2004-06-26 11:59:19 UTC
Antiference TC18B for Rosemarkie which is approx. 23 km away.
Antiference TC18CD for Mounteagle at a distance of approx. 10km
Both transmitters are on a similar bearing from my location (I would guess
no more than 5 degrees)
Two cable runs of CT100 (approx. 10-15m long) feed into an Antiference 5153
diplexer by the TV, with a short run of CT100 to my first VCR. The signal
loops through this into the second VCR, again looping through to my third
VCR, then loopthrough and into the TV - hardly ideal, but it has been like
this since I installed the antennas approx. 20 months ago. All RF leads are
home-made using CT 100.
While my reception was not perfect, it was quite good until earlier this
year (approx. sometime in February) when, one day, reception from Rosemarkie
'took a dive' (nosier & 'ghostier' - Mounteagle is still fine). All TVs are
affected even though my main antennas feed my main TV only; all portable TVs
use individual set-top antennas. I inspected my main antennas, and apart
from the gaffa tape beginning to peel (this covers the main seal which is of
self-amalgamating tape) everything appears normal.
Reception varies, but even at its best, reception does not seem to have
returned to 'normal', and at its worst, pictures are noisy/grainy and
'ghosty', but still full colour, with stereo sound.
My neighbour also reports reception problems.
There is a line of trees approx. 250m in front of my house, the right hand
edge of which appears to be just, and no more, obscuring the line to the
transmitters - from my location, Rosemarkie is to the left of Mounteagle,
hence more likely to be obscured. As an experiment, I tried a Triax Unix 52W
at the opposite end on my house, the line from which clears the trees and
gives clear line of sight to Mounteagle and, I think, Rosemarkie (using
binoculars I think I can see the top of Rosemarkie 'peeking' out above the
top of the Black Isle). The cable run required was considerably longer (say
30m) but, if anything, Five was even better than it is with my existing
TC18CD; unfortunately, 1-4 from Rosemarkie was marginally worse.
I contacted the BBC on a number of occasions and, eventually, someone took
test measurements in the village (not at my location however - Am I
incorrect in thinking that measurements from anywhere other then the exact
problem location are largely worthless?) and reported field strengths as:-
'just under or nudging 80dBuV/m'
Can I assume that, for whatever reason, signal from Rosemarkie is weaker at
my location than it used to be, and should consider a single stage masthead
amp? Do I have to get some signal strength measurements from my antenna feed
before attempting any solutions (I'm not sure if any of the local installers
are any good, and I don't have a signal strength meter).
I don't know if DTT is any good at my location, but I would prefer to have
analogue for my 'prodigious' timeshifting requirements (not to mention, I'm
led to believe, the proliferation of annoying DOGs, and less than ideal
bitrates etc. on digital). I am in the process of buying a new TV as my main
set 'died' recently, so an IDTV is a possibility.
Any other suggestion re the reception problems, as well as the correct way
to feed three VCRs and one TV (located together) from a single antenna feed,
would be much appreciated.
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