Just When Should An Aerial Be Replaced?

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1gkar

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Topic # 27474 27-Oct-2008 18:25

I been having playback issues which are most probably aerial/cable related -I think. I have disconnected the splitters to other components & plugged the aerial cable directly into the HVR-2200 tuner with no discernable difference in playback issues. I have also redone the connection to the aerial connector box. Have been unable to check it to date as I only completed this earlier today. The issues are most notable when both DVB-T tuners are in use. LiveTV seems to be more stable for some reason.

I have this aerial installed & has been in place for some years, now. The back

wire collectors are rusted, with what I would term as invasive -areas of the wire have rust bubbles. The question I have is, does this collector make a significant contribution towards a constant, stable reception?

I am going to replace the coax cabling. Thanks.

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rscole86

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Reply # 173907 27-Oct-2008 19:06

You need to fix the URL for your picture, we cannot see it.

mcraenz

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Reply # 173909 27-Oct-2008 19:08

Where abouts are you, I'm in central Akl city, but down behind a hill, I replaced my smaller rusty UHF with that same whopping big 91 element, I tried it first without the amp that had been previously attached but it was hopeless, added the amp back in and all is ok. What's your picture like on prime analog?

I have one of these amps, but an amp is a last resort since it can create more problems that it fixes.

Oh yeah, I used quad shield coax too:

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cyril7

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Reply # 173950 27-Oct-2008 21:12

It would help if you could post your suburb and what Tx are you aiming for, do you know what C/N ratio, or MER or BER ratios are recieved at your location. The number of tuners in active use should make no difference as they are all active at all times (that they are powered) anyway.

Cyril

1gkar

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Reply # 174712 30-Oct-2008 18:56

@rscole86 -I removed it because everytime it loaded a www.geekzone url prefix

@mcraenz -I live in Blockhouse bay, in Rathlin St, which does not have line of sight to the Waiatarua transmitter, to which the aerial is pointed. Prime is excellent, if a little soft in definition -which is most likely attributable to being SD, with no picture flaws.

@cyril7 -As mentioned, the aerial is aimed at Waiatarua. Afraid I do not know the C/N, BER or MER ratios. How do I go about finding out?

Since I redid the masthead connection, the picture has improved markedly. The only real time I had issues were last night watching Medium. I did a total of 5 records last night, of which only 1 was on a Non-Freeview channel (Prime) & Medium was the 2nd Freeview record. But it was still easily viewable. TV3 definitely is the most problematic for Freeview reception. All other records have been nearly perfect, unlike prior to the remade connection where I had to delete the V8 Supercars' recordings as they were running low frames with an audio faster than the picture.

Thanks to all for your assistance.

n00dy

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Reply # 174718 30-Oct-2008 19:29

any oxidisation / corrosion on an antenna / connectors / cable is bad, antennas in NZ are under constant attack from sea spray and as a result antennas need cleaning at least yearly. I use a fine wet n dry sand paper and clean down antenna elemets, I clean the connectors and replace is required, I sometimes trim back the coax to remove the oxidised cable and attach fresh copper to the terminals, then a quick spray with CRC, if you have a multi meter, check the Ohm resistance at the decoder end of the cable, this should reflect the condition of the cable and connections, think it is supposed to be 75Ohms, being that most our antennas are alloy you could find that the antennas need replacing every few years if close to coastal area

cyril7

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Reply # 174728 30-Oct-2008 20:38

check the Ohm resistance at the decoder end of the cable, this should reflect the condition of the cable and connections, think it is supposed to be 75Ohms, being that most our antennas are alloy you could find that the antennas need replacing every few years if close to coastal area

A resistance meter will measure the resistance at DC, this in no way reflects the impedance and 500-800MHz so is irrelevent, but ensuring clean corrosion free connections is a good idea.

Cyril

1gkar

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Reply # 174735 30-Oct-2008 20:57

Just a question on aerial construction. When I removed the antenna element with the coax cable box attached, I found a plastic spigot, as part of the weatherproof connector box, designed to enter into a small hole in the underside of the aerial's main square tube axis.

Given that plastic is an insulator, I would have thought some form of metal would be desired for optimal signal transference. This appears not to be the case: so how is the signal transferred between the elements & the cable? Please, only near-noob answers accepted