Antenna question 2 anomalies

[Tasman]

I did not want to interupt the first question, but it raised some thoughts. Years ago in the analogue days, we had a Digimatch DY08? Band 2-12 and a Gamma 20 UHF aerial. MHA was a GME MHW38. At the aerial, my old analogue meter (half the size of a suitcace) would give a reading for 62.25/175.25 and 548.25 but practically nothing for 527.25. The RG6 cable ran down the fence line for approx 150m. At the bottom, SBS was AOK. Could it have been induction from the fence line that gave us the picture?
In a sea of antennas along a (different) fence line, is there a possibility that one aerial placed in front of another, say 10m apart could impact on the other?
Thanks.

[trash]

... is there a possibility that one aerial placed in front of another, say 10m apart could impact on the other?
Thanks.

No, not unless it's as big as it is distant. For example, if the Parkes telescope were 10m away.

Could it have been induction from the fence line that gave us the picture?

No.. well generally no. It require a few things to be wrong, not just one.

The RG6 cable ran down the fence line for approx 150m.

Oh, I think we have a winner !

150m of cable is a long run in my books for normal VHF/UHF TV.
It requires some special consideration. The first is how much signal is arriving at the cable from the antenna.
First is the loss of the run. For RG6, it's not going to be good. It would not be any better for RG59, but generally it is a better for insertion loss.
RG11 is much more suited to this kind of run.

The big concern is the frequency response combined with the return loss of the cable. Normally I'd just check it with a sweep generator. It can be done with a signal source and an SWR meter or even a power meter, but you'd have to take a measurement about ever 3MHz to get some sort of idea.

What is the fence ? Is it just a wooden stock fence in a paddock or a suburban colourbond etc ?

[gordon_s1942]

Trash, I am going to partly disagree with your 'co-acting' antenna reply as I and a friend each had a Hills CA-16 phased array antenna mounted side by side some 45 feet high using a Pine Tree as the mast, both had MHA's due to our very poor reception here and we both noticed a 'degrading' of the signal when he took his antenna down for some repairs and put it back in a different position.
Both were fed with 300 ohm tape but both did not run paralel to each other.
When towns had literal forrests of high masted multiple arrays, MHA's etc there were occassions when it was found that some interaction did occur.
I read of a place in the US putting up an old metal sheeted Billboard on a hill above a town and they placed it to reflect the VHF signal down into the town.
Large metal oblects such as tanks were notorious causes of ghosting.
As we spoke of earlier, the transmission line CAN become part of the antenna system which depending on whether it aids or detracts the signal quality as to it being a problem or not.
I am not an installer nor a technician but learnt most from a Serviceman who lived and worked firstly doing Radio then TV as it was introduced in a country town surrounded by high hills some 80 miles from Sydney and how they worked using all sorts of Antennas and mast heights to drag in the tinniest particle of signal from the far away transmitters.
Nothing he did was outside the accepted theory of Radio/propogation but with the varying combinations prevailing, sometimes you could get a totaly different result to what you would have expected.

[trash]

[quote=gordon_s1942;388591]Trash, I am going to partly disagree with your 'co-acting' antenna reply .....
.... Large metal oblects such as tanks were notorious causes of ghosting.[quote]
Ah, ok. I was trying to work out what you were referring to. But ghosting and reflections are different to errr.. "co-acting".
The correct description would be something in the "near field" of the antenna.
Ghosting does reflect the signal causing a multipath signal. But this isn't the same thing. In the case of say your neighbour's antenna being exactly between your antenna and the transmitter, their is a 'shaddow' so to speak but it does not extend much more than a couple of wavelengths behind.
At VHF and UHF, this is only several metres.

I read of a place in the US putting up an old metal sheeted Billboard on a hill above a town and they placed it to reflect the VHF signal down into the town.

Yes I have done this myself to give mobile phone coverage in a location which did not have it. It was a last ditch effort because there was no official reason to extend the coverage into this tiny pocket of terrain.
It increased a GSM signal from below -101dB up to -96dBm.
It wasn't enough to hold a phone call, but it was enough to get an SMS through. The reflector was four pieces of sheet metal placed on the hill with star pickets and poles.

If you go to Smiggin's holes, you will see similar reflectors used for microwave links. They of course work much better at higher frequencies.

As we spoke of earlier, the transmission line CAN become part of the antenna system which depending on whether it aids or detracts the signal quality as to it being a problem or not.

Of course, which is why I'm not touching it at HF in porkop's case

In the case of RG6 ....<moan> more information is required.
In this case, more info about the fence. At least to start with.

[Tasman]

Wow guys. What have I started - way beyond me already.
Fence is a typical 5 strand wire with wooden posts This is the Bush!
Know a farmer who was pissed off that his neighbour had TV reception, so he ran a cable 'half a mile' up the hill and set up an aerial on top - old analogue days. No MHA as I recall. "Perfect picture, boy, perfect picture"
Assuming RG6 attenuation of 6dB for ABC, 10dB for WIN and 16dB for SX and SBS/100metres of cable. 150m would = loss of 9, 15 and 24dB approximately. Well within the MHA's capability to deliver sufficient signal to the set assuming we get a pure enough, even if weak signal. Have not read an analogue signal in yonks, but I would think 42 would be superb but more usually in the 30's. This is a Zone 2 area but there occasional pockets of joy to this installer.
I frequently got "You can't put the aerial there. You will block my neighbour's signal' Hence the question. Now I can confirm that it is OK. Thanks.

[gordon_s1942]

Tasman, when I moved here in 1963, I had come from an area on the upper Blue Mtns (Katoomba,66 miles West of Sydney)) where at some places you chucked a bundle of ribbon tape 'Out the Wndow' and got 'perfect' reception but move around the corner and get Zilch.Some even claimed to attach the lead to the wire of a 'Fly Screen door' and got a signal.
I have seen 27 inch bycycle wheels connected together that the user claimed worked.
27 inches is either the 'Quarter or Half Wave' of the VHF TV signal, cant remember, old farts desease.
Here now about 90 miles and further west in a shallow valley, the reception was bloody woefull.
A typical country town All Purpose Retailer had an 'Appliance/Radio/TV' service man and he would sell and install TV's and antenna's so he did the 'Hard Yards' and being a 'Local' knew the area well.
It was he I found as I tried to get any sort of TV signal where I am and he had installed numerous remote antennas up the sides of the surrounding valley walls such as your Farmer had done.
He rightly said the Village was almost a total 'Dead Spot'.
At one time I put up a single Phased array to try and get a signal from Orange, 80 miles away to the west (ABN1 and CBN8, Vertical but I had to face the antenna SOUTH, not West and for one channel, I had to turn it to the Horizontal.
Obviously I was getting a 'Bounce' from a hill.
Tasman, what you describe your Farmer as doing was done around the Town of Lithgow with at least 30 antennas I know of. In one area the street all chipped in and actualy installed an antenna above a dozen or so houses and with 'Open Line' connected them to this antenna.
That by the way was Illegal under the bloody idiotic Radio and Broadcasting Acts.
All gone now because of the installation of translator covering them now.
Remember too that the TV's were all valves and not as 'stable' as they are now with weak weird signals, funny things did happen.
For years I had a problem with ABC2 Sydney being interferred with by RVN2 Wagga (Commerial) 200 miles away and that was comming in at 90 degrees to my antenna.
For several days one Summer I had a confirmed Signal report of receiving TVT2 Hobart Tasmania varying from Picture/Audio interchanging to a solid viewable and listenable reception from the Tasmanian transmitter.
The films being run were 'Fireman Save My Child' with Spike Jones and the other was the life story of Mozart, two totaly disimilar films you could possibly find.
Finaly, our antennas were side by sde, each on a short mast on each side of a pine tree that provided the main support.
The tips of each element were probably 4 to 8 inches apart so what we had done unknowningly was basicaly 'phasing' them together and apparently this worked in our favour.
Lots of things were done by those like me who didnt have a clue and sometimes we struck lucky, not often but sometimes.
The 2 of us walked all around the Vilage with a 20 foot mast, antenna, 12V B&W portable TV and tried spots some 50 feet apart as we went.
Years later I again tried with a UHF Yagi, 12V MHA, 10 foot mast and TV and FSM I had been lent (I really didnt know how to use it) looking for 'Sweet Spots' but that was pre Digital signal days.
Now I read there is a 'Possibility' of a transmitter being installed 'Locally' around one area I favoured so if it does eventuate, I am going to write on the wall, 'SEE? I said put it HERE'.
And to put it bluntly, we tried because we had no other choice because the alternative was no TV at all.

[trash]

I frequently got "You can't put the aerial there. You will block my neighbour's signal' Hence the question. Now I can confirm that it is OK. Thanks.

yep. I had one old guy complain that 3G was "sucking the signal out of CDMA" when they were both running. When I demonstrated that both were ok from his front veranda by calling one from the other, it was then a conspiracy.
Which also explained why his TV pictures were worse since 3G.

[Tasman]

Hi. Perhaps we should remove this thread to the jokes thread! Nothing fits! I am on my daughter's lap-top computer and the keys don't work the same way as I am used to. What is Fn . Can not find q4est56n 0ar2. See you Tuesday.

[gordon_s1942]

One thing I was told which I thought was abit far fetched but later had proven big time was problems caused by MHA's radiating.
These twin brothers fiddled with all sorts of hobbies and one was TV and they told me of an instance where an MHA was causing heavy interference to this persons neighbours TV's in this close cluster of houses.
The houses were what we called 'Duration Houses' built during WW2 for factory workers on 1/8 acre blocks and as such were very close and this MHA was on a pair of Phased Arrays on a 40 foot mast as was everyone elses.
The MHA radiated this interference for some 500 feet I gather.
Many many years later, I noticed I was getting really bad interference on a channel (10 Sydney I think it was) but it came and went erractically but mostly after 6pm to 9pm period.
I had bought a radio that covered AM/FM and all the TV band audio so I decided to do a bit of 'Sniffing' and when the 'noise' started, I went for a walk around the village and I found the interference was comming from one house.
One of the house holders family was living in a caravan and they had put an MHA onto an antenna there and this was the problem.
Whatever was wrong with their installation effected one of their channels as well.
We eventualy came to an 'amicable' arrangement that when they werent watching TV, they would turn off the power to the TV/MHA.
Fortunately they moved a few weeks later and took the rotten MHA with them.

[gordon_s1942]

yep. I had one old guy complain that 3G was "sucking the signal out of CDMA" when they were both running. When I demonstrated that both were ok from his front veranda by calling one from the other, it was then a conspiracy.
Which also explained why his TV pictures were worse since 3G.

Been there and done that with a woman who claimed my MHA was interferring with her TV even when the antenna was taken down and the MHA was put back in its box and shown to her that it was not connected.
She had got an inheritance and paid out 700 Pounds (1964) for a new TV and antenna/mast but no MHA and could barely watch ONE channel so the desperate installer who was copping heaps from her, looked around and saw my antenna accross the road and blamed it so I copped it then.
All these years later the FTA TV reception is still no better.
After that I put my antenna back up with MHA attached and told her very politely (I was only 21 then) to 'Go Away'.
This I might add was long before I heard the story and experienced that problem myself but even so, unplugged and packed away with the antenna on the ground dont work for me !!

[trash]

ah, you know people like that are just magnet for me

I would find the temptation to remove that last channel waaay too tempting as well as erasing the entire AM broadcast band. Of course that would only be the beginning of much worse psychological warfare. Eventually when the subject has returned to her gelatinous form, then basic behaviour modification can begin to turn her back into a nice person. Eventually nice people will want to help her and before she knows it there will be 15 or so crystal clear digital channels for her selection.
Lucky that the programming has not changed on those channels in 40 years, so she'll be able to see the next episode of "I love Lucy" right where she left off.

[gordon_s1942]

ah, you know people like that are just magnet for me

I would find the temptation to remove that last channel waaay too tempting as well as erasing the entire AM broadcast band.

How I proved to the Caravan dweller their instalation was 'noisy' was to stand in front of their TV with that radio I had and they turned off the power,off went the noise. Power ON and the noise returned.
The chap was a bit of a loud mouth and still wasnt convinced untill I tuned the radio to find the 'mix' of the signal and wiped his TV screen.
He still was huffing and puffing and blustering saying he had bought it and installed it and he wasnt going to etc,etc,etc, so I just fine tuned the radio dial (analog tuner) and totaly took out the picture with heavy herringbone and buzzing noise.
I intimated to him it wasnt hard to set up such a devise outside the boundry line facing the antenna and have it running all the time (I didnt have a clue how to make one) and he would have no TV at all and as we were not in a TV coverage area, there was nothing he could do about it.
Thats when we came to the 'Turn Off when not in use arrangement'.

[trash]

You waaay to tollerant of these people's bad behaviour.

Good people I go out of my way to help. It's no skin of my nose to help them and I know that a little bit of help can make a big difference.

On the other end of the spectrum, catching a monkey never ceases to amuse me.

[gordon_s1942]

Trash, when you live in a small village it doesnt always pay to be too beligerant and as I said I couldnt complain about his faulty/badly installed equipment because we're not in 'Deemed Reception Area' and what TV we got was classed as 'Fortuitous'.
Although I knew that it was possible to 'Jam' signals, I didnt know how to make a jammer and there was always the possibilty it could have affected me too, not a good idea.
I learnt from it, both how to find the problem and a solution to it.

[Tasman]

Quote- 'when you live in a small village'. Someone recently 'borrowed' the distributon amplifier, which left about 20 people without TV reception - including themselves!. Then someone ripped the splitters and taps off the cables. Now everyone wants to install their own aerials in a very poor reception area. The old system had been erected in one of those beautiful little hot spots (and it is an old VHF/UHF antenna) and yet just 10m away the signal strength decays and if I get a MER of 20 I'm lucky. Yet they want what they had previously received and I am the bad guy for not being able to supply and yet have the cheek to charge! My Hills Fast meter usually shows a poorer reading than the Sefram 7803. What is your opinion of STB's that seem more capable of giving a picture when others fail on some if not all channels?

[gordon_s1942]

To misquote that old engine oil TV advert 'Tuners aint all equal, Tasman'.
I had a Samsung VCR bought new,had the tuner replaced and it still wasnt as good as an identical model a friend had.
The theft of the master MHA is what happened in the town I mentioned earlier to some of the individual instalations along with an occasional lightning strike killing the MHA's which to me today barely makes it worthwhile trying to run such systems.
If enough people are interested in putting up a 'community system' then why not try for a translator to cover the area?
It wont be easy but it has to be the better option.

[Tasman]

Hi Gordon. By translator do you mean a Band 111 digital to presumably UHF Band V converter and transmitter. The location for this would be on a mountain top with no road access! Or did you have some other scheme in mind?
Had a great day today. Whilst balancing a 2m pole with a DY14 atop, sitting this on a fence post with one hand and twiddling the meter's knob with the other, I got 4 passes and one marginal. A 'first'!