B aerial than the Group A. Again, the Group A ought to be fine. Group A is a Kathrein Olympus with a Fringe GroupA preamp and GroupB is a UNIX100 with a Fringe GroupB preamp.
I have a two sets of channisled filters, one for all the analogue channels and one for all the MUXes, one helical filter and gain pot for each channel except the two adjacent DTT muxes share one filter, but the Divis feeds are not strong enough to split with a passive splitter. I don't know which gain of preamp I have.

The aerials can't be combined at all without the filters. Each aerial on its own gives cleaner signal via the filters than direct. IMO the channised filters are definately a must for either better intermod / less noise on a distribution system, or for combining aerials. A bit pricey for a private house perhaps at €350 for 9 channels.

I'd have thought Five from BlackMountain impossible on most of the Antrim coast. My mother on Islandmagee never got Five till she got Sky.

watty

Where do you buy Televes stuff? I can't get the UK agent to reply, when I ring they give me an email address, my emails never answered.

I'm suspicious of aerials that don't have a balun. Though I find making the connection "Y" from coax about 2" long improves match.

Thanks for quick feedback. It could be Three Rock on Ch37 the view that direction is clear.

I want to see is a B or C/D better for C48. A Group "B" should be better. But I don't get a whiff of it.

The BBC1 & BBC2 are about 3dB or more better on the Group B aerial than the Group A. Again, the Group A ought to be fine. Group A is a Kathrein Olympus with a Fringe GroupA preamp and GroupB is a UNIX100 with a Fringe GroupB preamp.
I have a two sets of channisled filters, one for all the analogue channels and one for all the MUXes, one helical filter and gain pot for each channel except the two adjacent DTT muxes share one filter, but the Divis feeds are not strong enough to split with a passive splitter. I don't know which gain of preamp I have.

The aerials can't be combined at all without the filters. Each aerial on its own gives cleaner signal via the filters than direct. IMO the channised filters are definately a must for either better intermod / less noise on a distribution system, or for combining aerials. A bit pricey for a private house perhaps at €350 for 9 channels.

I'd have thought Five from BlackMountain impossible on most of the Antrim coast. My mother on Islandmagee never got Five till she got Sky.

watty

P.S. Why do they insist on calling a yagi with reflector + feed + 9 directors (=11 elements) a 48 element aerial. The UNIX100 certainally has not 100 elements.

It's like Humpty Dumpty, words meaning what ever they like.

Seems they count every spike and rod as an element which is madness.

A good sanity estimate (apart from real dBi or dBd gain) is number of wavelenghts long. About 2.5 x wavelength for boom length is the point of vanishing returns on gain vs size, such that you need an array or giant dish to get more gain.

watty

Two of these stacked (more robust than X type?)
http://www.blake-uk.com/prod_products_aerials_SR.aspx
SR18 will give 15dB to 17dB gain depending group.

One of these
http://www.blake-uk.com/prod_products_aerials_JBX.aspx
JBX21 will give 14.53 dB gain

I'm assuming the SR series cheaper than JBX21 series?

Who sells them or do I order direct?
I notice that Blake list *REAL* numbers of elements as well as ficticious numbers!

Ulsterman 1690

I'd have thought Five from BlackMountain impossible on most of the Antrim coast. My mother on Islandmagee never got Five till she got Sky.

It comes pretty well in most of Carrick although not in Whitehead or Larne

watty

I tend to think of Carrickfegus as mouth of Belfast Lough. but of course it is the Antrim coast. Growing up in Antrim, I tended to think of the Antrim coast as being from Larne to Coleraine.

SPAWKER

watty,
As far as I know Wescos in Drogheda still stock Hirschmann aerials,although it is nearly a year and a half since I last bought one down there.Their phone No. is 041-9836571.

lucernarian

You can indeed get Hirschmanns in Wescos in Drogheda but I think the cost is in the region of €100. Open to correction on that though.

SRB

Watty, have been through 2 Televes in the last few years, now to be fair, I'm on the coast and it sure does get windy here, but neither of them lasted a winter. In fact the town is scattered with bits of orange televes elements after every storm. I know a few friends on the Antrim coast have CH 5 from Scotland, though it does suffer Co Channel from Black Mountain from time to time.

watty

Thanks. The Blake aerials look interesting. The Televes folk only seem to do wideband/moderate gain.

I think a pair of 18 element aerials may be more robust, higher gain and lower cost than a single top of range Hirschmann, Katrein or Unix100. I will try this approach and see.

watty

Thanks lads. The Blake people very helpful (once they established my Qty requirements!).
Even from a distributer I think their stuff should be competitive. I think they used to sell the famous J-Beam yagi in pre cable days.

Mayo Exile

Watty, you say you are southeast of Dundalk. Are you anywhere near that new hotel that is going up? Its the tallest structure (14 stories or so), along with the wind turbine, by far in the entire area. Could that be the cause of your ghosting?

watty

No. Good guess though. It is more to west of my path. I'll try a different aerial with higher gain and an attenuator.

dmm1000

will you let us know the details and results of how your install goes Watty ?

Rippy

watty wrote:

I'm also using a small aerial for Clermont RTE, it is very poor on TV3 & TG4, even though I can see the mast clearly. It is old. perhaps it has corroded into a Group Cish only? (TV3 & TG4 are close to top of band, RTE1 &2 somewhat lower). Also why is RTE1 got bad ghosts when aerial is in free space and nothing inbetween to TX sight? Clear LOS. Duff aerial? I replaced the feed cable.

Any suggestions?

With clear LOS and a strong signal, how about using a log periodic? Far more directional than a yagi and and a flat response accross the band. I use Vision logs from Vanjak in Derry,
http://www.vanjak.com/products.php?category_id=493
Very well made and excellent performance.

watty

You would need a bigger log periodic than is normally sold to get the gain.
Log periodics for same size are 3dB to 6dB less gain, but indeed true wideband.
But for DX you want to have narrow band aerials to reduce pickup of unwanted signals and reduce intermodulation products and thus S/N.

It isn't actually more directional. For same size its less directional, but no side lobes. Yagi aerials have multiple "lobes". sometimes with a yagi the best picture is when a co-channel is in direction of null between two nodes.

It's a very complex subject.

For Ultra wideband directional aerial you can't beat a Log Periodic. The Military have big ones for 1MHz to 30MHz and 30MHz to 2GHz.

For non-directional wideband the bi-conic is the business, rarer than the more common discone which is 1/2 the size and derived from it. No Gain though.

The worst aerial is the omnidirectional Halo for horizontal polarisation. It can be 6dB less than a omni whip for vertical polarisation. You see them stupidly used here for radio. In UK originally VHF FM Radio was horizontal polarised. Most stations in UK and practically all here are now slant or vertical so that a car aerial works (Whip). Halo is only aerial in widespread use with negative gain. They are also a worthless waste of money. A simple cheap 1/4 whip will work better.

gerryo

watty wrote:

The worst aerial is the omnidirectional Halo for horizontal polarisation.

I seem to remember seeing these (in pictures) used for car antennae way way back. They looked like a folded dipole that was bent around a cylindrical former, then mounted on a short mast above the car body.

watty

That's them. Lots of them on so called professional TV /Radio combo installs. There is indeed a TV version in plastic flying saucer housing for coaches / buses which makes some sense. You also get them on caravans which is stupid as you can't be in a caravan when it is mobile. A regular aerial & dish clamped to towbar when parked is better.

Antenna

watty wrote:

Also why is RTE1 got bad ghosts when aerial is in free space and nothing inbetween to TX sight? Clear LOS. Duff aerial? I replaced the feed cable.

For the ghosting on RTE try a Grid aerial (AKA 'ColourKing' or Bow-Tie Array) instead. With Vertical polarised signals (the case here), Grids would be generally more immune to ghosting than a standard Yagi.

The ghosting would not be unexpected if you are near an industrial area with tall metal structures?

Antenna

Ulsterman 1690 wrote:

Tee Vee Tree from Dublin is on Ch 35 but that shouldnt cause any issues

More likely its Co Channel interference from an English Ch 5 transmitter (or maybe IOM Cant remember if they use Ch 37 )

Interference from another C5 tranmsitter would cause a Venetian Blind effect, not a herringbone pattern (which Watty says he has). The Precision offsets between co-channel transmitters causes a distinctive very fine 'Venetian Blind' interference effect.

Maybe it is interference problem from a modulator in a VCR or satellite receiver on another channel?

watty

Hmm.. A modulator even 1/2 a mile away is indeed a likely source. If the aerials are connected wrongly at an old VHS etc.

lawhec

Televes' aerial market seems to be concentrated these days on the DAT 45 & 75 both of which are wideband but if you track down hard enough you can get grouped aerials from them. As SRB points out they look dangerously flimsy, I think the aerial I've istalled has been lucky so far.

I agree that the FM "halo" is an abdomination. And especially since most FM radio signals in the Irish Republic are vertical only and all have a vertical component, such an aerial is self-defeating.