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Whistling Labgear DA



 
 
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  #1  
Old February 9th 19, 07:52 PM posted to uk.tech.digital-tv
Mark Carver
external usenet poster
 
Posts: 6,422
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, 09:14 PM posted to uk.tech.digital-tv
Woody[_4_]
external usenet poster
 
Posts: 2,021
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, 12:48 AM posted to uk.tech.digital-tv
Indy Jess John
external usenet poster
 
Posts: 1,496
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
  #4  
Old February 10th 19, 03:18 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 3,270
Default Whistling Labgear DA

On 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 haven't heard any other complaints, so hopefully it's a one-off. So
send it back. But first I'd ask the complaining bat to double check it's
the amp making the noise. Put a pillow or a hand over it and see if the
noise is attenuated. Try switching it on and off. In a new flat there
could be other unfamiliar sources of weird sounds.

Bill

  #5  
Old February 10th 19, 03:36 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 3,270
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
  #6  
Old February 10th 19, 10:54 AM posted to uk.tech.digital-tv
Mark Carver
external usenet poster
 
Posts: 6,422
Default Whistling Labgear DA

On 10/02/2019 02:18, Bill Wright wrote:


I haven't heard any other complaints, so hopefully it's a one-off. So
send it back. But first I'd ask the complaining bat to double check it's
the amp making the noise. Put a pillow or a hand over it and see if the
noise is attenuated. Try switching it on and off. In a new flat there
could be other unfamiliar sources of weird sounds.


Oh, it's definitely the amp making the noise, no doubt about that.
If I get really close I can sort of hear other noises heterodyning
with it, difficult to describe.

He's 30 this year, and has spent the last 12-14 years in night clubs
etc, so I'm frankly amazed he can hear anything ! His girlfiend also
can hear it BTW.

--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #7  
Old February 10th 19, 11:29 AM posted to uk.tech.digital-tv
Brian Gaff
external usenet poster
 
Posts: 7,586
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

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"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



  #8  
Old February 10th 19, 11:38 AM posted to uk.tech.digital-tv
Mark Carver
external usenet poster
 
Posts: 6,422
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.
  #9  
Old February 10th 19, 11:38 AM posted to uk.tech.digital-tv
Brian Gaff
external usenet poster
 
Posts: 7,586
Default Whistling Labgear DA

I'd have thought that they should have returned the vdu. I remember some ICL
ones being sent back for this very problem. They obviously knew about it but
were trying to work the dodgy ones back to companies back in the 80s cos
they could not actually fix them.

Often when I was young it was more of a pressure than a sound that you could
kind of hear.

There are some vehicles around just now whose brakes still do this but I
imagine as I'm older the actual frequency is below 20 khz. No I do not mean
London Taxis!
These are VWs.

I remember my first stereo tuner. It did not have an mpx filter and when on
a stereo station I could hear a low level tone. Recording this on the three
speed tape recorder soon solved it as at half speed there was a not very
clean 9khz almost triangular wave signal at quite a high level. I was
always under the impression that this pilot tone was very low level, but
maybe the decoder was giving a rising response at hf.

Still a filter stopped it but I did notice some tendency toward making the
tuner sound kind of leaden. Nowadays of course the signal processing used
would mask that.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Indy Jess John" wrote in message
...
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



  #10  
Old February 10th 19, 11:44 AM posted to uk.tech.digital-tv
Brian Gaff
external usenet poster
 
Posts: 7,586
Default Whistling Labgear DA

Yes that pressure effect and the intermediation is what I hear. I think my
hearing was damaged in the 80s when I got too close to a couple of lightning
strikes. I now have some tinnitus which is very much like a dodgy psu or
line timbase with rattling core!
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Bill Wright" wrote in message
...
On 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 haven't heard any other complaints, so hopefully it's a one-off. So send
it back. But first I'd ask the complaining bat to double check it's the
amp making the noise. Put a pillow or a hand over it and see if the noise
is attenuated. Try switching it on and off. In a new flat there could be
other unfamiliar sources of weird sounds.

Bill



 




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