High gain group A Aerial for Divis

Finne1993

Hi all, I'm hoping for a few suggestions to a little problem i'm having, I live on tip of the Cooley peninsula in Louth and currently get my BBC/UTV/CH4 from the Kilkeel relay, signal perfect but no freeview because as we all know Divis is the only option available for the next 3-4 years until the switchover is complete. I was told a few times by different installers that it would nigh on impossible to receive the Divis signal from where i am due to the Mourne mountains being a fairly large obstruction in front of me, none the less since i started doing a few aerial and satellite installs a few different impossibilities have popped up in front of me and i decided to try it out, i armed myself with a basic 18 element group A contract aerial (similar to the one pictured below) amplified with a fringe A1228 28db masthead amplifier



I got a fairly good picture on analogue Ch4 and UTV, BBC2 was ok and BBC1 was poor 21,24,27,31.
I then got my hands on a DC Quad8 Aerial (pictured below)

It improved the picture a bit, Ch4 and UTV were nearly perfect but the BBC's didnt improve much, i also got a digital signal on Mux A(Ch 23) and Mux B (Ch26) but nothing after that and the signal was approx 40% on Mux A compared to about 20% on Mux B, there was a slight movement on Mux 1 (Ch29) but not enough to get a scan started.
So you can see where this is leading, what is the explanation for the channels lower in the scale having a far better signal than the upper ones? According to numerous sites I've looked up, the group A aerials are increasing signal gain all the way up to Ch35 and only then do they start losing gain fairly rapidly so if thats anything to go by the signal strength should be an awful lot higher in the BBC channels and i should get a decent signal on Muxes 1,2 and D instead of getting nothing at all. I was looking at a longer aerial but would it really make that much difference?



This is an ABC DC Quad 11F Group A aerial and I'm thinking of buying it or even a longer one, might not look much different than the one above but there is an extra bar on either side of the reflector and it is an 11 element rather than 8, does anybody think it would make that much difference? would it somehow explain why the signal from the upper channels on group A are poor, I have my own doubts about that because another installer told me the longer the aerial or the more elements thats on it can sometimes reduce quality so hopefully someone can set me straight and advise me on this.
Just to note this was all with the aerial attached to a 6ft pole on the balcony out the back of my house, when i raised it up approx another 10ft it made little or no difference.

Sorry if it was a long winded post, i just wanted to get all the facts across clearly.

sesswhat

I can't say if spending more money on aerials would be worthwhile, especially if you could have a guaranteed Freesat service up and running for a similar price.

Of course Freeview has some different channels and works with cheaper IDTVs and PVRs. And then there is just the challenge of knowing you are almost there:D

Of course things could change after the switchover but that's nearly four years away. A long shot might be to try Caldbeck in Cumbria, which will be completing digital switchover and turning up the power this summer.

Finne1993

How right you are! Its the challenge more than anything else that interests me here, i have sky, freesat, digitalb etc, its just knowing i'm so close to getting a result here thats keeping me going. There must be a way and it would be so helpful if someone could give me some sort of explanation as to why the channels higher up the spectrum of group A have a weaker signal when they should have the strongest ones, its all a bit baffling to be honest!
I read in a different thread Watty started a few years ago http://www.boards.ie/vbulletin/showthread.php?t=2054999784 that he was getting a stronger signal on the higher group A channels on a group B Aerial, I have a cheap 18 element group B aerial here so I'm gonna try it out and see what happens, not expecting miracles though!!
And if i can get this working here, it means i can offer the service to other people locally with a simple aerial upgrade and give them Dave, Virgin1, Sky Sports News, etc FTA.

As for Caldbeck its nearly 3 times further away from me than Divis is and its likely I don't have a clear line of sight because of the Mourne Mountains and that would be essential to even get a sniff of a signal at that distance. Thanks for the suggestion though.

Anyone got any other suggestions or explanations!!

championc

My guess why you are having problems with BBC1 and BBC2 is due to cross modulation from Three Rock. BBC2 is on Channel 27, RTE1 on 29, BBC1 on 31 and RTE2 on 33. If you get a Notch Filter from Triax for Ch 29, my guess is that things will improve. This is what I needed to do on mine in South Dublin.

You could test my theory by either.
1. You could get a sheet of tinfoil and wrap it over the rear elements to block Three Rock signal. You would need to shield the masthead amp too.
2. What is RTE1 like on Ch 29. My guess is that you watch RTE's from Clermont Cairn ?


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Finne1993

Thanks for the reply, its a bit of a complicated set up that i have!! I currently pick up my BBC's from the Kilkeel relay and i also pick up my RTE1 (ch41) and RTE2 (ch44) from the same aerial from the Greenore/Carlingford relay, my TV3 and TG4 is coming from Three Rock on the higher channels 62 and 59, the signal is far stronger on them than 35 and 55 and it also means I'm using the correct group aerial (C/D) for the DTT. My view of Clermont is obstructed by The Cooley Mountains so its a no go for me and the only reason i want signal from Divis is for freeview.
It makes sense what you're saying because sometimes when i rise the aerial for Divis up higher the picture can slightly worsen rather than improve, and i can pick up all the freeview muxes except 1 and 2 which surprise surprise are on channels 29 and 33!! its starting to make a bit of sense now!!
Can you receive all the Freeview muxes or are you just using it for analogue?
A notch filter will hardly sort that problem out will it? i just did a little reading up on them there and they only block out channels either side, would be no good for the same channel problem, i'm sure there must be some other gadget that will do the job? I'll try out that tin foil solution and see if it improves the situation but i can't see it bein a long term solution!! thanks for the reply, bit by bit i'll get there! i'll post any more info i come across

championc

Years ago (about 25+) RTE made a box called a T6SA. It was white box about 4in x 2in x 2in and had two cables coming out the top. This was essentially a notch filter to reduce the strength of Three Rock channels 29 & 33.

Many years ago (about 15) I got Triax to make me a specific filter to knock out channels 29 + 33 (not 29 to 33). I live about 2 miles away from Three Rock and view my BBC's and ITV's (analog) from Divis on Group A. I don't reckon I'll get Freeview until they start to wind up the power a bit.


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Finne1993

So i take it the analogue picture you have at the minute is'nt great then?
If i got a filter to knock out channels 29 and 33 would it not knock out them channels no matter where the signal is coming from?
Maybe i'm wasting my time trying to get them am I?
The only thing in my favour is that i'm probably as far away from Divis as i am from three rock but i've an obstructed view of Divis while i've clear LOS to Three Rock so naturally the signal is going to be stronger, suppose all i can do is just keep messing about with the set up and try different amps, aerials and filters!

championc

In Dublinalong the coast, people get decent reception from Kilkeel even though technically they shouldn't (based on the power of the transmitter). It appears that signal travels very well over water.

I agree that you certainly don't want to be blocking 29 + 33 then and so the only possibility is to locate the back end of the aerial backing onto something like a chimney which could naturally block Three Rock's influence.


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Finne1993

sorry, you picked me up wrong, I meant to say the analogue you receive from Divis must be poor. I know from reading other threads that a lot of people in Dublin get their BBC and UTV from Kilkeel, the power its transmitting at is 500W, thats fairly high for a relay so theres no reason why with a bit of amplification it should'nt work along the coast of Dublin, I'm looking directly across carlingford lough at the Kilkeel mast so I get a decent picture even with a co ax cable stuck out the back of the tv, any sort of aerial pointed in any direction gets me perfect pictures.
Its just nosiness thats keeping me interested in Divis, I'm amazed I'm getting any signal from it at all with the Mournes directly in its path but I'm gonna crack it and get all the freeview channels eventually!! I just need to do more testing, thanks for your suggestions, I'm gonna try the tin foil effort first and see how much difference it makes, hopefully i'll get messing at it tomorrow and i'll post my findings!

championc

From the beginning I became determined to go the Divis Group A route despite everyone telling me I was Mad !! Anyway, I have pretty decent reception (slightly grainy) but I've got full Teletext so it can't be that bad.. Signal travels in an Arc like a rainbow rather than in a straight line so this could explain as to why you get the Group A signals. If you were nearer to the foothills then you would probably be stuffed.

Another suggestion to block signal would be to place a flat piece of lead behind the signal collector (won't catch the wind as much as anything else). Lead is an expert blocker.

I should have said before to also mask up the masthead amp. Signal can leak in there and be amplified that way too

Can't wait to hear how you get on !


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watty

4 x 18 elements in a quad layout gives best gain for the money and robustness.

you combine each pair with splitters (all 4 coax exact same length) and then the two splitters with a splitter.

I compared this at Dundalk with largest most expensive Triax and Kathrien "beams" and much better signal.

There is an optimal spacing for the four aerials and it works out 1/2 the price.

Finne1993

championc wrote: »

From the beginning I became determined to go the Divis Group A route despite everyone telling me I was Mad !! Anyway, I have pretty decent reception (slightly grainy) but I've got full Teletext so it can't be that bad.. Signal travels in an Arc like a rainbow rather than in a straight line so this could explain as to why you get the Group A signals. If you were nearer to the foothills then you would probably be stuffed.

Another suggestion to block signal would be to place a flat piece of lead behind the signal collector (won't catch the wind as much as anything else). Lead is an expert blocker.

I should have said before to also mask up the masthead amp. Signal can leak in there and be amplified that way too

Can't wait to hear how you get on !


C

If you have full teletext then you must have some of the freeview channels also, during my experiments i could never say i got a perfect picture but always got a watchable signal on muxes A,B,C and D. I'm gonna start messing about with thie set up now but i need a bigger group A aerial, I was let down with the one i was supposed to get today. If i get time I'll post later how i got on, not sure about the lead thing, the weight might be a bit of a problem!

Finne1993

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watty wrote: »

4 x 18 elements in a quad layout gives best gain for the money and robustness.

you combine each pair with splitters (all 4 coax exact same length) and then the two splitters with a splitter.

I compared this at Dundalk with largest most expensive Triax and Kathrien "beams" and much better signal.

There is an optimal spacing for the four aerials and it works out 1/2 the price.

What do you use the 4 aerials for Watty? Clermont, Three Rock and 2 different ones for Divis is it? Where did you get the 18 element quad? I was gonna get the DC quad 11F, would I be better off getting an 18 element one? A crappy 18 element cheapo group B aerial i got for a tenner got me a 45% signal at night on Mux C (Ch 48) and that will do me rightly so its basically the group A that needs improving, Muxes 1 and 2 to be exact.

championc

I think watty meant an array like group of 4 mini-aerials using combiners to make one big one. Personally I have a Group A Triax 100 Element.

As for the lead, I only leant a flat piece about 2" x 2" so not much weight in that


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watty

No
I meant a bracket to mount FOUR ordinary (but good quallity, baluns built in) 18 element yagis in what is called a quad layout.

Far superior to the Triax 100, which I tested.

championc

Hi Watty

What brand and model aerials did you use ? I assume the baluns you refer to are the combiners ?


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Finne1993

Sorry about being so naive about the quad layout suggestion, i'm still somewhat of a novice in this game!!
The tin foil experiment was a no no!! made no difference at all, I think its a better aerial and more amplification i need, I'm gonna look into wattys suggestion now and do a bit of googling and hopefully a few ideas will crop up, you'd hardly have a picture of your own set up Watty would you?
I still think if i had a better aerial with more elements and possibly a stronger amp i'd get enough to pull in the freeview muxes 1 and 2, thats all i'm struggling for at minute but at the same time i don't want to be spending silly money on an extravagant aerial that possibly wont make much difference.
Thanks to the both of you for the suggestions, I'll keep messing about with it, and hopefully get a new aerial next week and post any results i get!

championc

One thing to bear in mind - with all signal you have noise so the more you amplify signal, the more you amplify noise too. Your best bet is to have a variable amplifier (I have a Triax TA34A). The one thing NOT to scrimp on is your down cable. Don't use any of the washing line type cable. Watty, should we use RG6 or RG59 or ....... ?

You want as much of the signal you collect from your aerials to reach your TV or STB


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watty

RG6 or CT100 / PF100 etc..

RG59 is OK for VHF TV, DAB, FM Radio. Not UHF, except for patch cords at setbox or TV.
Amplifier is really only for cable loss. You can calculate the cable loss online for the length and highest frequency and then set amp no more than 3dB higher (or 6dB if the splitters combiners for four aerials are 1dB each).

As a rule of thumb:
Limit of diminishing return on size of a single aerial is 2.5x wavelength (about 65cm at 470Mhz/ A and 30cms at 860MHz D).

The makers count every spike as an element now. A so called 100 is more like 23 elements. >< on boom is NOT 4 elements but ONE. Also there are two broad design classes of Yagi, "normal" and "sparse". The number of elements on a "long sparse" yagi can be 25% less but the gain the same. It's really the length that sets the gain, not the exact number of spiky bits. Each "position" on the boom is really only one element no mater how they may market them now.

The mast amp should be at least 1.2m below the aerials and never in front to avoid feedback.

Too much gain in amp and local interfernce or channels even at other end of band will cross modulate and you get herring bones.

Antenna

Finne1993 wrote: »

The tin foil experiment was a no no!! made no difference at all, I think its a better aerial and more amplification i need,

The co-channel interference you mention from Dublin on 29 and 33 could well be mainly reaching you be reflections from large metalic objects (such as a factory etc) in the distance to the front of the aerial. Also ' more amplification' will do nothing to lessen co-channel interference.

Finne1993

Yes, i am using RG6, its all i ever use, no point scrimping over cable that only costs a few quid extra.

As for the co channel interference, i'm not even sure if thats the problem yet, if i can just improve the picture on the analogue channels and get a bit more strength on the digital muxes i'm already receiving i'll worry about it then if i can't get 29 and 33. I do believe if i improve my aerial it will improve the signal no end, i'm only using an 8 element quad at the minute, i'm sure a 20 odd element will make a lot of difference but we'll see!!

I live out in the sticks, there are sheds visible to one side of me but they're a few miles away and its very doubtful they would have any bearing on my signal.

There is no herring bone effect, just a fuzzy picture and sometimes a slight ghosting on UTV but again its hard to pinpoint an exact cause for that when i don't have the proper aerial set up.

No point me talking much more about it until i improve the aerial set up i have and if anyone can pass on a link to a pic or sketch of the quad layout Watty was talking about i'd appreciate it, thanks.

championc

The shorter the aerial, the wider the angle of view from it. So long aerials are far more directional and less likely to pick up stray signal coming from the sides.

The only thing I can find referencing CH24 is RTE2 from Magheroarty in Donegal with a 1kw.


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watty

championc wrote: »

Hi Watty

What brand and model aerials did you use ? I assume the baluns you refer to are the combiners ?

It was a well known UK brand. Blake. The Aerial's dipole is actually "balanced". The coax connection point should have the "balun" built in. The combiners (splitters in reverse) are not related to baluns.

https://www.blake-uk.com//page/Aerial_SR
SR18A, SR18B, or SR18CD

For stacked Quad Yagi arrays See
http://www.directivesystems.com/222MHZ.htm
http://www.antennaexperts.in/product-detail.asp?cat=quad-stacked-yagi-antenna&id=29


Stacking four Yagis gives 6dB more gain.

Each SR18A or SR18B has 13 dBd (about 15.7dBi) gain. (2dB better than a wideband version). So four gives 19dBd and about 1/2 the width of beam, 7 degrees instead of 14.

The Triax 100 is about 17dBd and 11 degrees and VERY MUCH LESS robust for ice/snow. It's gain drops more when wet. Including carriage the 4x SR18 should be about 1/4 to 1/2 the price. The three combiners / splitters are very cheap (get them and mast amp from Blake too).

No professional systems use yagis as high gain as the Triax100 or similar. They stack 13dBd aerials, it's about the point of best gain for you money and size with yagis.

Next up would be an array of 8 aerials, gives another 3dB! After that a very large mesh dish and single small yagi is better.

tvman

If you are going to such great trouble to get Freeview should you not be using a group K aerial to pull in all available muxs at maximum strength, both now and when the Divis tx erp is increased (by up to 35 times) when the digital switchover takes place.
Also any chance you are receiving signals from Killowen Mountain which relays Divis on the same channels (to feed Kilkeel Relay)

lawhec

From looking at this thread there's a few things worth noticing...

Your current reception of TV3 & TG4 on E59 and E62 is from Kippure, not Three Rock, and Cooley would be within the service area of Kippure whereas it isn't for Three Rock.

RTÉ1 and RTÉ2 on E29 and E33 would be highly unlikely to be causing cross modulation problems at such a distance from Three Rock for reception of BBC1 and BBC2 from Divis, especially two UHF channels apart and can almost certainly be discounted.

A possible reason for Channel 4 and UTV coming in better than the BBC channels on analogue could be down to a lack of line-of-sight visibility to Divis. The signal will be taking a path through the Mournes which can cause different effects. One is the screening and path loss of higher frequency signals, this might not seem so apparent but over a tricky terrain it may be a factor. Secondly the signal from Divis may be bouncing off the terrain along the signal path which at the end may see several different signals combine - if these signals are largely within phase (within 90 degrees with each other) then they can increase the wanted signal although there also might be ghosting, if they arrive at various different phases they can subtract from each other giving an appearance of a weaker signal and a snowy picture.

The problem receiving Muxes 1 and 2 from Divis will not be solved by a notch filter on these frequencies. It may already be the case that if there was no interference from Three Rock, the received signal from Divis for these multiplexes might be strong enough, but it does not take a high amount of interference from an analogue signal to disrupt a DTT Multiplex on the same frequency - one that would normally be considered far far too weak to be an acceptable signal going into the DXing range is enough to kill a DTT signal on the same frequency especially in fringe areas like your. In this case the first thing to look for is to reduce the interference from Three Rock, then once this has been achieved try getting a better signal from Divis again, though a small amplification after interference reduction may do the trick.

To do this requires at least two aerials and a special combiner for the job (it may be possible to use a standard splitter, but these have higher signal losses than what is usually liked) similar to what Watty has already described. In this case the trick would be for one of the aerials to be set up (or two in a four-aerial setup) so that when pointing towards Divis the combined signal from the two aerials are as close to being in phase as possible as this will give up to a doubling of the wanted signal (or at least each signal is less than 90 degrees in phase) while the unwanted signal from Three Rock reaches the combiner as close to 180 degrees out of phase as possible. Basic physics dictate that a radiowave being received 180 degrees out of phase to the wanted one when added together will result in zero signal. This way you can kill the signal coming southwards from Three Rock, while maintaining or even improving the signal from Divis.

It may not be possible to completely eliminate the interference from Three Rock, indeed it will be impossible to completely cancel out both offending transmissions from Three Rock (E29 and E33) as both channels cannot be 180 degrees out of phase at the same receiving set up at the same time (at least without some major complex setups) as well as the possibility of the signal bouncing off tall objects nearby reflecting back on to the aerial setup, however with some patience a notable reduction should be apparent. It's a skill in aerial installation that is lost on most nowadays, it was more common in the 1950's to 1970's more for signal gain than anything else really as two cheaper modest aerials could be combined together to give better results than a larger aerial that cost a lot more on its own. Having been in Australia for much of last year and coming back home last month, many phased aerial installations are still in place over there either to improve on weak signals (especially in rural areas) or to fight ghosting. The only domestic aerial installations these days in Ireland or Britain that I see these days using any phasing system is through the use of UHF Fireguard or Colour King aerials, which have phasing built into them as standard.

Without trying to use phasing to kill as much of the signal from Three Rock as you can, your best bet is to try and find a location which screens you from Three Rock but still provides acceptable signals from Divis. Ironically this may involve lowering the aerial closer to the ground, it will be basic trial and error.

Finally, as mentioned above me, to have a chance in receiving all six multiplexes from Divis at your fringe location, you will need a Group K aerial to receive Multiplex C on channel E48. A Group A has little chance of receiving that outside of Belfast.

Finne1993

tvman wrote: »

If you are going to such great trouble to get Freeview should you not be using a group K aerial to pull in all available muxs at maximum strength, both now and when the Divis tx erp is increased (by up to 35 times) when the digital switchover takes place.
Also any chance you are receiving signals from Killowen Mountain which relays Divis on the same channels (to feed Kilkeel Relay)

I'm only experimenting at the minute with old aerials i have around the house, i was surprised i even got any signal to begin with and thats why i started this thread to find out which is the best set up is for freeview, i picked up mux C no problem with a crappy group B contract aerial so i knew i would have no problem picking that up with a K or wideband aerial and wanted to see if the rest could be picked up on a group A that i had before i invest in new aerial(s) (I don't have any K aerials at home)
Is the signal going to increase by that much? sounds a bit extreme but great if it does.
And i'm definitely not picking up Killowen Mountain, its sole purpose really is to feed Kilkeel and is not pointed anywhere near where i am and does'nt carry a digital signal, i investigated all that on another thread. Thanks for your input, everyone has been so helpful, its really appreciated.

Finne1993

lawhec wrote: »

From looking at this thread there's a few things worth noticing...

Your current reception of TV3 & TG4 on E59 and E62 is from Kippure, not Three Rock, and Cooley would be within the service area of Kippure whereas it isn't for Three Rock.

RTÉ1 and RTÉ2 on E29 and E33 would be highly unlikely to be causing cross modulation problems at such a distance from Three Rock for reception of BBC1 and BBC2 from Divis, especially two UHF channels apart and can almost certainly be discounted.

Thanks for the very detailed reply, i've taken all you've said onboard and i'm gonna invest a bit more time and money in getting the proper equipment and signal, unfortunately i probably wont get looking at it this week as i'm very busy, hopefully the following week.
I did'nt know thats where the signal for TV3/TG4 was coming from, its an awful lot stronger than Three Rock anyway, i'm getting a perfect crystal clear picture on them channels and also picking up a 100% DTT signal from three rock on the same cheap C/D aerial in my attic.
I'll post more when i get properly set up, thanks so much for the reply, its given me a lot to think about, i'm sure i'll have no problem picking up all the muxes now

Galway

According to What Satellite March 2009 the power at Divis is going to increase by more than 40 times the current ERP on the digital muxes.

martin12

I would highly recommend the Televes Dat 75 they work very well in South East they will pull in signal from Wales better than any other I've tried here is a picture of one

lucernarian

The PSB muxes will be broadcast at 100kW from Divis. COM muxes will have 50kW ERP. This is according to the reference offer as compiled by Arquiva.

So yeah, up to about 40x the power (16-17db gain on existing levels, or better considering the frequencies used will have slightly better propagation).

watty

Actually I had helical filters for each channel (factory tuned by Polytron)and three sets of dual arrays of 18 element yagi aerials, A, B and C/D as the channelised aerials pick up less of other signals and have about 2dB more gain in the end. If you look at the K it's not truely wide band, peaks at C and drops of toward D and A, but more gently than C/D

The C/D also is a good bit better on C than D

Perfect analogue and Digital from Divis, but very poor from the Blackmountain.

Antenna

lawhec wrote: »

as well as the possibility of the signal bouncing off tall objects nearby reflecting back on to the aerial setup,

Also a rocky mountain-side in the distance to the front of the aerial could also cause significant reflection of the unwanted co-channel signals from 3rock.

Galway

DAT 75 not recommended for any gr A channels - gain is no where near the claimed 19 db there, better with groupised stack.

watty

I think those triple boom aerials are over-rated and poor value. The more robust "Blake "18 element is dramatically better build quality and very much cheaper. If not enough gain stacking two is still cheaper.

martin12

http://www.cai.org.uk/downloads/CAI%20Aerial%20Benchmarking%20Scheme.pdf

lawhec

martin12 wrote: »

http://www.cai.org.uk/downloads/CAI%20Aerial%20Benchmarking%20Scheme.pdf

What the CAI benchmarking system doesn't show is that the gain of the DAT75 isn't flat across the band, but its peak, like all "wideband" yagis, lies around the E50-E60 channels. In the Group A UHF channels, especially the lower frequencies, the gain is roughly the same of a good 18 element Group A Yagi. For receiving a transmitter which only transmits between 470-610MHz, a DAT75 will not be the best solution, especially considering the weight and wind load. For receiving from a transmitter whose channels fall into Group B, C/D or does truely cover the band, the DAT75 does come into its element better.

Quite simply wideband yagis, which are always a design compromise, shouldn't be used for the best performance of receiving signals from a Group A only transmitter.

A few years ago I purchased a Blake DMX10A for use in our attic to receive analogue and digital signals from Brougher Mountain into a bedroom directly below it. It was designed for DTT use only really, it got 5 out of the 6 multiplexes and with the use of a setback amplifier (I'd not normally recommend but I had a spare one lying around and did the trick this time) brought in the sixth. Regular readers of my posts will know that I live halfway up the wrong side of a hill which lies between me and Brougher Mountain approx 10 miles away. A local aerial installer, who thought that I was taking the piss couldn't believe it worked even with 5/6 unamplified or 6/6 amplified. He now stocks a few of them in locations where the signal from Brougher is weak and the customer is demanding Freeview. The house was rewired up, including TV cables while I was in Oz last year. DTT is strong enough now from the communal setup so the aerial for the attic hasn't been reassembled and is lying in the secondary attic above the shower room in pieces waiting to return to action at some point!

Watty, in some cases you are right, it is preferable to install different grouped aerials rather than go for semi-wideband aerials like E or K. E48 from Divis though does kick people in the nuts trying to receive all multiplexes along with RTÉ from Clermont Carn as the majority of pre-DTT or even Channel 5 setups likely had a Group A/Group E combiner. A proper install these days for such system requires one input to take in E21-E49 and the other from E51 to E68. I think Triax made such grouped combiners back at the start of the decade.

Finne1993

Changing the subject slightly away from my problem with Divis here, I still never got doing any more experimenting with my set up yet, i will in the next week or two hopefully.
I was in three different houses in Dundalk this week who reported problems with their analogue signals, serious interference running through all the channels, looked like too much power and i attenuated the output from the masthead amp power supply and it sorted all 8 stations out except BBC1, no matter what i done with it the interference was running through it as if there was a radio interference, have they boosted the signal from Divis or has something else started broadcasting around the same channel, very strange that the very same thing happened in three houses. before this their signal was perfect. Their digital signals are still fine by the way. Anyone any suggestions or possible expanations?