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#11
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On 07/10/2018 12:26, Jeff Layman wrote:
On 07/10/18 09:58, Jeff Layman wrote: I'll go up in the loft soon and play around a bit with the position of the aerial. Ten minutes in the loft and I am amazed at the difference a few inches can make (no smut, please...). There seemed to be absolutely no logic where to try the aerial (NB no amp used). I could go from a signal quality of 1 or 2 and a very intermittent picture to a steady 9 with barely 6 inches movement. I found it didn't matter where the aerial was - I tried it high up just under a fluorescent light and 3 feet below it resting on a cardboard box. Both gave a quality of 9 or 10, yet in between the signal was lost almost entirely. In the end, for simplicity, I simply lowered the aerial about 8 inches on the original mount. That gave a quality of around 7 on Ch55 and 8 or 9 on 56. Strangely, in that position it was pointing through breeze blocks rather than the tiles, and from what I'd read I had expected that to give a poorer signal than through tiles. Standing waves Bill |
#13
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On 07/10/18 23:14, Bill Wright wrote:
On 07/10/2018 09:58, Jeff Layman wrote: Yes, Rowridge is received across The Solent. Also, it was very wet yesterday with a good bit of rain all day. However, this morning it is dry and sunny. Despite that, about 10 minutes ago I was getting "No service" onÂ* Ch55 and 56. But now there is no problem - good picture on all Com7/8 channels. Signal strength is steady at 9, with signal quality 6 - 8. How can it vary so much over a few minutes? NB all this is without a masthead amp connected. I'll go up in the loft soon and play around a bit with the position of the aerial. There is a lot of good info at http://aerialsandtv.com/loftaerials.html#AttenuationLevelsThroughRoofs on how changing position just a foot or two can affect reception markedly. There's even better info he http://www.wrightsaerials.tv/article...sat-201007.pdf Very informative. But it seems that with the move of Com7/8 when they were on Group A frequencies to Ch55 and 56 seems to suggest that unless you're going to use a Group A and separate Group C/D aerial, you are more-or-less stuck with a log-periodic. And, as I've found out, it's those damn high frequencies which seem to cause most problems when you are trying to find that "sweet spot" in the loft. I'm also waiting to see what happens to reception when we get a day of heavy rain. One thing I'd add to watch out for today is solar panels. The previous owner of this place seemed to like experimenting, and we have a couple of (disconnected) thermal solar panels very near to where the aerial is. I think they have been there since the late 80s. Maybe they are interfering a bit, but short of moving the aerial away completely, I'll never know. Failing any improvement there I'll try the amp again, as an outside aerial isn't an option. That will reduce outage times and durations but might not eliminate them. Masthead amps can't do magic. Couldn't agree more. Bill -- Jeff |
#14
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On 07/10/18 20:56, Ian Jackson wrote:
In message , Jeff Layman Lofts are often full of reflections. These create loads of frequency dependent peaks and nulls in the RF field. Moving an aerial only slightly can produce a great change of signal strength from channel to channel - and this can be particularly marked if is high gain (and hence highly directional). A low-gain aerial is often less-critical about where you place it. About a week on and until today the reception was excellent. But with the heavy rain this morning Ch55 was way down on signal quality again (0 - 3) with pixelation and sometimes a blank screen. But Ch56 was still coming through fine (quality 7). I still find it hard to understand why there is so much difference between adjacent channels on 746MHz and 754MHz, but there obviously is. -- Jeff |
#15
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Jeff Layman wrote:
I still find it hard to understand why there is so much difference between adjacent channels on 746MHz and 754MHz Different radiation patterns to accommodate continental transmitters? |
#16
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On 14/10/18 12:05, Andy Burns wrote:
Jeff Layman wrote: I still find it hard to understand why there is so much difference between adjacent channels on 746MHz and 754MHz Different radiation patterns to accommodate continental transmitters? Dunno. How would you find out? I've been searching the internet for Rowridge radiation patterns but haven't come up with anything useful. Maybe Mark C knows something about the Com 7/8 antennas "halfway up the pole" at Rowridge. -- Jeff |
#17
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Jeff Layman wrote:
Andy Burns wrote: Different radiation patterns to accommodate continental transmitters? Dunno.Â* How would you find out? http://s1211.photobucket.com/user/MikeDimmickTx/library/Radiation%20Patterns/Meridian/Rowridge%20group?sort=3&page=1 Not sure if they're Carver-approved though (the ukfree.tv ones probably aren't) |
#18
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Andy Burns wrote:
http://s1211.photobucket.com/user/MikeDimmickTx/library/Radiation%20Patterns/Meridian/Rowridge%20group?sort=3&page=1 Oops they're DAB, not DTT |
#19
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On 14/10/18 13:47, Andy Burns wrote:
Andy Burns wrote: http://s1211.photobucket.com/user/MikeDimmickTx/library/Radiation%20Patterns/Meridian/Rowridge%20group?sort=3&page=1 Oops they're DAB, not DTT Never mind. Thanks for trying. I searched on the tx.mb21.co.uk for anything to do with Rowridge in the last year. Google found some hits, but as far as I can see they didn't have anything to do with Rowridge. -- Jeff |
#20
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Jeff Layman wrote:
Andy Burns wrote: http://s1211.photobucket.com/user/MikeDimmickTx/library/Radiation%20Patterns/Meridian/Rowridge%20group?sort=3&page=1 Oops they're DAB, not DTT Never mind. Thanks for trying. Actually they seem to be a mish-mash of DTT, DAB and FM, but photobucket isn't an ideal indexing system ... |
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