dumb TV antenna question

[bennylaird]

The Horizontal and vertical you mention is the polarisation of the signal. A radio wave has an electric field and a magnetic field. These are separted by 90 degrees along the line of propagation. Lost yet? They tend to use different polarisation between areas just to cancel out itterference from distant transmitters.

All you need to do is look at everyone elses and make sure it is the same. Sure it will be and as you can get some signal with a pair of wabbit ears then there must be lots of signal around.

You may be able to get a good reception purly by bypassing the amp. Just make up a short lead to connect the antenna to the feed past the amp and see what it's like.

[knucklehead]

Trav, becarefull that the box on the antenna is an masthead amp. Many antennas have a balin in this spot.

If this is the case it probably has a connection between the co-ax cable and some ribbon cable going to the antenna elements. If it is just a balin have a look inside. It may have obvious signs of damage or water ingress.

In short look of the simple stuff first. Many guys will sell you a new antenna and amp to fix it only to find the problem is a $2 connector.

[Tankstand]

Trav,

You can't just plug in a STB (Correct me if I'm wrong here folks!). They also need a reasonable signal. I have always had dodgy reception on Ch2, I bought a STB and it couldn't tune in Ch2 either because (as it told me )the signal strength was less than 50%! (Took that sucker right back!)

Thank heavens for Foxtel Digital!

Crystal clear Ch2 and SBS! (Unless there is a storm somewhere!)

[Clinton1]

bennys talking my language! !!

[doug1]

Trav

You need to be a little carefull with the ampliier, depending on its model number and maker it may need different types of power supply, they are not universal

get a model number off it first if you can , then can probably find the power supply you should have attached to it.

They usually plug in behind the tv to the coax and send power back up the coax.

If you had good reception a couple of streets away it shold be reasonably easy to fix this one if the antenna is suitable for where you are

Doug

[bennylaird]

A masthead amp will only amplify the signal the antenna can pick up so it's not a miracle worker. Be sure your antenna is suited to the channels you want to pick up. Channel 2 is in the lower range and needs the longer antenna elements whereas SBS is higher and requires the shorter elements. You can buy a high gain antenna that cover the full band or separate antennae. Also the transmitters are not all on the same mountain so you can improve reception by using multiply antenne each aimed in the right direction, usually and overkill. Other problems are valleys and large trees. Trees make great antenna and shield your signal. Signal that passes and is reflected back to you causes ghosting, two pics side by side on the same screen.

Best advice is spend a little and get an installer to set it up. He will know the area and have a signal meter if he is any good and will set you right for years to come.

Next step is to start playing in the roof with distribution amps and splitters etc to get the whole house wired with Foxtel and HD TV to every set, a second Foxtel bos is only $20 a month extra and worth it when you have a few kids in the house. Only trouble is:

Turn off the Bl--dy TV and get out to the shed and enjoy your woodwork instead!!!!!!

[Trav]

Thanks all - esp Benny. Good advice.

I wandered into Dick Smith's today and had a look at their aerial setups etc. I actually spotted the booster that I have - it is a kingray - and noticed that it had a power supply exactly as you pictured Benny. As that power supply is nowhere to be found, I may need another one.

I ahve also learned that the coax cable has a join in it - conveniently placed which is good. I am thinking it may be easier to replace all the coax wire - it only seems to be a few $ per metre.

I will also have a look and check the condition of all the other connections etc.

Hopefully I will be able to report back on Monday. It is, however, meant to rain this weekend again. Wonderful. Great moving weather.

Cheers

Trav

[Iain]

Kingray amps work on a multitude of voltages dependant upon the model, Set top boxes do not necesarily require high signal, depends upon the quality of the unit, mine is an Emtech and works as low as 30db microvolt, normal TV will start to fall off at about 50dbmv.
A balun is generally a smallish device in many forms and is usually within 150mm of the antenna.
If you wish to upgrade the antenna consider a log periodic which is 75ohm and does not require a balun=less to go wrong, more compact, higher gain.
Replace coax with at least RG6 dual shield but preferably quad use F type spli
tters if you want other points, twist on fittings are available from most TV outlets and do not require any special tools.
Kingray also have different powered amps from 10db to 40db, bigger is not always better and too much power to the front end can cause damage or similar results to lack of signal.
Amps like to be run at maximum output for optimum performance, not like your stereo which will distort at high levels, these are operational amps and work in a different manner.

[ChrisH]

The box on the antenna mast may not be an amplifier at all, Kingray also have diplexers which are a non-powered gadget to combine separate VHF and UHF antennas into one downlead to the TV.

However considering it sin't working properly, I'd guess it is an amp and needs a power supply.
Kingrays are almost all 22 volt AC but newer ones are 17 volt AC. I believe they all work OK with the 17 volt power pack.

go to Kingray's website for details of which models use which power supplies.

First just to check, bypass the amp by connecting the input to the output at the amp, if pic is good you may want to forget about the amp and just connect the cable direct to the antenna.

You really need to find out what channels are broadcast on UHF and VHF so you can decide if you have the antennas you need or not.

Chris

[Trav]

Thanks all.

I have done some more research that I thought I would share with people. I had to move house on the weekend, so I didn't get a chance to try and fix my reception problems, so this is all theory at the moment.

For anyone who is having reception problems, these two documents look pretty useful in identifying and resolving the problems.

http://www1.electusdistribution.com....d/tvrecepe.pdf

and

http://web.acma.gov.au/radcomm/publi...o/BTRbookl.pdf

I understand that my antenna is a UHF only antenna, but that I have a repeater station close (direct line-of-sight) by that transmits all the 5 main stations in UHF frequencies. But I am finding it really hard to work out what these frequencies are - or if this info is entirely correct.

The box on the amp is certainly a masthead amplifier, but there is no power supply, so it simply serves as an attenuator at the moment. Wonderful. I also have the crappest cable imaginable I suspect. However, much of the info on this subject suggests that these amps may be more trouble than help. I think I will disconnect it and see if I can improve the situation.

Can someone confirm the best type of coax cable in this situation? Is it RG6?

More info to come as I find it. I would appreciate any info on how to find the frequencies that all the stations are transmitted on in Canberra - Mt Taylor in particular.

Cheers

Trav
(reception noob)

[doug1]

This may help
source thread: http://www.dtvforum.info/index.php?showtopic=7806

Now for something coming from a non-antenna installer. For best results, it is good to have a proper UHF antenna and VHF antenna that is digital ready. It also is good to have high-quality cables (eg. RG6) BUT I have recieved digital TV (from Tuggeranong Hill (all UHF)) with a $15 DSE UHF/VHF Antenna.

So I suggest that you try to get another type of antenna (indoor or out but not the one you have (which sounds the same as mine). It's not good for VHF. Even simple rabbit ears would be better). One antenna that you could use for indoors is a Fracco (pardon the spelling). I think Gadget sells them (PM him).

Also, with a cheap indoor antenna, you have to do a lot of tweaking to get good reception. This involves moving the antenna around a lot and making sure the reception on each channel is good.

BTW. Signal Strength isn't the best indication of your reception. It's the actual quality that matters with Digital TV (eg. I have had 50-60% signal strength with around 80-90% quality (with a VisionPlus DVB-T)).

Just for reference, here is my signal strength/quality readings:
----------Black Mountain-----------
SC TEN VHF6 Strength: ~95%Quality: ~23db
ABC VHF9A Strength: ~78%Quality: ~19.1db
WIN and PRIME Not avalible due the VHF antenna being old (doesn't really matter. It picks up ABC from Black Mountain which is good when the ABC Tuggeranong Hill transmitter dies)
SBS UHF30 Strength: ~83%Quality: ~20.1db
----------Tuggeranong Hill-----------
SBS UHF57 Strength: ~90%Quality: ~22db
ABC UHF59 Strength: ~90%Quality: ~22db
SC TEN UHF62 Strength: ~77%Quality: ~18.7db
WIN UHF65 Strength: ~84%Quality: ~20.5db
PRIME UHF68 Strength: ~88%Quality: ~21.5db

All readings are from using a DVICO FusionHDTV Digital TV card, mostly RG5 cables. newish Hills UHF antenna and a old VHF antenna which is not digital ready. Readings are from the suburb of Fadden.

end copy

Doug

[Iain]

For best results, it is good to have a proper UHF antenna and VHF antenna that is digital ready.
Doug

That is one of my pet hates, what the hell is digital ready, just a left handed wank inspired by marketing gurus to sell what is no different to other antennas.
Either an antenna is cut for specific frequencies or it is not and to get someone to buy a new antenna 'for digital' is nothing short of a rip off.
Antennas are usually cut for specific bands being:
Band 2... channel 2-5
Band 3... Channel 6-12 (digital VHF starts at 6)
Band 4... Channel 24-34
Band 5... Channel 35-69
These are also available in combinations, eg 4-5 3-4-5 3-4 and as stated earlier a log periodic is a very compact antenna with an ectremely high gain, but will not go below channel 6, which for digital is not a problem.
As for signal strength on STB's when they read ??% signal strength, this is an extrtemely nebulous figure, eg: 60%, but 60% of what????
Ideally you need a signal strength meter for an accurate reading, or better still a spectrum anyliser to get the best signal with minimum distortion, but at about $3k not a viable option unless you know how to drive one or have the use for one.
And RG6 quad is about the best coax to use, cheaper from a TV repair shop than BUnnies and probably better quality, and if using splitters go for 'F' types, wall plates make sure thay are not the isolated variety if using an amp as they won't work.
Doug, those db figures are way too low for operating any TV system, ideally for TV the optimum strength is 75db, below 50db things start going snowy, my STB will work at 30db but will freeze and pixellate and that is one of the better ones.
I don't really know what those figures are indicating :confused:

[reybec]

i don't know about foxtel but when we had optus tv connected we were getting absolute crap picture from the antenna (a palm frond had fallen down & broken it) beforehand.

after optus was connected the reception on all channels even the free to air was perfect using the same antenna because it run through a cable apparently.

[Iain]

Pretty sure Optus run free to air as part of the service.

[Trav]

Foxtel only provide SBS and ABC free to air channels in Canberra at the moment. I think some of the other states get nine as well. But not in Canberra. I wish that they would hurry up and get the other free to air channels - it would stop me having to fiddle around with the antenna etc.

TRav