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Whistling Labgear DA



 
 
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  #1  
Old February 9th 19, 06:52 PM posted to uk.tech.digital-tv
Mark Carver
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Posts: 6,528
Default Whistling Labgear DA

I bought this for our lad's flat, and installed it just before
Christmas. Does the job fine, so I switched it off and forgot all about it.

Yesterday he (finally !) moved in, and switched it on. He tells me
there's a penetrating high pitched whistle from it. Neither myself
nor Mrs Carver can hear anything. I assume it's the SMPSU making the
racket. Do they all do that, designed to go in the loft to keep bats
away (or attract them, I'm not sure how it works ?) Or am I (well he)
unlucky, (his is installed behind the sofa in the living room) and I'll
just throw it back at CPC and get another one?

https://cpc.farnell.com/labgear/lda102r/booster-2-output-4g-filtered-red/dp/AP03298?ost=ap03298&ddkey=https%3Aen-CPC%2FCPC_United_Kingdom%2Fsearch




--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #2  
Old February 9th 19, 08:14 PM posted to uk.tech.digital-tv
Woody[_4_]
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Posts: 2,087
Default Whistling Labgear DA

On Sat 09/02/2019 18:52, Mark Carver wrote:
¬*I bought this for our lad's flat, and installed it just before
Christmas. Does the job fine, so I switched it off and forgot all about it.

Yesterday he (finally !) moved in, and switched it on. He tells me
there's a penetrating high pitched whistle from it. Neither myself
nor Mrs Carver can hear anything. I assume it's the SMPSU making the
racket. Do they all do that, designed to go in the loft to keep bats
away (or attract them, I'm not sure how it works ?) Or am I (well he)
unlucky, (his is installed behind the sofa in the living room) and I'll
just throw it back at CPC and get another one?

https://cpc.farnell.com/labgear/lda102r/booster-2-output-4g-filtered-red/dp/AP03298?ost=ap03298&ddkey=https%3Aen-CPC%2FCPC_United_Kingdom%2Fsearch




I've got one of them - well the single output version - and yes they do
have a switched mode PSU in them but it should be running at a frequency
far above hearing range even to a youngster.

How do I know? Because mine too was in the loft (silent AFAIK) and it
was radiating an amazing amount of rubbish across the HF bands - it
increased the noise floor on my receiver by 6db!!

If you want one with a linear supply look at the ProCeption range which
are stocked by both CPC and Toolstation.

Alternatively get one that has an external PSU or the facility for one
and get a linear wall wart - they are heavier and get warm (which should
help son and heir keep the chill away!

--
Woody

harrogate three at ntlworld dot com
  #3  
Old February 10th 19, 10:29 AM posted to uk.tech.digital-tv
Brian Gaff
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Posts: 7,823
Default Whistling Labgear DA

I can only agree. The daft thing is you can make switch mode supplies that
do not radiate crap, and looking inside some it seems mainly only to be a
slightly larger transformer and a few capacitors extra in them. One wonders
why they have to make crap ones. Its all one supposes in the design of a
transformer that does not saturate and some hf removal filters.
Re the sound. Well I had one here that used to sing. You had to give it a
little tape. Sub harmonics or something I would imagine.
The most annoying one was the invertors in the screen of a dell laptop. we
eventually stopped it by wedging some folded toilet paper against it as you
closed the screen surround.
No rude comments please.
Brian

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"Woody" wrote in message
...
On Sat 09/02/2019 18:52, Mark Carver wrote:
I bought this for our lad's flat, and installed it just before
Christmas. Does the job fine, so I switched it off and forgot all about
it.

Yesterday he (finally !) moved in, and switched it on. He tells me
there's a penetrating high pitched whistle from it. Neither myself
nor Mrs Carver can hear anything. I assume it's the SMPSU making the
racket. Do they all do that, designed to go in the loft to keep bats away
(or attract them, I'm not sure how it works ?) Or am I (well he) unlucky,
(his is installed behind the sofa in the living room) and I'll just throw
it back at CPC and get another one?

https://cpc.farnell.com/labgear/lda102r/booster-2-output-4g-filtered-red/dp/AP03298?ost=ap03298&ddkey=https%3Aen-CPC%2FCPC_United_Kingdom%2Fsearch

I've got one of them - well the single output version - and yes they do
have a switched mode PSU in them but it should be running at a frequency
far above hearing range even to a youngster.

How do I know? Because mine too was in the loft (silent AFAIK) and it was
radiating an amazing amount of rubbish across the HF bands - it increased
the noise floor on my receiver by 6db!!

If you want one with a linear supply look at the ProCeption range which
are stocked by both CPC and Toolstation.

Alternatively get one that has an external PSU or the facility for one and
get a linear wall wart - they are heavier and get warm (which should help
son and heir keep the chill away!

--
Woody

harrogate three at ntlworld dot com



  #4  
Old February 10th 19, 10:38 AM posted to uk.tech.digital-tv
Mark Carver
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Posts: 6,528
Default Whistling Labgear DA

On 09/02/2019 20:14, Woody wrote:
On Sat 09/02/2019 18:52, Mark Carver wrote:


I've got one of them - well the single output version - and yes they do
have a switched mode PSU in them but it should be running at a frequency
far above hearing range even to a youngster.

How do I know? Because mine too was in the loft (silent AFAIK) and it
was radiating an amazing amount of rubbish across the HF bands¬* - it
increased the noise floor on my receiver by 6db!!

If you want one with a linear supply look at the ProCeption range which
are stocked by both CPC and Toolstation.


ProCeption was my first choice, but they don't seem to have 800 MHz LPF
and they are Belling Lee rather than F-Type sockets ?

https://www.easyflip.co.uk/CPC_Catalogue/?page=159

Alternatively get one that has an external PSU or the facility for one
and get a linear wall wart - they are heavier and get warm (which should
help son and heir keep the chill away!


I like your thinking Woody ;-)

I've dug out an old 1x2 Wolsey I'd forgotten I had, so swap that in,
while I sort out the replacement



--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #5  
Old February 10th 19, 12:55 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 3,576
Default Whistling Labgear DA

On 10/02/2019 10:38, Mark Carver wrote:

I've dug out an old 1x2 Wolsey I'd forgotten I had, so swap that in,
while I sort out the replacement


Is an amplifier necessary? I suspect from other correspondence that in
this case it is, but in general many installations have amps that could
be replaced with a splitter. DTT has made this possible in many cases.

Bill

  #6  
Old February 10th 19, 03:02 PM posted to uk.tech.digital-tv
Mark Carver
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Posts: 6,528
Default Whistling Labgear DA

On 10/02/2019 12:55, Bill Wright wrote:
On 10/02/2019 10:38, Mark Carver wrote:

I've dug out an old 1x2 Wolsey I'd forgotten I had, so swap that in,
while I sort out the replacement


Is an amplifier necessary? I suspect from other correspondence that in
this case it is, but in general many installations have amps that could
be replaced with a splitter. DTT has made this possible in many cases.


The muxes were pretty poor summertime (well Sept) about 40-45 dBuV owing
to a thick wood the aerial looks through, at present they are 10ish dB
better than that. It's a 15 metre run to his bedroom from the point the
aerial feeder enters the property, (which only has 6ft or so of feeder
to the aerial, so in effect it's acting as a masthead amp.)

I'm getting about 30dB CNR at the bedrooom, and the muxes look awful
(ragged and uneven) on an analyzer, but the telly reports 90/90 on the
silly bargraph thing.

Anyway, DTT is of secondary importance, as one of his employment perks
is a free Sky Q multiroom system, and the path to Astra is totally clear
of any obstructions, or future obstructions.

--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #7  
Old February 10th 19, 04:16 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 3,576
Default Whistling Labgear DA

On 10/02/2019 15:02, Mark Carver wrote:

The muxes were pretty poor summertime (well Sept) about 40-45 dBuV owing
to a thick wood the aerial looks through, at present they are 10ish dB
better than that. It's a 15 metre run to his bedroom from the point the
aerial¬* feeder enters the property, (which only has 6ft or so of feeder
to the aerial, so in effect it's acting as a masthead amp.)

I'm getting about 30dB CNR at the bedrooom, and the muxes look awful
(ragged and uneven) on an analyzer, but the telly reports 90/90 on the
silly bargraph thing.

Deffo needs an amp!

Bill

  #8  
Old February 9th 19, 11:48 PM posted to uk.tech.digital-tv
Indy Jess John
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Posts: 1,620
Default Whistling Labgear DA

On 09/02/2019 18:52, Mark Carver wrote:

Yesterday he (finally !) moved in, and switched it on. He tells me
there's a penetrating high pitched whistle from it. Neither myself
nor Mrs Carver can hear anything.


Although most people can't hear a very high pitched whistle, and the
standard assumption was that 20,000Hz was the limit of clear hearing in
the young, and 22,000Hz is about the limit of audibility, there are some
that can hear even higher frequencies. Your lad might be one of them.

In the very early days of VDU being installed in offices where I was
working at the time, one young girl complained that the newly installed
VDU two desks away was making so much noise that she was distracted by
it and she went home some days with a headache. Nobody else could hear
a thing. The office manager borrowed a meter, and sure enough the VDU
was making a lot of noise at around 26,000Hz. Then he took the girl to
a different office with a VDU, and she could hear that one too.
Eventually after a bit of managerial chat about options the girl was
persuaded to take a different post in a room that was not scheduled to
get a VDU. She was happy there.

Jim
  #9  
Old February 10th 19, 02:36 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 3,576
Default Whistling Labgear DA

On 09/02/2019 23:48, Indy Jess John wrote:

In the very early days of VDU being installed in offices where I was
working at the time, one young girl complained that the newly installed
VDU two desks away was making so much noise that she was distracted by
it and she went home some days with a headache.¬* Nobody else could hear
a thing.¬* The office manager borrowed a meter, and sure enough the VDU
was making a lot of noise at around 26,000Hz.¬* Then he took the girl to
a different office with a VDU, and she could hear that one too.
Eventually after a bit of managerial chat about options the girl was
persuaded to take a different post in a room that was not scheduled to
get a VDU.¬* She was happy there.


For a complete contrast, when my dad set off his burglar alarm by
accident (a frequent occurrence) he was always unaware of the piercing
two tone internal sounder and would sit reading until a neighbour came
in to see what the hell was going on. One day I stood him right next to
the sounder (where the noise was almost unbearable) and asked him what
he could hear. He said he could hear a ticking. I said, "Say 'tick' when
it ticks." He said 'tick' in time with the change from one tone to the
other. He could hear a low note, inaudible to us because of the loudness
of the tones, that happened each time the tones swapped. He couldn't
hear the tones, both of which were high pitched. He had absolutely no HF
hearing, yet he could hear LF very well. His hearing had been damaged by
explosions in the war.

Bill
  #10  
Old February 10th 19, 11:22 AM posted to uk.tech.digital-tv
Andy Burns[_12_]
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Posts: 951
Default Whistling Labgear DA

Bill Wright wrote:

I stood him right next to the sounder (where the noise was almost
unbearable) and asked him what he could hear. He said he could hear a
ticking. I said, "Say 'tick' when it ticks." He said 'tick' in time with
the change from one tone to the other. He could hear a low note,
inaudible to us because of the loudness of the tones, that happened each
time the tones swapped.


When filing past those sounders during fire drills or accidental alarms,
you can feel the resonance change in your skull, a bit like the (bone
conductance?) noise you hear when you scrunch on/off all the muscles
around your forehead/jaw/ears
 




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