tv ariel

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember The Natural Philosopher saying something like:

Tell that to the ants.

[Terry Casey]

A lot of transmitter sites need new aerial arrays to handle the full power transmissions after ASO. The means operating at reduced power or using a reserve aerial lower down the mast (same effect) while the work is going on. So yes, the signals are being deliberately reduced but not for the reason you have guessed at!

You should be able to find web sites which give information about such works. You will need to know which transmitter you are using - I note that neither of you have have provided this information which won't help anybody to give you any advice specifically of use to you.

[spamlet]

Thank's Terry,

I think somebody mentioned transmitters: Crystal Palace in particular. Don't know how to tell which one /ones I'm using anyhow. Could play with the tv tuning but it probably isn't worth the bother when I'm unlikely to be recording from it.

Good to know I may not just be imagining things!

Cheers, S

[Alan]

In message , spamlet wrote

Put you post code into

[Bill]

In message , Alan writes

instance it tells me I need an extra high gain amplified aerial to receive a station that I can see on a screwdriver stuck in the serial socket of the TV!

>

[PeterC]

Same here (although a bigger screwdriver, at 43km). Only 5 is poor but watchable on ~30yo aerial and co-ax. I was going to have a new aerial fitted; would have needed log-periodic for Oxford as it's wideband, but by delaying until March 2011 can have a C/D one for digital signal.

[Terry Casey]

The gain of a yagi aerial drops off very sharply above the highest frequency it was designed for.

Group A used to stop at Channel 34, with several channels between Group A and Group B being reserved for non-broadcast use.

It was eventually decided to release Channel 37 for use by (Channel) 5 but all the Group A aerials then installed didn't cover that channel! (Modern Group A aerials now cover a wider span and DO include Ch37.)

Therefore, your 30 year old aerial (assuming we're talking about Gp A) and my 40 year old Gp A aerial don't perform very well on 5.

[PeterC]

Ah, I wondered why such an old aerial was so good (apart from the co-ax has a lot of copper in it - better than so-called 'satellite' stuff).

I was impressed when the riggers fitted what looks like a good log-periodic job next door and not bacofoil, so I'll get that company to do mine.

[Alan]

In message , Bill wrote

I don't think it gives any other advice about the type of aerial. You cannot go far wrong with a DAT75 and a high gain masthead amp :)

I ignored their advice and went for a log periodic pointing at a transmitter 18 miles away (wideband is required for the transmitter)

[spamlet]

Hmm, looks like possibly Hemel: but the terrain is a bit iffy, so it might be CP even though it's further away.

Interesting - if academic, as I'm not getting up there to try moving it. Shame we didn't have this exchange last year as we has scaffolding up for a new window then!

Cheers, S

[tony sayer]

Theres not that much you can do with a Yagi to broaden its gain whilst keeping the bandwidth despite how many fancy director system you come up with or how bright the plastic bling;!..

[tony sayer]

Its more to do with the screening than the copper. Some very expensive cables use copper plated ally inner conductors!...

Logs are fine for very flat gain over the band .. but gain is what there're not that good at;!..

Side rejection is very good tho..

[tony sayer]

In article , Alan scribeth thus

Yes you can if there're strong analogue transmissions from the same site as the weaker DTV ones;!..

If the signal strength is there a log is a very good wideband choice 'tho sometimes if your DTV etc is in a fixed group band then a good Yagi design can sill give it a run for the money....

[PeterC]

Ouch! - I remember when the local 400kV line was renewed: compacted ally and bloody noisy it was too (audibly).

Necessary here, as next door's roof is a few degrees off the line and half a house-pitch to one side.

[The Natural Philosopher]

Oddly enough that is actually what suits many people: The transmitters are in general not far away for TV, its the multipath and the other stations that get collected that cause problems on digital in my experience.

Ok I have a distribution booster, but the set top boxes always report good signal levels, but poor signal quality when I have 'issues'

I ought to replace teh analogue with a good log wotsit in the loft..

[The Natural Philosopher]

I just looked at the maps and lined mine up with a compass.

[<me9]

Multipath performance is much better on digital than analogue.

The biggest problem (other than in group A areas) is that STBs can't differentiate between weaker out of area stations on lower channels and the correct local signals, as they scan the bands from low to high. This will result in poorer reception, and as was found in the Winter Hill switchover, reception of the wrong regional programmes. A workaround for this is to remove the aerial until the auto tune has passed the lower channels. A better solution would be for the firmware to ask for the postcode or local transmitter, as some of the computer TV card software does.

[Terry Casey]

Actually, your cable may not be as good as you think as, despite being

100% copper, there was a tendency to skimp on the outer shield coverage which lets in the impulsive interference that is a killer for DTV.

I have replaced my downlead with good quality coax and the aerial, which is the Belling-Lee 18 element yagi that first went on sale when BBC2 started in 1967, is in the loft, so will probably still be giving good service in another 40 years, being so well protected from the weather!

[PeterC]

No, this has loadsacopper in the screen. Five improved when I remade the bottom connection - there was quite a lot of corrosion, which wasn't expected indoors. I wondered for a start if water had been seeping down the cable, but a couple of inches in the copper was good.

That's the other thing that I must remember to check, as some firms use cheap co-ax - no way of checking what's in next door unless it's printed on the outside (she'd not be 'appy if I affected the signal by removing a connector).

[The Natural Philosopher]

Not with waving trees it aint.