How do I correctly align aerial?

Lochlannach

Ok short of buying a signal meter what is the best way to align an aerial (which will probably be strapped to the chimney rather than being in front of the tv)? I'm in Kildare town and will be aiming for the Kippure transmitter - this I know from the maps is roughtly east of my location. So how do I get the alignment right? Any and all tips are welcome - I don't want to spend too long on the roof - well once it clears up enough for me to get up there in the first place .

Tom Slick

I'll assume you're looking for Saorview transmissions.
I suppose the best you can do is get someone to keep an eye on the tv & either use its signal strength/quality display (if it has one) or an analogue channel for reference, and relay this info to you on the roof.

cauliflower69

left abit, right, you had it it. Back abit

John mac

use a compass,


if you have a i gadget thingy or android, there is one built in.

if you haven't got a map you can use google earth.

jamescc

get an aerial meter from maplins only cost about 30 euro or so

Tom Slick

jamescc wrote: »

get an aerial meter from maplins only cost about 30 euro or so

Probably more than the aerial cost . . .

Use a compass for a rough idea, then "peak it up" using the tv itself (and a helpful assistant). Signal quality won't be displayed by these cheap meters, so you don't gain much advantage for the extra outlay.

The location of the aerial is just as important. Alignment won't count for much if it's just pointing at a building, trees or other obstruction.

watty

Unless it's a monstrous big array, you don't have to be that accurate, vertical or horizontal is more important.

Accuracy required is about x20 to x50 less than a satellite dish

Sponge Bob

Vertical/Horizontal explained here with pictures, you would strap a pole to the chimney and witha spanner attach the aerial to the pole with clamps...but I would try inside the attic first

http://www.rtenl.ie/downloads/new-Receiving-Saorview-DTT-October-2010.pdf

12 element

A compass is probably your best bet, If your getting someone to help you don't forget being too close to the aerial can affect the signals so make sure your not too close to it! What kind of aerial is? The more elements the aerial has the more directive it is.

winston_1

Sponge Bob wrote: »

Vertical/Horizontal explained here with pictures, you would strap a pole to the chimney and witha spanner attach the aerial to the pole with clamps...but I would try inside the attic first

http://www.rtenl.ie/downloads/new-Receiving-Saorview-DTT-October-2010.pdf

That diagram for fitting a coax plug is completely wrong. The braid should be brought outside the claws not bunched underneath where it won't make proper contact. The centre core should be soldered. Just kinking the wire is not good enough.

watty

Not many people have soldering irons. A kink is better than nothing.
Some designs of plugs the briad is compressed under the claw.

The basic issue is that a "belling lee" plug as used by TV is a poor design for UHF. It was for 50MHz. Not 500MHz to 870MHz.

Lochlannach

Well the aerial is a 18 element wideband. I have made an attempt to set this up in the attic but I received a poor analog signal at the time through compass aiming (very slightly north of east). I think the fact that the roof is tiled and there are a line of houses at the back which are slightly higher than ours means that I'll need to put it on a pole on the chimney in order to succeed. I'd prefer to have it in the attic or on the gable as it would make mounting it easier (no need to have to get a roof ladder from somewhere). I should also mention that was just the aerial with no amp which is something I don't know if I'll ultimately need.

One quick question on wall plates...
At the moment I have the cable from the attic terminating in one of those TV & FM wallplates. However I want 2 feeds to the HTPC (recording and watching) and I believe these wallplates are basically useless in this case. Can I use the satellite types (i.e. 2 "F" connectors) or do they block frequencies?

Tom Slick

Can you receive Mt. Leinster in your area? It would be slightly east of south, about 35 miles away, with no major obstructions.
Channel 45 AFAIK, not sure if it broadcasts full power in your direction.
Also horizontal polarity.

watty

Wall plates are often rubbish and copies of Band I VHF 1950s designs

F-Connectors work DC, 22kHz, 0.1MHz to 3GHz (3000MHz).

Splitter/Combiners for F-Connector arr 3 main families

• TV Splitters work 5MHz to 870MHz
• SAT/TV Diplexers "split"/"combine" at about 900MHz. One connection is common DC to 2.5GHz. one is TV 5MHz to 870MHz and the other is DC, 22kHz and 950MHz to 2100Mhz approx for satellite box or LNB.
• Sat Splitters work 900Mhz to 2500MHz approx. Only for special Quattro LNBs or specialist Distrubution systems.

Splitters work also as Combiners.

There are also "unmatched" splitters for distribution "trunks". One leg is 1 to 2dB loss and the other leg is maybe 7dB to 11dB loss. The low loss port/leg "daisy chains" to next splitter and the higher loss port/leg to the local box. These come in TV or Satellite flavours.

You can't split Normal satellite signals, like cable to a Sky or Freesat box.

Lochlannach

@Watty:

I'm not going to be doing any combining/splitting for this installation.

I've got two runs of coax from the dish already in and working (twin "F" connector wallplate by the TV). I've additionally installed a further two runs of coax from the attic (not fun to do but I got it done) to the TV/FM wall plate that I had lying around. I just need some sort of wall plate there rather than a hole in the wall and was wondering about the use of these - I think my best bet based on your post would be to swap this for a "F" type plate as it doesn't exclude the frequencies that the standard TV signals are transmitted on.


@Tom Slick:

I hadn't considered Mt. Leinster as I thought that Kippure was the closest but I'll certainly give it a go - I'll need to weigh up whether my neighbours are in the way as the house faces east/west ish.

I don't really care where I get the signal from as long as it's ok for DTT.

Tom Slick

Lochlannach wrote: »

:. . . to the TV/FM wall plate that I had lying around. I just need some sort of wall plate there rather than a hole in the wall

You could remove the inner part of the wallplate and simply pass the cables through the holes.

12 element

Lochlannach wrote: »

@Watty:

I'm not going to be doing any combining/splitting for this installation.

I've got two runs of coax from the dish already in and working (twin "F" connector wallplate by the TV). I've additionally installed a further two runs of coax from the attic (not fun to do but I got it done) to the TV/FM wall plate that I had lying around. I just need some sort of wall plate there rather than a hole in the wall and was wondering about the use of these - I think my best bet based on your post would be to swap this for a "F" type plate as it doesn't exclude the frequencies that the standard TV signals are transmitted on.

DTT.

The best thing to do is just remove the circuitry from the back of the faceplace and run the coax straight through the plate and into the receiver. If you're only going to have them permanently connected anyway it's not going to look any worse.

The Cush

@ Lochlannach

"F" connector wall plates available from http://www.satcure.co.uk/accs/page15.htm#plates or make up your own.

FREETV

Lochlannach wrote: »

Ok short of buying a signal meter what is the best way to align an aerial (which will probably be strapped to the chimney rather than being in front of the tv)? I'm in Kildare town and will be aiming for the Kippure transmitter - this I know from the maps is roughtly east of my location. So how do I get the alignment right? Any and all tips are welcome - I don't want to spend too long on the roof - well once it clears up enough for me to get up there in the first place .

Well if you own a small idtv with an mpeg4 tuner or even mpeg2 that has a built in signal meter readings or an stb which shows the signal quality and signal strenght, you could use a pair of binoculars, small telescope with a cover over your equipment in case it starts to rain/snow again. For God sakes please keep one hand or better still both gripping the chimney or pole while turning your aerial and tweaking both levels to their highest signal strenghts or ask someone to ring your mobile and give you the readings or shout them up to you. Also try tilting your aerial upwards about an inch or a little more so as that decreases noise and raises the gain a little. I did the same with a Comag Silvercrest SL65 satellite receiver for two dish alignments for my Dad at his house, no extra meter needed just the binoculars as the tv used was a tiny 14" Philips crtv and it was difficult from a height to see the readings from its screen. It is easier to align an aerial as Watty said.

Lochlannach

Just an update in case it helps anyone else...

I decided to have another go on the attic installation based on another survey of my area and the transmission maps for Kippure. There just didn't seem to be that much that could block my signal...and I was right!!!

I brought the tv upstairs and used a length of cable direct from the aerial to it and bingo I was up and running with a good analog signal for tv3 & tg4 (the tv in question doesn't handle Saorview). As mentioned by Watty earlier alignment is very tolerant with aerials - I had a massive amount of movement before it would adversely affect the reception.

Anyway I then connected it up to my new cabling down to the sitting room and discovered there were problems. Turns out that the short lead between the wall plate and my htpc was only fit for the bin and also the original TV-FM wallplate was bad also. Once I eliminated these two elements from my system the htpc happily found all the Saorview content. Success without any need for ladders or additional mounting brackets

For anyone else in or around Kildare town I can confirm that Saorview is possible using an attic installed aerial.

watty

This is why I don't beleive in wall plates.

If folk insist i recommend a deep box and plate with F-connector barrel or Diplexer mounted in it.