66 replies to this topic

[alanh]

Blue = New Zealand
Firstly, get the maximum signal from the antenna itself by selecting the correct type for your area with the maximum number of dB. Note: Signal levels on channels 6-12 where used can be higher than the channels ≥27.

Cable losses increase as the cable gets longer and the channel number increases.

Amplifiers on this list can amplify the signal up to 25 000 times so overloading can occur if the antenna signal is too strong. This is where an antenna installer should measure the signal levels to ensure you can get the correct signal strength into the amplifier and into the receivers.

Excessive gain can remove the signals from the amplifier output or this can happen with impulse interference only. If this happens it is impossible to remove the interference from the signal. So to remove unwanted interference filtering is advised.

Filtering
Australia uses;
Band 3  174 - 230 MHz (RF channels 6 - 12)
Band 4  519 - 589 MHz (RF channels 27 - 36)
Band 5  582 - 820 MHz (RF channels 36 - 69)
After 2013 band 5 will be reduced to 582 - 694 MHz (RF channels 36 - 51). Two band 3 channels will be changed to DAB+ digital radio.

Europe uses;
Band 3 174 - 230 MHz (RF channels 5 - 12)
Band 4 470 - 598 MHz (RF channel 21 - 35) = Au RF ch 20 - 36
Band 5 598 - 862 MHz (RF channel 36 - 64) = Au RF ch 37 - 75
Digital Dividend will sell 590 - 862 MHz (RF channel 56 - 64)

To remove all non Digital TV signals Kingray fl3bmh. Use the configuration on page 4 bottom left, position A
Since no Band 3 is used for NZ DTV, then a standard VU diplexer only using the U input will do the same job (except for UHF two way communications & pagers.)

It removes interference from impulse noise, AM, FM and CB radio (27 MHz and UHF), pagers and mobile phone repeater signals.

Where UHF antennas are designed to receive channels 21-27, this filter will remove UHF CB and mobile communications interference.

Band 3
It must only be used in with a phased array in horizontal polarisation or the highest gain Yagi in Vertical polarisation. The signals must be very weak. The band 3 antenna needs to be fed into a   Kingray fl3bmh followed by MHW42FS's V input (38 dB gain). Alternatively MHV44HLG contains a band 3 only input, it is not shielded and does not use F connectors.
Johansson 10MM-J35BF
Hills A3PU and include band 3 filter 30 dB gain.

Band 5
MHU44B5G Internal filter passes channel 38-69, 38-62
MHU34FS Removes channels 20-27, 21-27
Johansson10MM-J40EF Amplifier 40dB Channels 45-69 (Matchmaster) 42 - 62

Bands 4 - 5
MHU24FS, MHU34FS or MHU42FS
Hills A2A  32 dB gain. Do not use the V input.
For the weakest signals only Kingray MHU44g

Band 3, 4-5
Not for NZ DTV
Hills C1501LND
Use the  Kingray fl3bmh  or Johansson 09MM-HL12Fto remove any signals below channel 6. Note: the Johansson 09MM-HL12F does not remove the 470 - 519 MHz which is used for 2 way radio & UHF CB which the  Kingray fl3bmh does.
MHW24FS
MHW34FS
MHW42FS
Hills A2A  32 dB gain.
Johansson 10MM-J35BF Amplifier B3/UHF Channel range ? (Matchmaster)
Digimatch 10MM-MA24UP UHF channel range ? (Matchmaster)

Kingray also make Masthead distribution amplifiers MDA20H Frequency range 174 - 860 MHz. If there is strong 2 way radio or mobile phone interference a Kingray fl3bmh will be required between the antenna and MDA20H.

DJ Coulter, Matchmaster and Laceys sell the Kingray range and Jaycar, Dick Smith sells some models.

AlanH
Please post errors and omissions here

Edited by alanh, 13 November 2010 - 12:31 AM.

[beeblebrox]

Alan,

Also the Kingray MDA20H and MDA20U are very effective too and only amplify Band345 or B and 45 respectively, also don't have too much gain which can often be a problem with the MWx34FS if not correctly sized/installed.....

[gclark8]

Alan,

Televes have a UHF mast head amp in the DAT UHF DIGITAL RANGE with an active impulse noise filter: http://www.televes.c...ndice.asp?SEC=1.

[dig2all]

laceys.tv say they sell a lot of their alcad mast amplifiers, and i've heard of installers who will use nothing else.

[alanh]

beeblebrox,
I cannot find those models in their website
George,
I looked in the Televes catalog, it is a Yagi antenna with 3 booms for UHF and a small Band 3 antenna with reflector on the back. You can substitute the balun for a 13 dB UHF amplifier. VHF bypasses this amplifier. Their claim is that the amplifier output matches the cable impedance. However you can do the same thing with a masthead amplifier of your choice mounted on the pole a metre below. Any mismatch reflections will be so close to the original signal you will not be able to see them. I can guarantee that 3 Yagis in parallel will not give you 75 ohms without a turns ratio in a transformer.

dig2all,
I looked through Laceys catalog, there is no interference filtering in the Alcad masthead amplifiers. Laceys also stock the Kingray products including the filter I mentioned. So if you wish to add a Kingray fl3bmh ahead of the Alcad amplifiers go for it.

Televese also have an indoor UHF amplifier which has a high gain and a sharp filter cut off at 860 MHz to stop mobile phone interference!

AlanH

[dig2all]

that's not right alanh, of course they have interference filtering.

[beeblebrox]

Alan,

That's because they haven't updated the website in two years!!!  

The MDA20H and MDA20U are ideal for digital amplification as they do not amplify band one unlike most other wideband amps out there therefore you don't need the use a FL3BPMH.

Specs from the Kingray 2006 catalog...

MDA20H 174-470Mhz VHF 470-860 Mhz UHF, Gain 19dB Noise < 1.6dB Filters <174Mhz Fully Shielded (why would you use anything else)

MDA20U 470-860Mhz UHF Gain 19dB Noise < 1.6db Filters 520Mhz Hp Fully Shielded

The MDA20H is ideal for a band 3/4/5 situation.. 19 dB is typically enough gain for most digital situations and it has a particularly good noise factor compared to most other amps on the market.

Given everything is going Digital why are the other Amplifier manufacturers continuing with Wideband Amps that include Band 1 in our market...

[alanh]

beeblebrox,
I wholeheartedly agree with your last statement. It is not only amplifier manufacturers but also antenna makers as well. Imports will always start band 4 at 470 MHz which is channel 21 and not channel 28 576 MHz.

The advantage of fl3bmh is that it also has a notch at 477 MHz which is channel 21 which is very deep to keep out UHF CB and also a deep filter to keep out Mobile phones.

dig2all, Give me some models and their specifications. Laceys also sell the Kingray range. I am not connected with any of these companies. I just want pixellated free reception for all. After all when you pick up a colour printed magazine there is no pixellation unless some one is to be hidden so why isn't DTV!

AlanH

[dJOS]

beeblebrox, on May 15 2006, 12:00 PM, said:

Alan,

Also the Kingray MDA20H and MDA20U are very effective too and only amplify Band345 or B and 45 respectively, also don't have too much gain which can often be a problem with the MWx34FS if not correctly sized/installed.....

Nice avatar BB.  

[poidahl]

I respond to AlanH's request for details of mast amplifiers sold by Laceys.tv.  

AlanH is right, we are Kingray distributors and are happy to recommend their products.  You mention FL3BPMH, I would point out that is only a filter and should not be confused with a mast amplifier.  However the best solution is a single channel head end that uses one filter to pass each channel, like our Fracarro KF, that blocks all interfering signals entering a TV Distribution system as it only passes the TV frequencies required!

Pages 41 to 43 of Laceys.tv Cat104 describes more than 20 Alcad and Fracarro mast amplifier models with a range of input / filtering configurations, each of which has a niche.  You suggest you have seen this, is there something about our presentation you do not understand?  Your suggestions would be welcome.

What features do you seek,  perhaps I can suggest a model?  After all that is what we do for antenna guys daily.

[beeblebrox]

Peter,

Whilst Single channel amps are the way to go in most commercial situations, in a normal domestic situation (single dwelling or small unit complex) they are overkill.  

Are any of Lacey's suppliers (other than Kingray) going to provide an amplifier specifically for the digital market?  ie a 174-230Mhz  and 520-820Mhz specifically blocking Band 1/2 with a low noise figure?

If we are serious about using the best gear for a digital installation then we  need to have the right tools for the job, the right antenna, good quality RG6 cable, fconnected splitters and wall plates, and the right amplifier for the job if required.  And of course if you're a professional installer a T40/PDA7/Prodig5/etc.. meter...

[bellotv]

Using single channel amps in a domestic situation might be overkill but so is all this talk of using special bandpass filters etc.
Many places DON'T have pager transmitters .DON'T have CB interferrance  and DON'T have mobile phone towers nearby.There is no need to fit these expensive filters if there is no problems.
Fitting these relatively expensive filters to every installation is more of a sin than not.In my area I have come across three locations where interferance from the above interfereres have been a problem and the kingray FL3BPMH fixed prior to mast head.
I use Alcad and Fraccaro masthead amps and they are fine.If I have a RARE INTERFERRANCE PROBLEM then I fit  a bandpass filter.

We only have UHF digital here so Band 123 not an issue.

One thing that worries me about the above mentioned kingray  bandpass filter is the use of slide switches and their potential to cause problems due to contact oxidization/corrossion.I think Kingray would have been better using gold plated headers and links.Time will tell.

[beeblebrox]

Bellotv ,

I'm with you, I'd only be using the Bandpass filter if required.. the bulk of the installs we do, we use  the right antenna and where required the right amplifier and in doing that I think I've only had to install one of these filters in probably 1 out of the last 100 digital installs I've done.  Not only is the possibility of oxidization on the switches but they do have a couple of dB insertion loss which if not required is a waste.

Most of the interference problems we see are normally on VHF and the bulk of the UHF jobs I go to where people are having interference problems it's usually because some bozo has installed a wideband amp instead of a UHF amp...

[Jeffry]

I recently upgraded an installation and tried various amplifier configurations -it is an extreme fringe location.
Moving the aerial sysytem to the other end of the house, replacing the existing Wisi UHF phased array with a Hills SF91B4+ and the ancient Hills Masthead amplifier with a Kingray MHW34GP improved analogue reception from virtually unwatchable to just very poor quality.

A Strong SRT5020 STB gave indifferent digital performance with frequent loss of lock an all channels (Central Tablelands 36, 37, 40, 42 & 43). I know from previous experience this is a very well performing STB in difficult locations.

Replacing the masthead amplifier with a Hills LNDA (low noise digital amplifier) showed reduced signal strength on all channels -as would be expected with 10dB less nominal gain. But, it also showed appreciably lower signal 'quality' figures on the STB -not expected as the LNDA is promoted as a low noise amplifier with good out of band filtering for optimal digital performance. Needless to say digital performance was not inproved and analogue picture quality was slightly reduced.

Adding an unbranded in-line amplifier (Lacey catalogue number LA1-18F) before the filter, to restore signal level gave, not only much better signal levels but also substantially improved 'quality' readings and excellent digital performance plus acceptable analogue performance at other than the main outlet.

Despite what I thought this seems to indicate some correlation between signal strength and quality for digital and a check on spectrum analyser certainly showed the last configuration gave much better looking digital signals. At that stage I packed up as the customer was satisfied with the result.

Does anyone have any thoughts on the situation? Maybe I overlooked something else that is also significant.

Jeff

[alanh]

Jeffry,
If the receiver is near the digital cliff, the quality figures will also be poor because the demodulator must remain locked solidly to the signal frequency. If not the errors generated will give poor quality figures. Remember that the frequency control is due to a phase locked loop which is a feedback system. There is a time constant to prevent it chasing its tail, however it makes it slower to respond to noise.

AlanH

[M'bozo]

Quote

Despite what I thought this seems to indicate some correlation between signal strength and quality for digital and a check on spectrum analyser certainly showed the last configuration gave much better looking digital signals.

Well, yes there is. Not everyone can see that though. And if you are using the set top box strength & quality indicators, you could be on a slippery slope.

Quote

Does anyone have any thoughts on the situation? Maybe I overlooked something else that is also significant.

I'm wondering what cBER & aBER readings were measured at the antenna & the outlet. I have read the text carefully, and it seems a LNDA & LA1-18F are in series, for an overall gain of 42dB and a noise figure of around 7dB.

For this situation I would have investigated a Fracarro 20/4046 (AU C34 - 49, 14dB gain) coupled to a MHU44G (44dB gain, nf around 2.5dB). In saying that, for long distance diffuse reception of digital signals, more often than not I end up using equivalents to the WISI phased array, and the aforementioned MHU44G with DC power supply.

Marc.

[bellotv]

Not to sure how you powered it,but I read it that you put the inline amp BETWEEN the antenna and the LNDA.

Antenna >>>>LA1-18f>>>>LNDA ?

From memory
This was suggested by James T Kirk ( broadcast engineer) last year but was shot down in flames as bad practice.
He suggested using a Kingray MDA20 wideband amp ( less than 1.6dB noise )>>>filters>>>then more amplification.

In a band filtered amp,the filter networks may attenuate the signal by 2dB or more before any amplification occurs.
If you have extremely weak signal to begin with then its an issue.
Placing the wideband amp first gives the best signal to noise gain before the filter .

Its concidered bad practice to wideband amplify before filtering but in the bush were the signals are extremely weak,you are usually far away from other sources of interferrance that would require filtering to avoid amplifier overload.(electric fences excluded)

Bellotv

[mtv]

Once again, we often have to throw away the theory books..... and do whatever works.

[TV4FREE]

beeblebrox, on May 17 2006, 09:49 AM, said:

........going to provide an amplifier specifically for the digital market?  ie a 174-230Mhz  and 520-820Mhz specifically blocking Band 1/2 with a low noise figure?

small example from the guys at FTE Maximal. They make Mast heads with inside filters, simple plug and play. You can even ask for specific channels numbers if required. example HERE

[mtv]

TV4FREE, on Jan 21 2008, 12:53 PM, said:

small example from the guys at FTE Maximal. They make Mast heads with inside filters, simple plug and play. You can even ask for specific channels numbers if required. example HERE

Good concept. (had a giggle at the English translation)

The noise figures are a bit high.

Who's the Australian distributor?

[beeblebrox]

cBER and PvBER would be useful when looking at these type of problems... even the C/N would probably be telling too..

Have hills modified the LNDA to take out B1 yet.. they said they were going to 2-3 years ago..   I'm with M'bozo a good UHF antenna and an appropriate UHF amp like the MHU34FS or MHU44G (not fconnected unfortunately) or the Ikusi SBA100 that has 40dB gain and a noise figure of <2.  Just so often are wideband amps bringing in and amping unwanted noise.

[Jeffry]

Thanks for the responses.

The LNDA was at masthead and the in-line amplifier at input to splitter (after LNDA).
Noise figure in this configuration is barely worse than LNDA alone -first (input) amplifier stage mostly determines noise figure.
I often use Fracarro 20/40-46 for digital only but in this installation there are 3 other outlets, analogue only and performance on SBS 29 with these can be marginal.
I didn't have a MHU44 on the truck; otherwise I probably would have tried that (likewise I didn't have one of the equivalent Alcads with me -I have found them very good).
And, I was certainly skating right at the cliff edge.
Perhaps the moral of this is best summarised by "Once again, we often have to throw away the theory books..... and do whatever works." Be prepared to try different alternatives and see what happens.
I used the STB to get relative readings quickly. I know they are not calibrated instruments but I was looking, at that stage for improvement or not.

BER and C/N were pretty terrible in any configuration I actually checked but I did not record figures. The principal aim was to get a result and spend minimum time (money) doing so.

I would be happy to see more anecdotal stories like this just to get a feel for the types of things that might work in very marginal situations.

cheers
Jeff

[Jeffry]

beeblebrox, on Jan 21 2008, 05:11 PM, said:

cBER and PvBER would be useful when looking at these type of problems... even the C/N would probably be telling too..

Have hills modified the LNDA to take out B1 yet.. they said they were going to 2-3 years ago..   I'm with M'bozo a good UHF antenna and an appropriate UHF amp like the MHU34FS or MHU44G (not fconnected unfortunately) or the Ikusi SBA100 that has 40dB gain and a noise figure of <2.  Just so often are wideband amps bringing in and amping unwanted noise.

I don't know but my thoughts, for what they are worth;
When (if) analogue transmissions are turned off (2012, I doubt it) all Terrestial TV should be transferred to UHF and freed up spectrum is available for tender -bet the politicians understand that last bit!

In fact, maybe all TV in this country should be delivered by satellite. License areas is not an issue -sell smartcards at newsagents or post offices and have postcode as determinant of which version of various network signals can be decoded. Otherwise everyone will be getting all their TV via internet anyway and how do you restrict that geographically? Why should it be restriced geographically anyway?

Few cans of worms there but maybe technical people can unravel some of them. The Politicians, bureaucrats and big business have already managed to stuff it up pretty well. Technocrats couldn't do worse surely?

cheers
Jeff

Edited by Jeffry, 21 January 2008 - 06:33 PM.

[mtv]

I agree that UHF would have been the way to go, but it was decided that in metro areas, the existing VHF infrastructure would keep installation costs down, but more importantly, that the majority of homes would not have to change their existing antennas. (according to the previous government)

Well, they certainly got that part wrong, as it appears to be the exact opposite, being that a very large percentage of people are required to perform some level of upgrade to their antennas/cabling etc.

Surely it must have been obvious that adding VHF channels 11 & 12 and expecting existing antennas only designed to work up to channel 10 to cope with the extended band would encounter problems.

[alanh]

Jeffry,
The power consumed by the transmitter increases as the channel number increases particularly at high powers. The coverage range is also less for the same radiated power. The losses in cabling is greater. So band 3 is the best compromise for large areas of Australia except where a local repeater is required. Then using the upper end of the UHF band is ok because the total power is small.

We are vacating 45-52, 54-70, 83-108 and 137 - 144 MHz (channels 0-5 & 5A) when analog is switched off.

AlanH