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Antenna Design Basics + Amplification


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#226 MIA DIGITAL

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Posted 21 July 2011 - 03:01 PM

Here in lies another problem with alanh, he never catches on that people with greater knowledge and experience are not seeking his input.

In this uncontrollable zeal to say more, as is typical, he searches for justification and just gets it so wrong again.

(eg) "The end result is that what ever the noise figure is, it will make the C/N ratio worse by this figure when it gets to the receiver." (This is simply wrong and the C/N degradation is level dependent)
(eg) "This also applies to the MER." (This is also wrong for the same reasons)

Alanh, just stop all this and we can stop showing you up because we won't need to protect the reader.

James

I love how you all wish Alanh would just
go away we all know what he is all about.
But you all still find the time to argue with him.I an installer myself with a lot still to learn.
And I know its you guys advice I would rather take for shore. Come on guys you are better than this .

Edited by MIA DIGITAL, 21 July 2011 - 08:34 PM.


#227 mtv

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Posted 21 July 2011 - 04:31 PM

I love how you all wish Alanh would just
go away we all know what he is all about.
But you all still find the time to argue with him.I an installer myself with a lot still to learn.
And I know its you guys advice I would rather take for shore. Come on guys you are better than this .

I agree, but when you now have alanh editing his posts without the 'edited' line being displayed, to change his posts to read differently to what he originally posted, often changing the context completely, readers need to be made aware of the misinformation he regularly sprouts. In particular where he advises readers MUST purchase a particular antenna, amp, etc, when what he states may in fact not be required at all.

As you will see in my last few posts about the MDA amps, I simply agreed with another installer about their performance, then alanh decided to address me with a detailded description about them, whilst later stating he assumed I would already know all about them.

There was no need for his posts at all (which goes for the majority of them... and you appear to agree). :)

#228 MIA DIGITAL

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Posted 21 July 2011 - 05:21 PM

I agree, but when you now have alanh editing his posts without the 'edited' line being displayed, to change his posts to read differently to what he originally posted, often changing the context completely, readers need to be made aware of the misinformation he regularly sprouts. In particular where he advises readers MUST purchase a particular antenna, amp, etc, when what he states may in fact not be required at all.

As you will see in my last few posts about the MDA amps, I simply agreed with another installer about their performance, then alanh decided to address me with a detailded description about them, whilst later stating he assumed I would already know all about them.

There was no need for his posts at all (which goes for the majority of them... and you appear to agree). :)

I do agree it's just that its hard to read the posts of installers I have heaps of respect for that I don't even know but have lerent so much from their advice and have put into practice and know to be true and sound advice get lost in all this BS .

#229 mtv

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Posted 21 July 2011 - 06:18 PM

I do agree it's just that its hard to read the posts of installers I have heaps of respect for that I don't even know but have lerent so much from their advice and have put into practice and know to be true and sound advice get lost in all this BS .


Sadly, that's what happens, the good (and accurate) information gets buried in the alanh BS.

#230 andrewlace

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Posted 08 August 2011 - 04:40 PM

All that I'm hearing from you is white noise ... can you guess the band?

MTV,
I assumed you know about the versions of MDA, I was really on about the noise figure. The end result is that what ever the noise figure is it will make the C/N ratio worse by this figure when it gets to the receiver. If the C/N at the wall plate is within a few dB of the AS1367 specification it can get you over the line.

AlanH



#231 fstic

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Posted 26 August 2012 - 05:34 PM

Does anyone have the ATV24DIG Antenna from Academy TV?
I am unsure which side (top or bottom (balun side)) of the boom the two loose elements fit on?

#232 nbound

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Posted 26 August 2012 - 06:45 PM

All that I'm hearing from you is white noise ... can you guess the band?

The Living End ;)

#233 nbound

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Posted 26 August 2012 - 06:46 PM

Does anyone have the ATV24DIG Antenna from Academy TV?
I am unsure which side (top or bottom (balun side)) of the boom the two loose elements fit on?


Theres a pic here: http://www.digitek.t...9b9402f52ab.jpg

#234 fstic

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Posted 26 August 2012 - 07:45 PM

Theres a pic here: http://www.digitek.t...9b9402f52ab.jpg

This pic is not clear to me. I can't see the balun. Looks like the two elements (3rd and 4th from the widest end) are in the centre of the looped element (2nd). This pic looks like the antenna is upside down because my balun is on the same side as the looped element.

#235 M'bozo

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Posted 26 August 2012 - 08:48 PM

Does anyone have the ATV24DIG Antenna from Academy TV?


Nope. Don't use them.


I am unsure which side (top or bottom (balun side)) of the boom the two loose elements fit on?


According to the website, it's a copy of the Hills SMX24, so I would presume the element goes on top of the boom, if one assumes the balun is down.


EDIT: To make sure I'm on the right page, does this help?

Edited by M'bozo, 27 August 2012 - 08:15 AM.


#236 fstic

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Posted 27 August 2012 - 02:25 PM

EDIT: To make sure I'm on the right page, does this help?


Yep. That helped heaps, thanks.

#237 vur

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Posted 08 September 2012 - 12:00 PM

I have two TV antennas. One causes a loud buzz from our home theatre receiver and receives all channels.The buzz is loud and gets louder with advancing the volume control. The other antenna is quiet but is very iffy with SBS (no signal or blocky or ok).
There is no buzz from the built in TV speakers with either antenna.
The system is a LED TV with audio out by analogue RCA cable to home theatre receiver (which has no digital inputs).
I believe the coax shielding is well connected at both ends for the buzzy antenna.
The buzz will sound too if the TV is only on standby and there is no antenna connected. It stops as soon as the "no buzz" antenna and TV antenna connector touch. Touching the buzzy antenna to the connector does not stop the buzz.
I have also tried a mate's antenna and it buzzed too.

#238 Digital Penetration

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Posted 08 September 2012 - 01:01 PM

I have two TV antennas. One causes a loud buzz from our home theatre receiver and receives all channels.The buzz is loud and gets louder with advancing the volume control. The other antenna is quiet but is very iffy with SBS (no signal or blocky or ok).
There is no buzz from the built in TV speakers with either antenna.
The system is a LED TV with audio out by analogue RCA cable to home theatre receiver (which has no digital inputs).
I believe the coax shielding is well connected at both ends for the buzzy antenna.
The buzz will sound too if the TV is only on standby and there is no antenna connected. It stops as soon as the "no buzz" antenna and TV antenna connector touch. Touching the buzzy antenna to the connector does not stop the buzz.
I have also tried a mate's antenna and it buzzed too.


Sounds like you've set up an earth loop. I make my own cables, so when this happens, I just disconnect the earth braid shield wire at one end of the cable in the plugs. If you (or a mate) can't do this, then try an audio isolation transformer in the analogue RCA cable - one end to isolation transformer inline and another cable from transformer to home theatre receiver. Jaycar has one http://www.jaycar.co...w.asp?ID=AA3086 with 3.5 stereo jack plugs and I'm sure they used to have one with RCA plugs, but I can't find it, so you'll have to ask.

Edited by Digital Penetration, 08 September 2012 - 01:03 PM.


#239 M'bozo

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Posted 08 September 2012 - 04:39 PM

The buzz will sound too if the TV is only on standby and there is no antenna connected.

That's a really important clue.

It stops as soon as the "no buzz" antenna and TV antenna connector touch.

So is that.

Touching the buzzy antenna to the connector does not stop the buzz.
I have also tried a mate's antenna and it buzzed too.

And these are good clues as well.

Are indoor antennas being talked about here?

So, if they are indoor antennas, what are the make & model numbers for the buzz / no buzz antennas?

And while we're at it, what make & model for the TV?*

*Probably a Samsung, but any LED TV with a 2 wire power cord will do.


Shh! Be vewy, vewy quiet. We're hunting Elmers. :rofl:

#240 alanh

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Posted 09 September 2012 - 07:55 PM

Vur,
Does the antenna which buzzes contain an amplfier which is usually powered by a plug pack to the power point?

Alanh

#241 vur

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Posted 13 September 2012 - 12:54 PM

Thanks for the thoughts, questions and suggestions everyone.

Digital penetration
I tried severing the cable braid close too (but not in) the plugs. Sorry it made no difference

M'bozo
Both antennas are outdoor. The buzz antenna is an Hills but the model sticker is illegible. It has a blue anodised "spine" and gold bars. The no buzz is Hills too with more bars and all silver but I can't see a model number.
The TV is a Kogan LED 3D KALED553D1ZP and is a 2 wire power cord

Magnum72
Tried buzzy antenna to receiver FM input. Still get buzz with TV on standby or on or fully off and receiver selecting TV or FM Tuner

alanH
no antenna amplifier


I wondered if the buzzy antenna was picking up a nastie but I have tried rotating it for any polarity effect and also pointing it in every direction and there is no change to the buzz

#242 M'bozo

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Posted 13 September 2012 - 06:34 PM

The TV is a Kogan LED 3D KALED553D1ZP and is a 2 wire power cord


When the home theatre is buzzing, does unplugging the TV from the power point make the buzz go away?

If yes, you need to ensure the TV is somehow connected to the building earth. This won't be happening, in & of itself, if the TV has a 2 wire power cord.

The easiest way I have found to overcome this, is to get a protected power board, with an antenna input/output connection, that has the antenna outer (shield) connection tied to building earth.

Then, when feeding the antenna lead through the board, it ties the TV chassis (in most cases) to earth, and the hum/buzz/interference goes.

#243 clipper

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Posted 14 September 2012 - 09:12 AM

that has the antenna outer (shield) connection tied to building earth.

A bit more detail please Marc.

#244 M'bozo

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Posted 14 September 2012 - 01:14 PM

A bit more detail please Marc.


OK.

Power board with FTA antenna in/out connection.

Multimeter on continuity setting.

On the power board, is there continuity (very low Ωs) between earth pin on power plug, and outer connection of the out FTA connection that goes to TV, etc?

Yes - done. (Assuming active/earth/neutral are connected correctly to the GPO, & the building doesn't have an O/C neutral*)

No - find another power board.


*I've come across faults like these. I'm not a sparky (should have been - had the option, passed on it.)

#245 vur

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Posted 14 September 2012 - 03:27 PM

Unplugging the TV does not make the buzz go away.

I have tried connecting a wire from earth to the antenna coax clamp (which clamps to the shielding). That had no effect on the buzz.

The soldering on the antennas' printed circuit board looks ok but I can't see the underside without busting attachments. Is there something there that may be the problem?

#246 M'bozo

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Posted 14 September 2012 - 04:45 PM

The buzz will sound too if the TV is only on standby and there is no antenna connected.


In this state, does unplugging the TV stop the buzz?

Is there something there that may be the problem?


In the balun? Unlikely. My next step would be to try an antenna isolator on the wallplate to see if this stops the buzz, when it is happening under these conditions.

#247 mtv

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Posted 15 September 2012 - 12:55 AM

This may be unrelated, but I've seen numerous audio noises generated by poorly-shielded flyleads and HDMI cables.

Worth checking.

#248 mtv

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Posted 15 September 2012 - 09:07 PM

Agreed MTV but why would the buzz stop when connecting to a different antenna?


Different coax used on the two antennas.

The 'buzzy' one has poorer shielding, some corrosion or moisture ingress perhaps.

Faulty connection on a wall outlet.

Difficult to determine without being there with a speccy to 'see' what's happening.

#249 M'bozo

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Posted 16 September 2012 - 07:27 AM

but why would the buzz stop when connecting to a different antenna?


I'm presuming an earth loop type issue here, since I'm not on the ground at the problem, and can't otherwise get a handle on it.

Antenna mast not earthed, earthed, parasitic earth through some other method, antenna has coaxial connection isolated from boom/not isolated from boom etc.

I sometimes use an analogue multimeter to assist when looking at these sorts of issues.

As Col mentions, the interconnecting leads could also be faulty.

#250 Storm AV

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Posted 17 September 2012 - 02:37 PM

Cheers fellas-makes sence,
just another one to throw in the mix-mice/rats-yum yum cables!