TV antenna

[VK5IR]

Hi all

This weekend I will be putting up a new outdoor TV antenna. My two little girls keep snapping the rabbit ears antennas I buy so I decided after many years to do it properly.

I bought a cheap VHF/UHF yagi from Dickies ($50) and I intend to mount it to the same mast I have my Station Master vertical mounted on that I use for 10 & 15 meters. I can't mount it anywhere else.

Am I doomed to face a life full of TVI? The TV antenna will only sit around a meter or so below the base of the Station Master.

Also, is RG59 ok to do the job or would you suggest I use RG6 and if so, WHY? Will it make any difference? Its only going be a run of around 10 meters max.

My digital TV reception has always been good even with the rabbit ears so I assume the cheap yagi will do the job. I've had a look around the neighborhood and its looks as if a lot of my neighbors are using a similar antenna.

Thanks for your help.

Theo.

[VK3DXE]

If you have a fairly recent TV and your TV signals are reasonably strong, then you shouldn't have too much trouble with reception.

In my experience, the biggest problems with digital reception "TVI" have been in marginal signal areas where the TV suffers desense from the TX and you start to lose signal over the precipise. Try running your TV antenna a little lower down the mast - less wind loading and a little further from your TX antenna, then see how it goes.

[VK2ZRH]

Hi Theo.

I embarked on a similar route last year. We're not by any means in a fringe reception area, but indoor antenna reception of the digital TV channels was pretty disastrous.

With the cheap outdoor "digital ready" (hah !) antenna installed at pretty much the closest possible point to minimise the cable run to the TV, it required some 20 metres of cable. On researching suitable cable, I was aghast at the "build" of various 75 Ohm cables advertised as 'UHF TV coax' (or similar). The specs for most RG59 and RG6 are - what shall we say - 'generic', and most likely don't equate with reality, particularly in view of my experience a while back in measuring some cables' loss characteristics.

I installed double-jacketed RG6, which I bought from a computer retailer at much less expense than even the 'budget' RG6 carried by several electronics retailers. Seems to work a treat.

However, while not able to measure digital stations' signal strength here, we do suffer picture pixellation from time to time and audio channel dropouts; some channels suffer more that others in this regard. By simple observation, it's pretty much weather related, wet and windy days being the worst, along with foggy mornings.

So. I'm considering moving the antenna - for a start - then designing, building and installing my own. It would have to be better than a bought one.

For you - my advice is: install RG6. But examine the 'build'. In particular, the 'better' cables have foil overlaid with close-weave braid and a white foam dielectric.

As for TVI, why not try attaching two quarter-wave coax shunt traps at the TV antenna feedpoint, one for each band. Any skungy coax will do the job, but use a dipper when cutting the traps to length. The other approach would be a pair of series tuned L-C traps, housed in a small plastic, weatherproofed, box.

73, Roger Harrison VK2ZRH

[VK2FXXX]

Gday

The Station master is an end fed antenna.
As such the needed"counterpoise" for the antenna is the coax and metal mast.
They will have significant amounts of RF on them when transmitting.
Whether this causes TVI is unknown ,but I would wager that it would.

The rf from the station master coax /mast would couple to the tv antenna coax.
If you cant put the tv antenna anywhere else, what can you do?
If you have tvi issues then try the suggested below.
Perhaps at least 4 radials at the bottom of the station master,plus a ferrite choke at the pl259,and also a ferrite choke aprox 5m down the SM coax. (at a current anti-node)
Also a choke or 2 along the tv antenna coax couldnt hurt.
Make sure the tv antenna has a balun.
You may get lucky ,and put the thing up, and have no issues.

If you want to learn more ,read these.
http://www.w8ji.com/end-fed_vertical.htm
http://www.w8ji.com/ground_plane_verticals.htm
http://www.w8ji.com/end-fed_vertical_j- ... l_zepp.htm
http://www.w8ji.com/common-mode_noise.htm
A bonus to doing the above, is that the pattern of radiation on 10m will be improved,
and also possibly on 15m as well.
Good luck.
Brendan

[VK2XSO]

On researching suitable cable, I was aghast at the "build" of various 75 Ohm cables advertised as 'UHF TV coax' (or similar). The specs for most RG59 and RG6 are - what shall we say - 'generic', and most likely don't equate with reality, particularly in view of my experience a while back in measuring some cables' loss characteristics.

The standards for RG59 and RG6 are not the issue. It's that the manufacturers of the cheap and nasty cables do not meet those standards.
In the past couple of years I have seen the change from using RG59 to RG6 because it was "better". (and not to mention cheaper).
In reality RG59 is the "better" cable. And this is not just considering insertion loss, which RG6 standard is slightly better.

Reality is that the cable that is being sold as RG59 is not up to the specification of such and is of such poor quality, that an already low quality cable like RG6 appears vastly superior. Using the specification RG59 will s**t it in over RG6Q or any other variation of RG6.
(RG6 Quad shield = If the job isn't worth doing once correctly, then it's worth doing four times poorly.)
But if you're given the choice of the cheap RG59 'type' coax, then you might as well use RG6 because it's slightly cheaper and has a slightly lower insertion loss than fencing wire.

RG6 seems to work without a problem for most people. However, if you have some mysterious problems like one or two digital channels are missing or pixelating or you already have the chance then use the proper RG59 then use it.

As for TVI, why not try attaching two quarter-wave coax shunt traps at the TV antenna feedpoint, one for each band. Any skungy coax will do the job, but use a dipper when cutting the traps to length. The other approach would be a pair of series tuned L-C traps, housed in a small plastic, weatherproofed, box.

Errr... I wouldn't do that !
Those notches extend up into VHF and UHF too ! You'll be notching out all kinds of frequency components. A bit of colour here, a sound carrier there, and a QAM Ayres rock will look like one of the Death Valley Mittens

Actually.... come to think of it.... that's what RG6 looks like on the network anaylser, like somebody has a big stub attached to it.

[VK2JDS]

use rg6quad, clipsal or digitek, use compression F's and adapters, use F wall plates with quad shielded F>pal cables to tv.
never use saddle and clamp plates or single shield rg6
if you can go to rg11 then do so.
rg59 commercially sold is rubbish.only the microwave version which is very expensive is worth looking at
i work in the industry.
73's

[VK5PJ]

Hi Theo,
once the outside antenna is up you may want to put a braid breaker in the line to the TV to reduce any stray RF frm the HF antenna that may travel on the outside of the coax or a small filter up near the antenna you can see what was done at my place by looing at this forum topic viewtopic.php?f=61&t=10120 I have had a month of worry free activity since putting the filter in line. My circumstances are a bit different in that I am fringe area but the premise is the same, in that keep the unwanted RF away from the TV front end.

Regards,
Peter, vk5pj

[VK5IR]

Somebody please correct me if I'm worng, but isn't RG6 a fair bit harder to terminate?

I think you need special crimping tools etc. or something, right?

[VK2ZRH]

isn't RG6 a fair bit harder to terminate?

Nope. It's for TV. Use F-connectors.

However, I chose to put a break in the cable for my installation, in order to experiment with antennas (if the cheap retail one was unsatisfatory, or I just felt like experimenting). For that, I used Belling-Lee connectors. Pretty straightforward.

73, Roger Harrison VK2ZRH

[VK5IR]

isn't RG6 a fair bit harder to terminate?

Nope. It's for TV. Use F-connectors.

What hardware is required to terminate RG6 & RG59 for TV use?

A big thanks for everyone's help.

[VK2XSO]

What hardware is required to terminate RG6 & RG59 for TV use?

That's an interesting question actually.
For RG6, it should be a copper solid center conductor with a tinned copper braid. But the common RG6 is a steel copper plated center conductor with a loose braid and a plastic/foil shield.

F connectors are made for RG6. But you can get BNC and Belden style connectors for it though they're not so easy to install.
There are two types of F connectors for RG6. Crimp and Compression connectors. There is not difference in performance with these two types of F connectors.
Compression connectors use more expensive tooling and they look better, but that's their only advantage.

Crimp F connectors for RG6 are the easiest to install.

RG59 should have a multi strand copper core and a thick weave copper braid. You should not be able to see the dielectric through the braid and when the PVC jacket is cut off the braid should hold to the cable and not fray or fall off.

The stuff Jaycar sells, the braid it thin and consists of a few thin wires that might have traces of copper.
The braid will usually fall off and definitely fray as soon as the jacket is off.

Belden PAL type connectors I doubt are made to suit any particular cable. But they've been the standard connection for Australian TV's.
They are reasonably easy to terminate to the propper RG59 without any special tools. A screwdriver and a pair of scissors is usually enough.

If one was really serious about quality, then they'd use crimp style BNC connectors which offer excellent performance.
75 ohm N type connectors are also available. I would not be surprised if a 50 ohm N connector version is also available.

A bodgey F connector is also available for RG59.


I don't know anybody who uses BNC connectors for the TV cabling. (Ok, I might use them in a few places), but they are overkill.
Belden or F type connectors are both suitable. I feel F connectors are mechanically superior as they don't come loose like the PAL connectors.

[VK2GFR]

I think Trash was actually referring to...
Belling Lee Metal TV PAL connectors.
Belden is the manufacturer of the RG6 Quad &Tri-Sheild Coaxial cables.
A word of caution ... NEVER use plastic moulded style do-it-yourself PAL connectors, they are not strong enough to be used on RG6, RG59 (or in my opinion ANY tv coax cable) ONLY use the METAL PAL type.
Oh & use metal F type splitters, also earthed as this will diminish most of the suseptibilities of "glitching" or pixalation from external sources.
But it will NEVER completely stop the light swithes causing it, as all switches are a make n break contact.
Its a fact of Digital TV life.... oh the joy of it all.

Oh Theo, take a look at the Filter mentioned elsewhere in this forum (from a VK4) in regards to eliminating amatuer radio upsetting the family's digital tv experience. I had severe break up on Ch10D here in Sydney, built the filter & voila, the problem is no more! (and that was without any major adjustments to the design at all) I never had to use a spectrum analyser either. A damn good project it was!!!