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Tinfoil madness

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dylan at deedums

Nov 3, 2009, 4:56 PM

Post #1 of 10 (541 views)
Permalink

Tinfoil madness

Let me begin with the mad picture, then explain how I got there (see
attached).

The only way I can get reliable reception with the TVNZ and Mediaworks
transponders is to wrap my USB sticks with tinfoil and ensure that
tinfoil is connected to the casing of the RF splitter. The tinfoil can't
cover the fly leads from the USB sticks, and it can't contact with the
shield of the USB connector.

Let me start from the beginning....

I decided to have a go with DVB-T for freeview. I got a pair of USB
sticks. I didn't want them in the lounge where I have existing RF
outlets so I installed a splitter in the basement and added 23m [1] of
good Quad shield RG6 cable to extend the aerial connections into my
computer room at the other end of the house.

This almost worked. I had good TVNZ and Mediaworks, but the Kordia
transponder was breaking up, regular blocking etc.

I had a play with tzap to try and get an idea of what's going on.

I was getting a signal strength of 45-50%, with a low BER and no
uncorrected blocks for TVNZ and Mediaworks.
I was getting a signal strength of 35-42%, with a moderate BER and a
small number of uncorrected blocks for Kordia.

I decided it was time to audit the whole aerial/cabling/splitter setup.
The UHF aerial on the roof was small, rusty, and using the cheapest
nastiest cable. The VHF/UHF combiner was full of corrosion and a spider
colony. The cable from the combiner to the basement was a little nasty.

I replaced the UHF aerial, the combiner, the cable to the basement, and
the splitter in the basement (with a splitter with the right power pass
options should I need to add a masthead amplifier later).

At the end of this exercise the signal strength seems to have dropped
slightly, but it's now the same for all the transponders (approx 45%).

If I plug the pair of USB sticks into my laptop they both work fine, low
BER, no uncorrected blocks.

If I plug them into the backend PC it goes nuts. Sometimes they work.
Sometimes one stick works, the other fails with a high BER and lots of
bad blocks, and sometimes both sticks fail, again with high BER and lots
of bad blocks. More confusing is the failures are with the TVNZ and
Mediaworks transponders. The Kordia one is perfect.

I went through all kinds of exercises, changed the splitter, changed the
cables, added a powered usb hub, tried different usb ports on the
backend PC. At one point during the process I convinced myself the
problem was RF interference from the backend PC so started playing with
bits of tin foil. I eventually settled on the madness described at the
beginning of this email which works rather well!

Does anyone have a sane explanation for the issues I'm seeing?

I have a number of theories...

1. The signal strength is too low and it only takes the slightest bit of
interference/noise to push it below the working threshold and fail.
2. There is a nasty source of interference in/near my house.
3. Something electrical, ground loop, noisy power, etc... Laptop running
on battery is happy, PC running on mains sad. Added an online UPS to the
mix but this didn't help.

I see a number of things I can do now:

1. Make myself a hat from the left over tin foil and hope I get a moment
of clarity.
2. Accept the status quo, it is working after all, I just don't
understand why.
3. Futz with the antena setup further, mast head amp, new UHF aerial
closer to the PC, professional installer.
4. Buy a PCI/PCIe based tuner and hope it works better.

Any ideas/comments/etc greatly appreciated.

Thanks,

Dylan

[1] In case people don't know, most cables (RF, cat5/6) had printing on
the casing every meter. Somewhere buried in the writing is the number of
meters left on the reel. If you can find the writing closest to each end
of a cable you can subtract the two values and determine how long your
cable is :)

Attachments:

tinfoil_madness.JPG (52.7 KB)

dean at deanpemberton

Nov 4, 2009, 1:40 AM

Post #2 of 10 (523 views)
Permalink

Re: Tinfoil madness [In reply to]

Dylan Hall wrote:
> Let me begin with the mad picture, then explain how I got there (see
> attached).
> ...
>
> 3. Something electrical, ground loop, noisy power, etc... Laptop
> running on battery is happy, PC running on mains sad. Added an online
> UPS to the mix but this didn't help.
>
OMG =)

I know that people have had some real problems with earthing and DVB-S.
Esp when plugging electrical connections from a set top box to a PC or TV.
Googling for "DVB earthing" etc might bring you up some tips.

If the tinfoil helps then it might be providing a common earth on
everything. What happens if you remove the foil, but earth the antenna,
cable shield and the splitter?
Does it achieve the same thing as the tinfoil?

As another idea. What does your CRO tell you is going on between the
splitter housing and the PC case if you disconnect things? Got a
voltage there? Spikes?

Other than that, learn to love tinfoil =)

Dean

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jonathan.hoskin at gmail

Nov 4, 2009, 12:03 PM

Post #3 of 10 (511 views)
Permalink

Re: Tinfoil madness [In reply to]

Looks to me like the tinfoil is bringing everything up (or down) to the same
level.

Is your PC even earthed? Tried another IEC cable or even another power
point? Maybe the earth conductor has fallen out of the back of your power
point, or even worse your house earthing is dodgy. Try running a garden hose
over your outside earth peg for half an hour and see if that helps.

As already mentioned a scope or multimeter might point out something there.

Jonathan

stugo at xtra

Nov 4, 2009, 11:11 PM

Post #4 of 10 (491 views)
Permalink

Re: Tinfoil madness [In reply to]

Hi Dylan
I will throw in my two cents worth in. First I do not have any Sat gear
set up, must get round to it.
But I am a sparky so I will throw in some ideas.
As has been pointed out a multi meter with some testing info would
help, a ups even a interactive and not a double conversion type will
probably not sort out a grounding or earthing fault.
The think that leaps out is that the is no problem when isolated from
the mains, on battery. But I do have a question, does your signal
improve or do they remain the same?
If it remains the same I would try a get that up, I may be wrong but I
thought that getting it around 70% or above would me preferable.
I can give you instructions on how to test you earthing at power point
and gear to a ruff level with out spending heaps of money on special gear
but you will need at least a cheap meter.
One last thing as I do not now the area you are in, but is the actual
aerial actually the correct one for the area, A electrical supplier like
Rexel, usually will be able to check, I noticed that one I had was
different from the neighbors and was the wrong type.
Stu

Dylan Hall wrote:
> Let me begin with the mad picture, then explain how I got there (see
> attached).
>
> The only way I can get reliable reception with the TVNZ and Mediaworks
> transponders is to wrap my USB sticks with tinfoil and ensure that
> tinfoil is connected to the casing of the RF splitter. The tinfoil
> can't cover the fly leads from the USB sticks, and it can't contact
> with the shield of the USB connector.
>
> Let me start from the beginning....
>
> I decided to have a go with DVB-T for freeview. I got a pair of USB
> sticks. I didn't want them in the lounge where I have existing RF
> outlets so I installed a splitter in the basement and added 23m [1] of
> good Quad shield RG6 cable to extend the aerial connections into my
> computer room at the other end of the house.
>
> This almost worked. I had good TVNZ and Mediaworks, but the Kordia
> transponder was breaking up, regular blocking etc.
>
> I had a play with tzap to try and get an idea of what's going on.
>
> I was getting a signal strength of 45-50%, with a low BER and no
> uncorrected blocks for TVNZ and Mediaworks.
> I was getting a signal strength of 35-42%, with a moderate BER and a
> small number of uncorrected blocks for Kordia.
>
> I decided it was time to audit the whole aerial/cabling/splitter
> setup. The UHF aerial on the roof was small, rusty, and using the
> cheapest nastiest cable. The VHF/UHF combiner was full of corrosion
> and a spider colony. The cable from the combiner to the basement was a
> little nasty.
>
> I replaced the UHF aerial, the combiner, the cable to the basement,
> and the splitter in the basement (with a splitter with the right power
> pass options should I need to add a masthead amplifier later).
>
> At the end of this exercise the signal strength seems to have dropped
> slightly, but it's now the same for all the transponders (approx 45%).
>
> If I plug the pair of USB sticks into my laptop they both work fine,
> low BER, no uncorrected blocks.
>
> If I plug them into the backend PC it goes nuts. Sometimes they work.
> Sometimes one stick works, the other fails with a high BER and lots of
> bad blocks, and sometimes both sticks fail, again with high BER and
> lots of bad blocks. More confusing is the failures are with the TVNZ
> and Mediaworks transponders. The Kordia one is perfect.
>
> I went through all kinds of exercises, changed the splitter, changed
> the cables, added a powered usb hub, tried different usb ports on the
> backend PC. At one point during the process I convinced myself the
> problem was RF interference from the backend PC so started playing
> with bits of tin foil. I eventually settled on the madness described
> at the beginning of this email which works rather well!
>
> Does anyone have a sane explanation for the issues I'm seeing?
>
> I have a number of theories...
>
> 1. The signal strength is too low and it only takes the slightest bit
> of interference/noise to push it below the working threshold and fail.
> 2. There is a nasty source of interference in/near my house.
> 3. Something electrical, ground loop, noisy power, etc... Laptop
> running on battery is happy, PC running on mains sad. Added an online
> UPS to the mix but this didn't help.
>
> I see a number of things I can do now:
>
> 1. Make myself a hat from the left over tin foil and hope I get a
> moment of clarity.
> 2. Accept the status quo, it is working after all, I just don't
> understand why.
> 3. Futz with the antena setup further, mast head amp, new UHF aerial
> closer to the PC, professional installer.
> 4. Buy a PCI/PCIe based tuner and hope it works better.
>
> Any ideas/comments/etc greatly appreciated.
>
>
> Thanks,
>
> Dylan
>
>
> [1] In case people don't know, most cables (RF, cat5/6) had printing
> on the casing every meter. Somewhere buried in the writing is the
> number of meters left on the reel. If you can find the writing closest
> to each end of a cable you can subtract the two values and determine
> how long your cable is :)
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> mythtvnz mailing list
> mythtvnz[at]lists.linuxnut.co.nz
> http://lists.ourshack.com/mailman/listinfo/mythtvnz
> Archives http://www.gossamer-threads.com/lists/mythtv/mythtvnz/
>

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dylan at deedums

Nov 5, 2009, 1:43 AM

Post #5 of 10 (484 views)
Permalink

Re: Tinfoil madness [In reply to]

Before I get into the detailed response, it's been pointed out that
it's rather poor form to attach images to messages like this, rather I
should have included a URL to the image. Sorry for my spammer like
behaviour :(

On Thu, Nov 5, 2009 at 8:11 PM, stuart <stugo[at]xtra.co.nz> wrote:
>
> Hi Dylan
> �I will throw in my two cents worth in. First I do not have any Sat gear
> set up, must get round to it.
> But I am a sparky so I will throw in some ideas.
> �As has been pointed out a multi meter with some testing info would
> help, a ups even a interactive and not a double conversion type will
> probably not sort out a grounding or earthing fault.
> �The think that leaps out is that the is no problem when isolated from
> the mains, on battery. But I do have a question, does your signal
> improve or do they remain the same?

The signal remains the same, just the BER and bad blocks varies.

The UPS in question is a fairly flash (but elderly) unit that does the
whole regenerate the power thing, and just to be sure I ran the tests
twice, once with the UPS connected to the mains, and once running on
battery. This didn't seem to make any difference.

I brought one of these (http://jaycar.co.nz/productView.asp?ID=QP2000)
yesterday and tested a bunch of power points around the house
including the power strips with the server/UPS connected. Everything
appears fine :) I also verified that all my RCD's work :)

I removed the cover from the fuse box (at the suggestion of another
electrical in the know person) and eyeballed all the ground and
neutral connections to look for obviously loose connections or
blackening/scorching. I didn't go as far as sticking a screw driver in
and tightening everything. I feel thats a job for someone qualified :)
I didn't find anything to concern me.

Dean suggested: "What happens if you remove the foil, but earth the
antenna, cable shield and the splitter?" - Anytime I remove the foil
from the USB sticks the BER rises and it becomes erratic. I tried
earthing the splitter housing but this didn't make any difference.

> I can give you instructions on how to test you earthing at power point
> and gear to a ruff level with out spending heaps of money on special gear
> but you will need at least a cheap meter.

I have a basic digital multimeter and a rather elderly oscilloscope so
any instructions that don't involve my wife claiming on my life
insurance would be appreciated :)

> If it remains the same I would try a get that up, I may be wrong but I
> thought that getting it around 70% or above would me preferable.

I think you've hit the nail on the head. I have a new bit of data from
last night. The signal levels on all three transponders dropped around
1-2% last night due I think to some very misty weather. During this
time all three transponders experienced higher BER and bad blocks to
the point they were unwatchable.

This evening the mist is gone and the levels are back where I expect them.

This suggests to me the signal is just too weak if such a small drop
is enough to tip it over the edge.

> One last thing �as I do not now the area you are in, but is the actual
> aerial actually the correct one for the area, A electrical supplier like
> Rexel, usually will be able to check, I noticed that one I had was
> different from the neighbors and was the wrong type.

I'm in the Johnsonville (Wgtn) area, at the foot of Kaukau. I'm very
close to the transmitter, but thanks to a lump in the hill don't have
line of sight :(

It's roughly the same size/shape/style as the neighbours but I get the
strongest signal pointing it a slightly different direction than
everyone else (maybe 15 degrees).

My plan at this stage is to borrow a Fluke cable tester we have at
work (it does cat5/6 and I think coax) and just verify I haven't
munted one of the cables, for example failed to connect the shield
correctly.

I'm also going to pick up a masthead amp. I'm looking at either
http://www.freeviewshop.co.nz/kingray-24db-shielded-digital-mast-head-amplifier-p-482.html
or http://jaycar.co.nz/productView.asp?ID=LT3270 . Hopefully this
isn't throwing good money after bad :)

The Jaycar unit is a little cheaper, but for some reason the pictures
of the Kingray unit convey a sense of quality.

Thanks for everyones comments so far :) I'll do some more tinkering
and report back next week.

Dylan

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tortise at paradise

Nov 5, 2009, 2:17 AM

Post #6 of 10 (484 views)
Permalink

Re: Tinfoil madness [In reply to]

----- Original Message -----
From: "Dylan Hall" <dylan[at]deedums.com>
To: "MythTV in NZ" <mythtvnz[at]lists.linuxnut.co.nz>
Sent: Thursday, November 05, 2009 10:43 PM
Subject: Re: [mythtvnz] Tinfoil madness

This evening the mist is gone and the levels are back where I expect them.

Hmmm Sounds like a better aerial position is worth seeking, not sure if it can be achieved from what you've said though.

In summary it seems the USB tuners work fine on the notebook but not the PC.

Could the PC Power Supply unit be producing interference that you are effectively shielding? Or the adjacent speakers magnetism?
Or the printer?

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robert at fisher

Nov 5, 2009, 9:33 AM

Post #7 of 10 (470 views)
Permalink

Re: Tinfoil madness [In reply to]

On Thu, 05 Nov 2009 23:17:46 Tortise wrote:

> In summary it seems the USB tuners work fine on the notebook but not the
> PC.
>
You haven't got USB extender cables on the PC have you?
I have experienced loss through those with some devices i.e. the device works
fine when plugged directly into the mobo but not when using the extension
cable.

Rob

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Douglas.Pearless at pearless

Nov 5, 2009, 3:01 PM

Post #8 of 10 (465 views)
Permalink

Re: Tinfoil madness [In reply to]

How many other USB devices do you have plugged in, perhaps you are close to the limit of the USB hub (some 500mA I seem to recall, but I may be wrong)

Quoting Robert Fisher <robert[at]fisher.net.nz>:

> On Thu, 05 Nov 2009 23:17:46 Tortise wrote:
>
>> In summary it seems the USB tuners work fine on the notebook but not the
>> PC.
>>
> You haven't got USB extender cables on the PC have you?
> I have experienced loss through those with some devices i.e. the device works
> fine when plugged directly into the mobo but not when using the extension
> cable.
>
> Rob
>
> _______________________________________________
> mythtvnz mailing list
> mythtvnz[at]lists.linuxnut.co.nz
> http://lists.ourshack.com/mailman/listinfo/mythtvnz
> Archives http://www.gossamer-threads.com/lists/mythtv/mythtvnz/
>

blmiller at slingshot

Nov 5, 2009, 11:27 PM

Post #9 of 10 (455 views)
Permalink

Re: Tinfoil madness [In reply to]

Dylan Hall wrote:
> Before I get into the detailed response, it's been pointed out that
> it's rather poor form to attach images to messages like this, rather I
> should have included a URL to the image. Sorry for my spammer like
> behaviour :(
>
> On Thu, Nov 5, 2009 at 8:11 PM, stuart <stugo[at]xtra.co.nz> wrote:
>>
>> Hi Dylan
>> I will throw in my two cents worth in. First I do not have any Sat
>> gear set up, must get round to it.
>> But I am a sparky so I will throw in some ideas.
>> As has been pointed out a multi meter with some testing info would
>> help, a ups even a interactive and not a double conversion type will
>> probably not sort out a grounding or earthing fault.
>> The think that leaps out is that the is no problem when isolated from
>> the mains, on battery. But I do have a question, does your signal
>> improve or do they remain the same?
>
> The signal remains the same, just the BER and bad blocks varies.
>
> The UPS in question is a fairly flash (but elderly) unit that does the
> whole regenerate the power thing, and just to be sure I ran the tests
> twice, once with the UPS connected to the mains, and once running on
> battery. This didn't seem to make any difference.
>
> I brought one of these (http://jaycar.co.nz/productView.asp?ID=QP2000)
> yesterday and tested a bunch of power points around the house
> including the power strips with the server/UPS connected. Everything
> appears fine :) I also verified that all my RCD's work :)
>
> I removed the cover from the fuse box (at the suggestion of another
> electrical in the know person) and eyeballed all the ground and
> neutral connections to look for obviously loose connections or
> blackening/scorching. I didn't go as far as sticking a screw driver in
> and tightening everything. I feel thats a job for someone qualified :)
> I didn't find anything to concern me.
>
> Dean suggested: "What happens if you remove the foil, but earth the
> antenna, cable shield and the splitter?" - Anytime I remove the foil
> from the USB sticks the BER rises and it becomes erratic. I tried
> earthing the splitter housing but this didn't make any difference.
>
>> I can give you instructions on how to test you earthing at power
>> point and gear to a ruff level with out spending heaps of money on
>> special gear but you will need at least a cheap meter.
>
> I have a basic digital multimeter and a rather elderly oscilloscope so
> any instructions that don't involve my wife claiming on my life
> insurance would be appreciated :)
>
>> If it remains the same I would try a get that up, I may be wrong but
>> I thought that getting it around 70% or above would me preferable.
>
> I think you've hit the nail on the head. I have a new bit of data from
> last night. The signal levels on all three transponders dropped around
> 1-2% last night due I think to some very misty weather. During this
> time all three transponders experienced higher BER and bad blocks to
> the point they were unwatchable.
>
> This evening the mist is gone and the levels are back where I expect
> them.
>
> This suggests to me the signal is just too weak if such a small drop
> is enough to tip it over the edge.
>
>> One last thing as I do not now the area you are in, but is the actual
>> aerial actually the correct one for the area, A electrical supplier
>> like Rexel, usually will be able to check, I noticed that one I had
>> was different from the neighbors and was the wrong type.
>
> I'm in the Johnsonville (Wgtn) area, at the foot of Kaukau. I'm very
> close to the transmitter, but thanks to a lump in the hill don't have
> line of sight :(
>
> It's roughly the same size/shape/style as the neighbours but I get the
> strongest signal pointing it a slightly different direction than
> everyone else (maybe 15 degrees).
>
> My plan at this stage is to borrow a Fluke cable tester we have at
> work (it does cat5/6 and I think coax) and just verify I haven't
> munted one of the cables, for example failed to connect the shield
> correctly.
>
> I'm also going to pick up a masthead amp. I'm looking at either
> http://www.freeviewshop.co.nz/kingray-24db-shielded-digital-mast-head-amplifier-p-482.html
> or http://jaycar.co.nz/productView.asp?ID=LT3270 . Hopefully this
> isn't throwing good money after bad :)
>
> The Jaycar unit is a little cheaper, but for some reason the pictures
> of the Kingray unit convey a sense of quality.
>
> Thanks for everyones comments so far :) I'll do some more tinkering
> and report back next week.
>
> Dylan
>
>
Dylan,
Top marks for experimentation.
GME Kingray product is much better than Jaycar.
Jaycars prices are not always so sharp.
Can not beat signal strength from the source or antenna, does your antenna
have enough gain ?

Your hill will complicate the alignment as UHF is line of sight.
All coaxial cable has loss no matter how good it is & as you said "failed to
connect the shield correctly" could be your problem.

Problem with normal television RF cabling methods is that there is no
galvanic isolation thru' normal splitters & sometime you need to use DC for
power & control.
Maybe you can buy a fully isolating splitter, would be easy to make if you
can get the appropriate connectors.
I have never seen this part but I have not had to look.

Masthead amps are good to compensate for cable length & splitter loss.
Digital TV was meant to be more immune to noise/interference but this was
just an excuse to make the tuner more cheaply.

Cheap & old PC SMPS are prime candidates for noise generators as are
electronic ballast fluorescent lights (energy savers).

Does your laptop with USB tuner work sitting next to basement PC ?
With PC connected & not ?

Remember that your scope is a single ended input device, the impedance to
GND thru' probe ground clip is low.
The scope GND is connected to power lead earth.

Different earth currents in diff parts of the house is unavoidable due to
our MEN power system & increasing amount of SMPS equipment.

Brett.

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stugo at xtra

Nov 6, 2009, 8:01 PM

Post #10 of 10 (424 views)
Permalink

Re: Tinfoil madness [In reply to]

If you measure between the earth and the neutral at the power point on
the ohms scale it should be as close to 0 ohms.
This would prove that you have a good connection at the sub board and
main board with out springing for anything flashier.
I noticed that you mentioned RCD are the at your board, just curious as
this gives me a idea of the age of you house wiring.
Stu

Brett Miller wrote:
> Dylan Hall wrote:
>
>> Before I get into the detailed response, it's been pointed out that
>> it's rather poor form to attach images to messages like this, rather I
>> should have included a URL to the image. Sorry for my spammer like
>> behaviour :(
>>
>> On Thu, Nov 5, 2009 at 8:11 PM, stuart <stugo[at]xtra.co.nz> wrote:
>>
>>> Hi Dylan
>>> I will throw in my two cents worth in. First I do not have any Sat
>>> gear set up, must get round to it.
>>> But I am a sparky so I will throw in some ideas.
>>> As has been pointed out a multi meter with some testing info would
>>> help, a ups even a interactive and not a double conversion type will
>>> probably not sort out a grounding or earthing fault.
>>> The think that leaps out is that the is no problem when isolated from
>>> the mains, on battery. But I do have a question, does your signal
>>> improve or do they remain the same?
>>>
>> The signal remains the same, just the BER and bad blocks varies.
>>
>> The UPS in question is a fairly flash (but elderly) unit that does the
>> whole regenerate the power thing, and just to be sure I ran the tests
>> twice, once with the UPS connected to the mains, and once running on
>> battery. This didn't seem to make any difference.
>>
>> I brought one of these (http://jaycar.co.nz/productView.asp?ID=QP2000)
>> yesterday and tested a bunch of power points around the house
>> including the power strips with the server/UPS connected. Everything
>> appears fine :) I also verified that all my RCD's work :)
>>
>> I removed the cover from the fuse box (at the suggestion of another
>> electrical in the know person) and eyeballed all the ground and
>> neutral connections to look for obviously loose connections or
>> blackening/scorching. I didn't go as far as sticking a screw driver in
>> and tightening everything. I feel thats a job for someone qualified :)
>> I didn't find anything to concern me.
>>
>> Dean suggested: "What happens if you remove the foil, but earth the
>> antenna, cable shield and the splitter?" - Anytime I remove the foil
>> from the USB sticks the BER rises and it becomes erratic. I tried
>> earthing the splitter housing but this didn't make any difference.
>>
>>
>>> I can give you instructions on how to test you earthing at power
>>> point and gear to a ruff level with out spending heaps of money on
>>> special gear but you will need at least a cheap meter.
>>>
>> I have a basic digital multimeter and a rather elderly oscilloscope so
>> any instructions that don't involve my wife claiming on my life
>> insurance would be appreciated :)
>>
>>
>>> If it remains the same I would try a get that up, I may be wrong but
>>> I thought that getting it around 70% or above would me preferable.
>>>
>> I think you've hit the nail on the head. I have a new bit of data from
>> last night. The signal levels on all three transponders dropped around
>> 1-2% last night due I think to some very misty weather. During this
>> time all three transponders experienced higher BER and bad blocks to
>> the point they were unwatchable.
>>
>> This evening the mist is gone and the levels are back where I expect
>> them.
>>
>> This suggests to me the signal is just too weak if such a small drop
>> is enough to tip it over the edge.
>>
>>
>>> One last thing as I do not now the area you are in, but is the actual
>>> aerial actually the correct one for the area, A electrical supplier
>>> like Rexel, usually will be able to check, I noticed that one I had
>>> was different from the neighbors and was the wrong type.
>>>
>> I'm in the Johnsonville (Wgtn) area, at the foot of Kaukau. I'm very
>> close to the transmitter, but thanks to a lump in the hill don't have
>> line of sight :(
>>
>> It's roughly the same size/shape/style as the neighbours but I get the
>> strongest signal pointing it a slightly different direction than
>> everyone else (maybe 15 degrees).
>>
>> My plan at this stage is to borrow a Fluke cable tester we have at
>> work (it does cat5/6 and I think coax) and just verify I haven't
>> munted one of the cables, for example failed to connect the shield
>> correctly.
>>
>> I'm also going to pick up a masthead amp. I'm looking at either
>> http://www.freeviewshop.co.nz/kingray-24db-shielded-digital-mast-head-amplifier-p-482.html
>> or http://jaycar.co.nz/productView.asp?ID=LT3270 . Hopefully this
>> isn't throwing good money after bad :)
>>
>> The Jaycar unit is a little cheaper, but for some reason the pictures
>> of the Kingray unit convey a sense of quality.
>>
>> Thanks for everyones comments so far :) I'll do some more tinkering
>> and report back next week.
>>
>> Dylan
>>
>>
>>
> Dylan,
> Top marks for experimentation.
> GME Kingray product is much better than Jaycar.
> Jaycars prices are not always so sharp.
> Can not beat signal strength from the source or antenna, does your antenna
> have enough gain ?
>
> Your hill will complicate the alignment as UHF is line of sight.
> All coaxial cable has loss no matter how good it is & as you said "failed to
> connect the shield correctly" could be your problem.
>
> Problem with normal television RF cabling methods is that there is no
> galvanic isolation thru' normal splitters & sometime you need to use DC for
> power & control.
> Maybe you can buy a fully isolating splitter, would be easy to make if you
> can get the appropriate connectors.
> I have never seen this part but I have not had to look.
>
> Masthead amps are good to compensate for cable length & splitter loss.
> Digital TV was meant to be more immune to noise/interference but this was
> just an excuse to make the tuner more cheaply.
>
> Cheap & old PC SMPS are prime candidates for noise generators as are
> electronic ballast fluorescent lights (energy savers).
>
> Does your laptop with USB tuner work sitting next to basement PC ?
> With PC connected & not ?
>
> Remember that your scope is a single ended input device, the impedance to
> GND thru' probe ground clip is low.
> The scope GND is connected to power lead earth.
>
> Different earth currents in diff parts of the house is unavoidable due to
> our MEN power system & increasing amount of SMPS equipment.
>
> Brett.
>
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