Low Noise UHF Pre-amp, Advice Please.

Can anyone recommend a commercially available very low noise UHF Pre-amp,
for amplifying a marginal DTT signal?

I have a friend in Derby, using Freeview (Sutton Coldfield TX) from a newly
installed communal aerial. MUXs 1, 2, A, B & C are all showing "Good" signal
strength, but MUX D (ch55) hardly shows any signal at all. Freeview STB
refuses to load channels.

I'm not in the trade, so don't have any gear to test S/N levels etc. I'm
wondering if the installed aerial may be a Group B (I can't tell by looking
at it), and therefore ch55 is just out of band. Also Derby city centre (DE1)
is not the best place for DTT reception.

Chris.

Chris wrote:
Can anyone recommend a commercially available very low noise UHF Pre-amp,
for amplifying a marginal DTT signal?

I have a friend in Derby, using Freeview (Sutton Coldfield TX) from a newly
installed communal aerial. MUXs 1, 2, A, B & C are all showing "Good" signal
strength, but MUX D (ch55) hardly shows any signal at all.

A preamp after the outlet from a distribution won't help much, if at
all. You need to get the installer of the system back to sort this
problem out, or at least to explain why Mux D can't be provided.

Do other users of the system have the same problem?

Also Derby city centre (DE1) is not the best place for DTT reception.

What does the postcode checker at http://www.digitaluk.co.uk/ tell you?
Enter a full address and tick the 'I'm in the trade' box.

--
Andy

"Chris" wrote in message
.uk...
Can anyone recommend a commercially available very low noise UHF
Pre-amp, for amplifying a marginal DTT signal?

I have a friend in Derby, using Freeview (Sutton Coldfield TX) from a
newly installed communal aerial. MUXs 1, 2, A, B & C are all showing
"Good" signal strength, but MUX D (ch55) hardly shows any signal at
all. Freeview STB refuses to load channels.

I'm not in the trade, so don't have any gear to test S/N levels etc.
I'm wondering if the installed aerial may be a Group B (I can't tell
by looking at it), and therefore ch55 is just out of band. Also Derby
city centre (DE1) is not the best place for DTT reception.

Chris.







I would have thought Waltham should be the site for Derby - especially
as it transmits E Midlands opt-outs?


--
Woody

harrogate three at ntlworld dot com

"Woody" wrote in message
...
"Chris" wrote in message
.uk...
Can anyone recommend a commercially available very low noise UHF Pre-amp,
for amplifying a marginal DTT signal?

I have a friend in Derby, using Freeview (Sutton Coldfield TX) from a
newly installed communal aerial. MUXs 1, 2, A, B & C are all showing
"Good" signal strength, but MUX D (ch55) hardly shows any signal at all.
Freeview STB refuses to load channels.

I'm not in the trade, so don't have any gear to test S/N levels etc. I'm
wondering if the installed aerial may be a Group B (I can't tell by
looking at it), and therefore ch55 is just out of band. Also Derby city
centre (DE1) is not the best place for DTT reception.

Chris.







I would have thought Waltham should be the site for Derby - especially as
it transmits E Midlands opt-outs?

There's large areas in and around Derby where Waltham don't work, hence the
little tx that provides Central E on the outskirts of the city.

Anyway, the OP wants to forget 'commercially available very low noise UHF
preamps' and install the correct aerial. Gp B aerials are really crap on
ch55 (all yagis are really crap just above their design range). If a Gp E
won't do it I'd use a Gp CD with a separate masthead amp and a single
channel combiner. If it's a decent communal system it will have
filter/levellers anyway.

I assume that the plan is to fit the amp at the masthead. You aren't
proposing some sort of set-back thing are you?

You could do worse that try different aerial locations as well, and consider
other Txs.

Bill

I would have thought Waltham should be the site for Derby - especially as
it transmits E Midlands opt-outs?

There's large areas in and around Derby where Waltham don't work, hence
the little tx that provides Central E on the outskirts of the city.

Anyway, the OP wants to forget 'commercially available very low noise UHF
preamps' and install the correct aerial. Gp B aerials are really crap on
ch55 (all yagis are really crap just above their design range). If a Gp E
won't do it I'd use a Gp CD with a separate masthead amp and a single
channel combiner. If it's a decent communal system it will have
filter/levellers anyway.

I assume that the plan is to fit the amp at the masthead. You aren't
proposing some sort of set-back thing are you?

You could do worse that try different aerial locations as well, and
consider other Txs.

Bill


Hi Guys, and thanks for your advice.

To be honest, the reception of MUX D at my friend's location in Derby is
more of a curiosity for me, than it is a necessity for him. Reception of
Waltham is out of the question in his neck of the woods (although it would
seem the obvious TX for Derby, if you didn't know the local area).
I'm afraid of heights, so no way will I be climbing onto the roof to tweek
the aerial! It's an 18 element yagi, with a large reflector (sorry I didn't
take a picture of it), followed by a masthead pre-amp. I don't know what
happens after that, pror to reaching the wall socket. Looks as though it
supplies about 10 flats. MUXs 1 to C show "good" signal strength (on the
STB) all analogue channels are noise-free. Postcode checker says DTT not
available, so I guess he's lucky to get anything on Freeview.

Chris.

Hmm, this won't work if at the back of the set because.
It will amplify the noise in the distribution system, thus making the noise
louder, (so to speak) as well.
It will probably overload with some signals and shove spurious signals all
over the place making things far worse than they are already!

Sounds like someone needs to find out from the other residents if they all
have problems with the same channels, if so, then there is a good case to
get the installer back to do the installation properly. I'd suggest a second
aerial if indeed the problem is where you are, but it may be better to fit
the right one in the first place!

Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________


"Chris" wrote in message
.uk...
Can anyone recommend a commercially available very low noise UHF Pre-amp,
for amplifying a marginal DTT signal?

I have a friend in Derby, using Freeview (Sutton Coldfield TX) from a
newly installed communal aerial. MUXs 1, 2, A, B & C are all showing
"Good" signal strength, but MUX D (ch55) hardly shows any signal at all.
Freeview STB refuses to load channels.

I'm not in the trade, so don't have any gear to test S/N levels etc. I'm
wondering if the installed aerial may be a Group B (I can't tell by
looking at it), and therefore ch55 is just out of band. Also Derby city
centre (DE1) is not the best place for DTT reception.

Chris.

hBrian Gaff wrote:
Hmm, this won't work if at the back of the set because.
It will amplify the noise in the distribution system, thus making the
noise louder, (so to speak) as well.

That's assuming it has any gain to begin with? I just measured the signal
strength of Mux1 on Ch 41 on a Pioneer STB with and without a Masterplug
wall-mounted UHF booster in circuit. With booster 75% signal strength,
without booster 75% strength. No change in signal quality which was 100% in
both cases. A Labgear booster/splitter didn't show any measurable gain
either.

(kim)

kim wrote:

That's assuming it has any gain to begin with? I just measured the signal
strength of Mux1 on Ch 41 on a Pioneer STB with and without a Masterplug
wall-mounted UHF booster in circuit. With booster 75% signal strength,
without booster 75% strength. No change in signal quality which was 100% in
both cases. A Labgear booster/splitter didn't show any measurable gain
either.

I think that's telling you more about the signal strength display on the
STB than about the amplifiers. Try attenuating the signal without an
amplifier until the strength and quality both show a noticeable fall.
You might need to insert 12, 18 or more dB to achieve this.

Then insert an amplifier after the attenuator - I'd expect you to see an
increase in strength but little or no increase in quality. Then put the
amplifier ahead of the attenuator and the quality should jump back close
to "100%".

--
Andy

Andy Wade wrote:
kim wrote:

That's assuming it has any gain to begin with? I just measured the
signal strength of Mux1 on Ch 41 on a Pioneer STB with and without a
Masterplug wall-mounted UHF booster in circuit. With booster 75%
signal strength, without booster 75% strength. No change in signal
quality which was 100% in both cases. A Labgear booster/splitter
didn't show any measurable gain either.

I think that's telling you more about the signal strength display on
the STB than about the amplifiers. Try attenuating the signal
without an amplifier until the strength and quality both show a
noticeable fall. You might need to insert 12, 18 or more dB to
achieve this.
Then insert an amplifier after the attenuator - I'd expect you to see
an increase in strength but little or no increase in quality. Then
put the amplifier ahead of the attenuator and the quality should jump
back close to "100%".

I have a masthead amp as well. When that is inserted in exactly the same
place as the room boosters there is a significant improvement in signal
strength as measured by the STB.

(kim)