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Digital TV Antennae upgrade

Hi All,

I'm in a difficult reception area here at Salisbury Heights in Adelaide. I have a ridgeline which shields me from the Mount Lofty TV transmitter antennas, and a 33KV trunk mains running across in front of my antenna complex.

I have a two antenna set-up which I installed in 1996. It consists of a VHF/UHF Tandy 18 element VHF/UHF antenna plus a 12-element UHF antenna which I bought from K-Mart (I don't remember the brand). The two aerials feed into a VHF/UHF Tandy masthead antenna amplifier. There are also indoor booster amplifiers on the 6 room distribution system. The antennae system supplies signal to multiple TV's, PVR's, VCR's, FM radios, & DAB+ radio.

UHF reception of SBS with the K-Mart UHF antenna is excellent, whereas the Tandy antenna is getting a bit sick up at analogue Channel 10.

Digital TV reception is excellent for Channels 7, 9, 3, and 44 but is dodgy on Channel 10 and Channel 2. Channel 10 digital is the worst performing channel.

My Strong PVR gives the following numbers for signal strength/quality with the Tandy/K-Mart antenna:

(Ch7 83%/95%, Ch9 85%/95%, Ch10 81%/47%, Ch2 73%/50%, Ch44 83%/95%, Ch28 99%/95%)

The above figures show why digital Channels 2 & 10 are bad performers. This is so particularly with a north wind which has the 33KV trunk line producing plenty of impulse noise.

Anyway, I replaced the Tandy UHF/Antenna with a MatchMaster 01M-LP03F log-periodic antenna. Matchmaster actually recommend the 01MM-DC21A antenna for my location on their web antenna selection facility. However, my local Jaycar store had the LP03F in stock and it was only $79 instead of $149, so I figured I'd give the cheaper antenna a go. The performance figures seem much the same.

So, I've kept the existing UHF K-mart antenna (which has strong and excellent performance), and put in the Matchmaster in to replace the old Tandy UHF/VHF antenna.

I'm only using the UHF performance of the Matchmaster antenna, because of the old Tandy masthead amplifier requiring separate VHF and UHF antennas.

My Strong PVR gives the following numbers for signal strength/quality with the Matchmaster/K-Mart antenna:

(Ch7 90%/95%, Ch9 85%/95%, Ch10 85%/95%, Ch2 82%/95%, Ch44 82%/95%, Ch28 99%/95%)

So, the Matchmaster log-periodic antenna has improved Channel 2 and Channel 10 reception to aproximate the Channel 7 and 9 performance with the old antenna system.

The FM radio signal strength has dropped compared to the old antenna, but is still quite workable. The DAB+ radio seems to have perfectly adequate signal strength and is apparently working well as I write this.

So far I'm jolly pleased with the results. Channel 2 analog even still works after a fashion, and is quite watchable in an emergency, which I didn't expect at all., since the Matchmaster is a Channel 6-12 antenna.

I'll be interested to see what happens with a north wind which usually has the 33KV trunk mains generating plenty of impulse noise. I have a heat wave/north wind coming soon, so I ought know how the new antenna copes in a week or so.

So far I'm very pleased with the results. :)

Ross

Reply to
RMD
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Hi All,

We are in a heat wave here and the 33KV trunk main insulators are breaking down and producing quite severe impulse noise. This is visible as dashes on the screen from analogue Channel 2 to analogue SBS, and is breaking through the FM sound too.

The new antenna setup has produced a fairly significant improvement in performance of previously susceptible equipment, but hasn't resolved the problem completely.

I've found for best noise resistance the TV signal needs to be in the "Goldilocks zone" for any particular piece of equipment. In other words signal levels need to be "just right".

The only problem is that the Goldilocks zone can differ for different digital TV devices. I have some Dick Smith variable gain booster amplifiers and using these to raise/lower the input signal level can help in finding the aerial signal "sweet spot".

Even given the optimum signal level, then different tuners perform better than others, and price is no particular pointer in regard to this tuner performance.

I have a fair idea where particular tuners fit in the performance heirarchy, but recently I rewired an antenna feed arrangement which was feeding, amongst quite a few other things, a Telstra T-box. I think there was possibly a dodgy cable interconnect somewhere in this particular antenna feed leg.

Anyway, the Telstra T-box is now the best performing tuner in the house, whereas before it was one of the worst. Other tuners on the same feed are quite a bit better too, but not by such a lot. Somehow it happens that signal conditions are now really optimum for the Telstra T-Box.

I also find high impulse noise levels can produce all sorts of equipment operational weirdness.

For example, PVR's start recording but don't ever stop recording. Repeat recording times can suddenly skip a week. Using the remote control to set PVR's up can result in quite erratic behavior, and pulling out the aerial feed fixes the problem and stops the operation erratic-ness.

In fact, it is easy to think that the dodgy equipment has suddenly developed an intermittent fault. Except that pulling out the aerial feed cures the problem.......... And the very next day without high impulse noise levels about then the equipment is back to being quite docile and well-behaved again.

Luckily most of this really quite bizarre behaviour only happens quite rarely on really bad impulse noise days, and these bad days don't actually happen all that frequently.

There is also a variation in impulse noise during the day. It usually gets gradually worse as the day progresses, but then gets better during the evening and often about 8pm or so the impulse noise completely disappears until about mid-morning the next day.

Anyway, this diurnal effect means much evening viewing works out fine. Recording things at midday or afternoons is usually the worst time, if there is going to be trouble.

Anyway, with the new antenna setup, then SBS is the most reliable feed, followed by Channel 7 and 9. Channel 2 is usually better than Channel 10, but not always.

If everything performed as well as SBS does then I wouldn't have much of a problem.

Ross

Reply to
RMD

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