ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades TV Troubles

Ahhh, the fun of MATV setups gone bad!

Albiet, nowadays (since 2001 to be exact), equipment is easier for end users to obtain, install and configure (plus plan out!) - resulting in a record low in panic calls to "come fix it!!!"
Haven't dealt with any calls for almost 2 years!

Now prior to that (<2001), things were much different, and had many odd mismatches and incorrect connections to deal with.

Problems ranged from the very simple, to the very extreme, as:

• Incorrectly setting TV/VCR to a "Dead" VHF channel - typically Ch 03 (60-66 MHz),
• Inputs/Outputs swapped,
• RCA type patchcords for line level patching either in bad shape, or patched thru incorrectly,
• No AC power to preamps, dist. amps or MUX(es),
• Really crappy make-up on "F" connectors, loose and / or incomplete connections,
• Using RG-59u Ethernet type coax (10 base 2) with RG-6 coax and connectors, or RG59 connectors on RG-6 cable,
• Using Ethernet 10 base 2 coax - with / instead of - RG-6 cable,
• Connecting any type of 75 ohm Z coaxial cable directly to 300 ohm Z terminals, without going thru a Z matching transformer,
• Long unamplified looped runs, using a bunch of 3-way splitters,
• Driving VCR output, or CATV input, directly into a VHF/UHF Antenna,
• Poor connections thru RF switching items - such as Video Game Interfaces,
• Broken RF in/out connections on TV or VCR,
• VHF / UHF Antenna setup and aiming problems,
• DBS Antenna setup and aiming problems,
• Kinked feeders (causing standing waves),
• Being stepped on by other broadcasted stuff (herringbone effects from HAM setups, etc.).

Ran into all sorts of issues with VHF / UHF Antenna setups.

The typical Antenna for multiband TV here is the Parasitic Yagi.

The larger VHF section consists of a Log-Periodic Dipole array, which the driven element is located near the UHF section at the front, and the reflecting elements can be "swept forward" (angled to 60°) to increase gain of lower VHF band, or not swept (straight / 90°) for normal overall gain.

The UHF section is typically a multi element Dipole arrangement - sometimes using a "Bow Tie" - and normally surrounded by a corner reflector array (reflectors above and below are 45° + and -).

Antenna problems include Off-alignment, 180° alignment (facing backwards), ½ the elements swept back, swept elements laying on unswept ones, damaged, missing or broken rear reflecting elements, other elements missing or damaged, reversed UHF reflectors (seriously!), damaged, missing or "tweeked on" driven elements and/or connections to it,
no Z matching transformer (mentioned before), bad mounting location or height, and use of 300 ohm Z lead in wire which is in bad condition, plus is strapped directly to Antenna mast, other cables, metal pipes, etc. (run without stand-offs).

Some of the location problems result in "Ghost" reflections from trees and buildings.

Some "Fringe Areas" have low power problems, which usually result in channels being stepped on, or just turn out to have a solid "Ant Race" over a snowy picture.

The Hz's here cover:

<OL TYPE=1>

[*]Lower VHF TV Bands (Ch. 02 thru 06): 54 MHz thru 88 MHz,

[*]VHF FM commercial Radio: 88 MHz thru 108 MHz,

[*]Upper VHF TV Bands (Ch. 07 thru 13): 176 MHz thru 216 MHz,

[*]UHF TV Bands (Ch. 14 thru 83): 470 MHz thru 890 MHz.
</OL>
TV channel occupies 6 MHz, whereas the FM Radio channel occupies 200 KHz.

Just some FYI

Scott35

p.s. Thanks, Paul, for the thread!

The combination VHF/UHF TV antenna never caught on here, due to the nature of our separate 405 and 625-line services.

Basically, up until the 1960s TV was on VHF only using the 405-line system. In 1964 the second BBC service was opened, using the new 625-line UHF allocations. Dual-standards receivers appeared at that time, with separate VHF and UHF tuner inputs, and anyone in the BBC2 service areas thus needed both UHF and VHF to receive all three networks.

BBC2 started regular color broadcasts in 1967, and in 1968/69 the other two networks also started opening color transmitters on 625/UHF. The 405/VHF services continued to simulcast signals (in black-&-white only) until 1985, but of course anyone wanting all three stations in color had to switch to UHF. It was only a few years before all new sets in the U.K. came equipped with just a UHF tuner for the 625 system.

This is our typical UHF antenna.

We have a number of narrow band UHF yagi type antennas in use exclusively for picking up RTE/NET2/TV3 & TG4 on UHF only.

These are colour coded depending on the channels a particular transmitter or relay is using.

This type covers everything, including rebroadcast UK channels on "deflector" systems.



End of an era:
VHF is gradually being switched off as its bandwidth is being swollowed up for various digital broadcast services etc.
here's how its done:
Taken from a Cork City VHF PAL 625 line broadcast of RTE 1



[This message has been edited by djk (edited 08-02-2003).]

I think you use the same UF aerial grouping as we have in the U.K.:

Group A (red), ch. 21 - 37
Group B (yellow), ch. 35 - 53
Group C/D (green), ch. 48 - 68
Group E (brown), ch. 39 - 68

Most installations use a group A, B, or C/D antenna, but group E is specified in a few areas where the channels couldn't be kept all together within one of the other
groups.

Wideband aerials (group W, black) are also widely available.

Just to complete the picture for anyone not familiar with our channels, the UHF band runs 470 - 854 MHz with 8MHz channel spacing.

djk,
That's a good pic of a Phased Array UHF Aerial, we get really good results over here in NZ with these aerials, but boy are they expensive, so we normally end up using a Yagi-type Aerial arrangement, for most customers.
Paul,
I went to do a Fault-finding job on a customers set-up the other day.
And I have to say, that it was the tidiest, most well thought-out TV/Radio/DVD/VCR and Audio Reticulation System that I have EVER
seen put into a house by anyone!.
Everything was marked correctly and at ALL plugs, he had a system diagram with coded outlets and he had a "Central Systems Hub" in his roof void, where he had all the system amplifiers, connectors, etc, all neatly laid out in a way that would make a TV systems tech shed tears(Why aren't they all like this?).
We got to talking and I found out that he was a Labourer that had scraped and saved for the last 10 years to make up and install this system and I commended him on his eye for detail.
The reason I was called there though, was because he had no Terrestrial TV (VHF/UHF) reception, which I traced(by use of my trusty Field Strength Meter) to a cut down-lead as it went into the house under the steel flashing(another guy had installed the aerials, due to the owner being scared of hieghts), so I pulled in a new D/Lead and sealed the area where the cable entered, with RTV to prevent the cable being cut again, too.
We checked the picture on his Big TV and he was happy!.

Wow! All neat and tidy, AND everything labeled -- Now that's a rarity!

I haven't expanded upon this part yet:
Like many TVs these days, this set was obviously designed for use in different world markets and had the typical modern array of on-screen menus to set up everything. The manufacturer often uses the same basic programming for every set in the range but masks out menu options which are not needed for a particular country/area or for a particular model.

This set looked as though somebody hadn't quite decided where it was going to be sold!

The manual stated PAL system I (U.K./Ireland) and B/G (most of Europe, except France). Like many new sets, it has auto-tune and pre-programmed lists of stations for each country so that they can be put on the presets that most people use (e.g. 1=BBC1, 2=BBC2, 3=ITV, etc.). The channel listing options had U.K., Germany, and a couple of other European countries which I forget, but also included the French listings. But the set had no facility for switching to SECAM system L for France!

Despite the manual indicating that the model was also sold for Ireland, it had no Irish station lists, nor was there an option to select Irish VHF channels (which are different to European).

It did, however, have the option to switch to OIRT (Eastern Europe) channels, and the menu allowed switching to NTSC as well! (Though there was no way to select American VHF/UHF channel allocations.)

The illustrations in the book (which clearly stated PAL-only in the specs for this model) showed brightness, contrast, color, andhue adjustments. The owner assumed something was wrong, because his menu didn't include the hue adjustment (I verified that it did appear when the set was switched to NTSC mode).

The average buyer is confused enough by all these different settings without being confronted with this sort of inconsistency as well.

As I already mentioned earlier, Asutria has 2 (now 3) terrestrial networks. ORF 1 is VHF ch. 1, ORF 2 is something like UHF ch. 34 (lotsa interference with nearly all VCRs being UHF 36) and the new private ATV+ is somewhere in the higher UHF area. Many people here just have a small VHF/UHF antenna on top of their TV set. 2 rods for VHF and a Dipol for UHF, or even just the 2 rods sticking out of the top of the TV set. VHF reception is usually quite good, ORF 2 is poor and ATV is terrible (mostly black&white and lots of ants running), so some people start resorting to amplifier antennae. These usually boost up ORF 1 to more or less perfect and ORF 2 to viewable (at least in our area of town, somewhere else it might be very well the other way round). The only way to get decent ORF reception is cable TV.
TV and radio licenses are still needed here and not too cheap, I think something like 22 Euro per month. The license specifies how many TV sets and radios you're allowed to run. A license is even needed if you only have satellite TV and no antenna.

Paul,
With respect to a "Wide-Screen" TV.
I realise the size of a screen is related to the Aspect Ratio, but does a wide-screen TV have an Aspect Ratio of 16:9?, or some other figure?.

[This message has been edited by Trumpy (edited 08-16-2003).]

I've noticed that with TVs here too.

I think it's a little more than just software to save cost they have one basic TV unit with different tuner moduels that can be plugged in for different markets during manufacture. The TV itself will be exactly the same, the software will be the same but certain functions may be different. A French version will suport SECAM and French channel system. An Irish TV will incorporate a VHF and "Cable Hyperband" tuner as well as UHF. The UK version will simply have UHF etc etc.

As for the Manuals they're often very generic and badly written so may just include absolutely everything with **
** = Not applicable in the UK, Germany, Ireland etc..

Most TVs here auto tune the channel names too although get them slightly out of date.

They should read:
RTE 1, NET 2 (since 1988), TV3 and TG4

But you always seem to get:
RTE1, RTE2, TV3 and TnaG

Our sony TV seems to support just about everything in Europe.

It gives a list of countries and you just pick which one you're in. Seems to have no problems supporting SECAM or PAL I/B/G etc..

Trumpy:

We usually have a pair of those phased array aerials