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206 posts

Master Geek
+1 received by user: 1

Topic # 74607 3-Jan-2011 20:18 Send private message

I still have some TV's in the house with no Freeview so still using the in-built analog tuners.

I get perfect reception in Devonport, Auckland on all channels (analog and Freeview) except TV1 analog (Ch2 off Waiatarua).

Is it possible I am getting interference from the FM radio station transmitters on the Sky Tower (which is very close to Devonport relative to Waiatarua). I have heard of this issue in Devonport a few years ago.

If so, I was wondering if an FM Filter installed in-line on the TV aerial cable might help.

If so what type do I need and where could I buy one (preferably from some place that I can return it if it doesn't help).


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1530 posts

Uber Geek
+1 received by user: 55

  Reply # 423877 4-Jan-2011 08:07 Send private message

In my experience the old analogue Tuners seem to be pretty good at rejecting unwanted signals. It's more likely an antenna problem and a filter would be a waste of time and money. All the Transmissions from Skytower only cause me problems on my modern amateur radio receivers with very wideband front ends with little or no selectivity. Do you have a VHF/UHF antenna that covers all channels or just a UHF antenna? Ch1, 2 and 3 are low band VHF which requires a fairly large antenna. A small UHF antenna may be OK for Ch 4 and higher but not for the lower channels. Old weather-beaten antennae and coax add to the problem. Devonport would be a prime location for salt induced corrosion.

206 posts

Master Geek
+1 received by user: 1

  Reply # 423900 4-Jan-2011 10:52 Send private message

I have a new aerial and Sky quality cable. The aerial is VHF/UHF combined with in-built diplexer.

I have tried everything, including just using a VHF aerial and only 10 meters of cable, in this case the signal improved slightly, but still TV1 is no where near an acceptable level of quality compared to other VHF stations and the UHF stations.

1530 posts

Uber Geek
+1 received by user: 55

  Reply # 423994 4-Jan-2011 17:57 Send private message

Have you tried tuning TV1 (Ch 1) from Skytower? It may be close enough physically and in frequency to be causing problems although I think it may be vertical polarisation and low power?

206 posts

Master Geek
+1 received by user: 1

  Reply # 424002 4-Jan-2011 18:31 Send private message

No I hadn't.

For some reason I did not think TV1 was on SkyTower.

Is it UHF or VHF and what channel

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Uber Geek
+1 received by user: 55

  Reply # 424046 4-Jan-2011 20:38 Send private message

I'm pretty sure it's Channel 1 Vertical polarisation. I've been trying to find a list of local transmission sites on the web without success so far. Used to be easy to find. I do know there is definitely a CH1 Transmitter there.

206 posts

Master Geek
+1 received by user: 1

  Reply # 424051 4-Jan-2011 20:48 Send private message

Try this site - it suggests no TV1 on Sky Tower.

1530 posts

Uber Geek
+1 received by user: 55

  Reply # 424053 4-Jan-2011 20:57 Send private message

Sorry Steve2222.
You are correct. I knew there was a CH 1 Transmitter there but just assumed it was a fill-in for TV1. And I see it is horizontal. It may be that there is sufficient power on multi VHF channels at Skytower to affect your Ch2? The amount of rf radiating from the tower sure wipes out my mobile VHF/UHF rx when in sight of the tower. Looks like all our old analogue sets will be redundant in a couple of years anyway. Also means the analogue transmitters will disappear from Skytower.

295 posts

Ultimate Geek
+1 received by user: 20

Chorus NZ

  Reply # 426458 12-Jan-2011 11:26 Send private message

The VHF-TV Broadcast from the Sky Tower is: VHF Ch 1 (This is C4) & VHF Ch 5 (This is TV3).

The first thing to check is what kind of VHF Antenna do you have? There are two bands to pick up on VHF-TV (VHF-Low & VHF-High). VHF-L needs elements on the Antenna that are about a metre or more wide and VHF-H needs the shorter 40cm or so ones (with UHF Antennas being about 20 cm width).

Waiatarua broadcasts TV1 on VHF-L (Ch2) and TV2 (Ch7), TV3 (Ch9) & C4 (Ch11) on VHF-H. So if you don't have VHF-L elements you will probably be in trouble.

206 posts

Master Geek
+1 received by user: 1

  Reply # 426655 12-Jan-2011 21:53 Send private message

Thanks for the reply.

Aerial specs said it covered ALL VHF channels.

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