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10 posts

Wannabe Geek


Topic # 113676 24-Jan-2013 10:16 Send private message

I think the aerial on my roof is VHF but I'm not sure. Maybe someone can identify it from the picture below. I can pick up Freeview with it but TV 1, 2 and U (all on same channel) are patchy and sometimes unwatchable. All other channels are good. If this is a VHF aerial does it mean that the signal is strong when I can pick it up with this? And would that mean that pretty much any type of UHF aerial would do the job ok? I am in the Brook in Nelson and my local transmitter is Kaka hill, approx 3-4Km away. The Brook is a valley so I'm not sure if there is direct line of sight, but the indicative coverage map indicates 'very likely' for my area. I'm just wondering if I could select a UHF antenna myself or if I would be better off to get a professional to come out and tell me what type of aerial would work best.



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1373 posts

Uber Geek
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  Reply # 750041 24-Jan-2013 10:26 Send private message

I think the aerial on my roof is VHF but I'm not sure. Maybe someone can identify it from the picture below.

Yes. It is a combined High band/Lowband VHF.


I can pick up Freeview with it but TV 1, 2 and U (all on same channel) are patchy and sometimes unwatchable. All other channels are good. If this is a VHF aerial does it mean that the signal is strong when I can pick it up with this? And would that mean that pretty much any type of UHF aerial would do the job ok?

Probably. If you are getting pretty good signals already then just get a new UHF antenn and connect to the current co-ax. If still patchy on the TVNZ mux then replace the co=ax as well. Dick Smith has a good self install deal on UHF Antenna at the moment for around $50.


I am in the Brook in Nelson and my local transmitter is Kaka hill, approx 3-4Km away. The Brook is a valley so I'm not sure if there is direct line of sight, but the indicative coverage map indicates 'very likely' for my area. I'm just wondering if I could select a UHF antenna myself or if I would be better off to get a professional to come out and tell me what type of aerial would work best.


Selecting and installing your own is easy and cheaper.
This site might help

http://www.freeviewshop.co.nz/information/technical/aerial-guide-i-49.html
http://www.freeviewshop.co.nz/digital-terrestrial/terrestrial-aerials-c-11/conventional-aerials.html


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  Reply # 750044 24-Jan-2013 10:30 Send private message

P.S. It also looks like the front part of the antenna (the short elements)  in the picture is UHF but combination antennas are not usually very good for UHF only reception. May be OK when analogue switches off but you will be getting a lot of analogue signal on that antenna as well as Freeview at the moment. This can upset a lot of tuners. Some Panasonic Recorders don't like any VHF analogue present on the input.



10 posts

Wannabe Geek


  Reply # 750059 24-Jan-2013 10:55 Send private message

Thanks very much for the helpful response. I had a look at the Dick Smith site but didn't see the $50 deal you mentioned.
http://www.dicksmith.co.nz/tv-video/antennas/outdoor-antennas

Currently they have just 4 antennas listed:
Dick Smith HD UHF Outdoor Antenna Pack
HILLS 43 ELEMENT HD READY UHF OUTDOOR ANTENNA
UHF Phased Array TV Antenna
UHF TV Antenna 43 Element  Which of these would you go with in my situation?  freeviewshop.co.nz also has 6 outdoor antennas on offer: 21, 47 and 91 element aerials, triple folding structure, large and medium phased arrays.
Is there a downside to having too many elements?

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  Reply # 750138 24-Jan-2013 12:53 Send private message

aidanc:
Currently they have just 4 antennas listed:
Dick Smith HD UHF Outdoor Antenna Pack

Is there a downside to having too many elements?


That was the one. Was $49.99 for the last few weeks. I see it's back to $99.99 again.

More elements just make the antenna more directional and increase the gain slightly.
A 43 element should be OK in your location. I installed one at my Son's place in a valley in Glenfield way out of line of sight of Waiatarua and works well. Signal strength around 80 - 90%.
You could try just removing the VHF elements from your antenna and see what happens although I see what looks like a balun connecting the co-ax to the antenna via 300 ohm ribbon. That's not good for UHF and it's probably all corroded and rusty as well. Nothing beats a new antenna and RG6 co-ax.



10 posts

Wannabe Geek


  Reply # 750232 24-Jan-2013 14:41 Send private message

Ah ok, I'll look for it on sale again.

Here's a closer picture of that connector that you think might be a balun:


It doesn't have ribbon coming out of it, just 2 wires that connect by wing nuts to the aerial:



and here's a closeup of some of the elements that you think might be for uhf:



I'm hoping the coax doesn't need to be replaced as routing it through the walls would probably be a tricky. Is RG-6 a new type of coax or would the old likely be RG-6?

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Uber Geek
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  Reply # 750234 24-Jan-2013 14:48 Send private message

That is a balun.

The old coax is most likely RG59 - will probably be stamped on the side.

RG6 is generally considered a better option, and suffer less signal degradation over the length.

Can you use the old cable as a draw to pull through the new cable?



10 posts

Wannabe Geek


  Reply # 750271 24-Jan-2013 16:04 Send private message

Possibly, but it might be a bit of a mission, as I think it goes into the attic, down through one wall, under the floor and up through another wall. Crawl space under that floor is practically non existant. I think I'll try sticking with the old coax to avoid all that. Will I need any special connector or tools to connect in to the existing coax?

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Uber Geek
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  Reply # 750287 24-Jan-2013 16:16 Send private message

aidanc:Will I need any special connector or tools to connect in to the existing coax?


Depends on the connector on the new antenna. If it is a saddle clamp, then no special tools. If it has an F connector, then you'll need a crimp tool for that type of connector.

Be aware that using cable with a stranded centre conductor will be problematic with F connectors through (if that is what your current cable is).

255 posts

Ultimate Geek
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  Reply # 750304 24-Jan-2013 16:36 Send private message

The Brook is very patchy, probably need a high aerial,




 

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Ultimate Geek
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Trusted

  Reply # 750317 24-Jan-2013 16:53 Send private message

aidanc: Possibly, but it might be a bit of a mission, as I think it goes into the attic, down through one wall, under the floor and up through another wall. Crawl space under that floor is practically non existant. I think I'll try sticking with the old coax to avoid all that. Will I need any special connector or tools to connect in to the existing coax?


Looks like it may be RG6, but generally those Baluns get moisture / water inside
so you may have to chop off , strip back & put on a new connector



10 posts

Wannabe Geek


  Reply # 750327 24-Jan-2013 17:04 Send private message

injuised: The Brook is very patchy, probably need a high aerial,

I'm midway up Sowman St, so uphill a bit on the 'right' side of the valley. Looks like signal should be good according to indicitave coverage map:

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Uber Geek
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  Reply # 750329 24-Jan-2013 17:10 Send private message

Yeah.
Looking at the pictures I'd dump the whole antenna. Plenty of corrosion there and rusty nuts and bolts.
The co-ax might be used again but only if it has solid copper core so you could use a crimp or screw on f connector with a new antenna.
RG6 is what's used on Sky installations and is really the only type worth using. Crimp on f connectors are best but I've used screw on type and no problems after 3 - 4 years outside  in the weather here in Auckland.

238 posts

Master Geek
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  Reply # 750373 24-Jan-2013 18:42 Send private message

+1

While RG6 is definitely the preferred cable, I think RG59 is quite adequate on short runs (say up to about 20m).

Hopefully your new aerial will simply have an F connector socket for its outlet. Make sure you know which type co-ax you have if using screw on F connectors as they have different size threads.

Also I'd recommend getting a rubber boot to slide over the connector and/or some PIB tape (Polyisobutylene self adhering tape) to make it as weatherproof as possible' Also some cable straps to fasten the co-ax to the hockeystick.(after you've checked it's all working).

If you have enough slack cable, maybe you can drop the end back down to an inside window as it'll be easier to terminate indoors. You may also need a soldering iron to tin the inner conductor in the unlikely event it is stranded wire.

And don't forget to slide the rubber boot on before attaching the F connector.

255 posts

Ultimate Geek
+1 received by user: 3


  Reply # 750390 24-Jan-2013 19:29 Send private message

aidanc:
injuised: The Brook is very patchy, probably need a high aerial,

I'm midway up Sowman St, so uphill a bit on the 'right' side of the valley. Looks like signal should be good according to indicitave coverage map:


I wouldn't trust that coverage map, from memory there's trees on that hill right in the LOS, pay to use a phased array




 



10 posts

Wannabe Geek


  Reply # 750407 24-Jan-2013 20:40 Send private message

There's no markings on the cable but I opened up the cover on the balun to get a look at the coax and it looks like the core is stranded. You can't see it in this picture but here it is anyway. So it must be RG59.


I had a poke around in the attic to figure out how the cabel is routed and I see that it goes into a splitter with 4 outputs. We don't have TVs on any of the other outputs apart from the living room output.



After the splitter the cable to the living room goes into a 'black hole' which presumably takes it through an inaccessible part of the roof (over an extension without an attic area) and down the living room wall.

So I could easily replace the 3-4 meters of cable back as far as the splitter but fishing the cable up through the wall (2m) and through the blind cavity in the lean-to roof (4-5m) would be a risky undertaking.



So I'm thinking I would just run new RG6 cable back to the splitter. Is it ok to join up different types of cable at these splitters? Am I loosing much signal by having the splitter in the first place? Maybe I can replace it with some type of end to end connector.

The thing is that I'm pretty close already to having a workable signal. It's good on all channels expect the group on channel 40 (TV 1, 2 and U) and even those channels are fine half of the time. So I figure that just improving a part of the system would make enough difference.


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