Signal/aerial advice

[Isle of wight]

I live in Brading on the Isle of Wight. The IOW transmitter, Rowridge, is the other side of a hill and therefore we need a repeater which doesn't do Freeview. I've fitted a log periodic aerial with a 16db mast top booster pointing towards Rowridge and can pick up 63 Freeview channels (no ch 5) with varying degrees of success. BBC channels sit at about 40% with no bit error whereas ITV is only 30% with between 3 and 4 bit error and the occasional picture break up. What is strange though is analogue. BBC 2, ITV and Ch 4 are very acceptable but I can't get a BBC1 picture at all with break up on the sound. I've played around with direction and it's at it's optimum. I didn't want a huge aerial hence the periodic. Perhaps that huge aerial is the only option?? Any help would be gratefuly received.

 

[SamRadford]

Rowridge requires a Group A aerial for Freeview and, while a log-periodic is often a good choice - especially where interference from other transmitters is a problem - it's not necessarily the best for you.

It's quite possible that the massive analogue signal from Brading is causing your problem. I would recommend a Group A pass filter like the one listed here:
http://www.satcure.com/accs/page11c.htm#diplex

That should be fitted before* the amplifier and will cut out most of the (Group B) signal from Brading. It should then be easier for you to optimise your setup to get all multiplexes reliably.

* If the filter is fitted after the amplifier, it won't prevent amplifier overload, but it's worth a try first of all.

Note: in circumstances such as this, the *height* of the aerial can be critical. It may need to be moved down the mast a few inches at a time to find the optimum position.

I think this should fix your problem but, if it doesn't, then a Group A aerial (Blake DMX10A) might do the job. But I'd try this as a last resort.

You might also like to read the aerial story linked here:
http://www.satcure.co.uk/reviews/review103.htm#02

 

[Isle of wight]

Thanks Sam.......a couple of things. The Brading repeater is a pretty weak affair and a mast top booster is necessary. Having said that the aerial to Rowridge is 180degrees to the Brading one. My aerial's amp is in-built to the aerial and it will be difficult to fit a pass filter but I'm sure at a push it could be done. It's interesting what you say about coming down the pole as I increased the height of the aerial and my signal actually got worse.

 

[Chris Muriel]

The 180º performance will depend on the front-to-back ratio of the aerial (which should be specified).

Chirs Muriel, Manchester