In article , Jim Lesurf jcgl@st-
and.demon.co.uk writes
In article , tony sayer

wrote:
In article , Jim Lesurf jcgl@st-
and.demon.co.uk writes
[snip]

Presume you do have a directional aerial and a good grade, CT100 or
similar, of co-ax feeder?.

I use three different loft dipoles for the three different FM tuners in
daily use. They typically give around 600-800 microV at their downlead
ends. The cables vary but are all either CT100 or an equivalent in terms of
performance from the days before the term CT100 was used (so far as I
recall.) The cable runs are only about 3-4 metres in each case, and are
continuous from antenna to the plug in the RX socket.

FWIW yesterday I lugged the CT7000 around and checked the levels on each
antenna output. So the above are correct assuming the (old) calibration
for the tuner is OK.

Course your local TX might be re-transmiting what it receives if its an
RBR one 'tho if a main station it should be on PCM, and its very
possible that the BBC don't even know if theres a problem.

Which one was it again Jim?.

Forfar. I can't recall the ERP, but I think it isn't one of the higher
powers. However it gives higher levels here than the alternatives. The
problem I think is that although we are up a hill, the main parts of Fife
'behind' us are higher and tend to block signals from inland. We might get
more from the other transmitters if the topology were favourable. Alas,
Fife isn't the Fens... :-/

Yes its a main station and PCM fed at 17Kw mixed pol...

Perhaps a bit more directionality on the receiving aerials?. You might
be having some multipath perhaps...

http://tx.mb21.co.uk/gallery/forfar.asp



TBH Having started thinking about this again I am starting to wonder if the
real problem is the CT7000. Although an excellent design, it is now
reaching its 30th birthday, and it suffers from poor internal contacts due
to the widespread use of tiny 'pin-socket' connectors between the internal
modules. It is about time I tried something else for the main hifi system.
Now I've started thinking about this, I haven't noticed so much in the way
of problems even on a Quad FM4 which - in principle - has nothing like as
good an RF performance as the CT7000...

Yes I had one for a short while once that was owned by Phil Swift of
Audiolab and that was a bit dodgy then and that was in the early 80's so
time wouldn't have helped;!..


It was IIRC a good RF performer and in comparison the FM 4 wasn't
anything that wonderful.


I noticed in a review in a recent mag that one tuner (Creek IIRC) reached
70dB SNR full-quieting with 400microV in, whereas the CT7000 needs about
800 microV for this.

They 'umble old Denon TU260 MK2 is remarkably good RF and otherwise.

I'd look around for a second-hand Audiolab T8000 on e-bay thats about as
good as an FM tuner gets or needs to be;!..


IIRC Angus Mckenzie, although enthusiastic about the
CT7000 thought that the front end gain/noise figure wasn't as good as
it could be, even years ago, but loved it for the excellent selectivity
and low distortion, etc.

The interference tends to go un-noticed with something like a string
quartet or piano recital, but can show up on proms.

Why do you think that then?..

Alas, the level
compression on FM I now find more noticable than some years ago.
partly due to it being more severe, partly I guess due to becoming
accustomed to other sources that don't have it. Thus in practice,
with orchestral music it is the level compression I find distracting
more often these days. DAB was much better in this respect.

Six of one and half a dozen of the other;(...


One of the things I welcomed about DAB as it has shown almost zero
interference effects here. Signal level about 12dB above the top of the
scale on the tuner.

Well thats what it was supposed to do eh?. I just wish they'd admit
T-DAB is bu**ered as a serious medium, and really do some upping of the
bit rates in Satellite!..



It does suffer from co channel as some on the south coast will tell you
'jus cos its dab doesn't mean its not interfereable with!...

I'd agree. However here it has shown no particular signs of the sound being
interfered with by anyone - apart from the BBC themselves! :-/

Quite....

Slainte,

Jim


--
Tony Sayer