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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions.

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Old 6th Feb 2016, 8:52 am   #1
rbm1973
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Default Running more than one set from Aurora?

Any suggestions on running more than one set from an Aurora ?

I would like to run it through a distribution system. Has anyone any suggestions on this type and make of distribution amp needed
without any loss. I know that all sets would be on the same channel

I am also thinking of running the Aurora in a case with a small fan, as it does get a tiny bit warm after prolonged use. I know this is normal, but as i will be using it for quite long time periods I would like the back up of keeping it cool, for its own good.
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Old 6th Feb 2016, 11:02 am   #2
KeithsTV
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Default Re: Running more than one set from Aurora?

The Aurora output level is quite high, around 6mV according to the manual, so may overload an amplifier. If you are only feeding a couple of TVs then a simple splitter may suffice.

If you do use an amplifier make sure its frequency response goes down to 40MHz to cover Band 1 channels.

One thing to remember is that the Aurora output has a lot of harmonics present which could cause problems if fed through a distribution amplifier. Because of this there are several channel combinations that would not work if using two Auroras to simulate a two channel Band 1 & Band 3 system.

It may be worth feeding the output via a filter to attenuate the harmonics. You could try a triplexer combiner which has inputs for FM, DAB and UHF but only use the FM input for Band 1 signals or the DAB input for Band 3 signals and ignore the UHF input. This should attenuate the harmonics. You could then follow this with the distribution amplifier.

The distribution amplifier should ideally have an overall unity gain to avoid overloading the inputs of the TVs although extra gain may help some less sensitive TVs. It may be necessary to add attenuation at the input of the amplifier to achieve this.

The temperature of the Aurora depends on the input voltage as it uses a linear regulator. The closer to the minimum voltage (7V) the cooler it will run. I run mine from a 9V PSU.

Hope that helps

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Old 6th Feb 2016, 12:26 pm   #3
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Default Re: Running more than one set from Aurora?

At the last count , I have 30 Television receivers running from my "pair" of Auroras ? , it is fairly easy if you use some form of distribution amplifier , up to about 6 or so sets , a passive splitter will be fine as the aurora has plenty of output , if you really want to see how to do it , you should pay us a visit at the wireless museum at Dulwich where we now have upwards of 50 sets connected and working !
feel free to PM me for a chat
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Old 6th Feb 2016, 1:01 pm   #4
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Default Re: Running more than one set from Aurora?

Another point to bear in mind apart from harmonics is that as Aurora output is double sideband you cannot use adjacent channels (except for Ch 1 / 2 as AP was dsb)
I run my auroras from 7.5v and they run quite cool but I also have heatsinked output 'F' connectors - may be a bit of an overkill but I was able to 'fit and forget' system without any overheating concerns
Rgds - John
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Old 6th Feb 2016, 2:14 pm   #5
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Default Re: Running more than one set from Aurora?

Ask this lot http://www.aerialsandtv.com/ very helpful (no connexion etc.).
 
Old 6th Feb 2016, 4:55 pm   #6
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Default Re: Running more than one set from Aurora?

If you get a chance, have a word with a friendly Cable TV engineer, or a ceased CTV customer. They use resistive splitters and they're a throw-away component to them.
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Old 6th Feb 2016, 5:24 pm   #7
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Default Re: Running more than one set from Aurora?

I have a 9 way SLX distribution amplifier with two inputs, it is designed for one VHF/FM input and one UHF input. It works very well.

you should be able to just split the output of the Aurora between two/three sets no problem, as others have said, the output is very high.

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Old 6th Feb 2016, 10:08 pm   #8
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Default Re: Running more than one set from Aurora?

With that much output you could be a bit naughty and put aerials on the Aurora and the sets. A simple 1/4 wave bit of wire would work.
 
Old 11th Feb 2016, 9:23 pm   #9
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Default Re: Running more than one set from Aurora?

The biggest concern with connecting it to an aerial would be the harmonics which could interfere with broadcasts and other services on other frequencies. That is bound to cause problems somewhere (unless you live in the middle of nowhere), which you don't want.

Best to confine it to co-ax cable unless you can filter out all the harmonics and keep the power down to a level where it is undetectable outside your own home/workshop.
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Old 7th Mar 2016, 8:44 pm   #10
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Default Re: Running more than one set from Aurora?

Quote:
Originally Posted by petertheorgan View Post
... if you really want to see how to do it , you should pay us a visit at the wireless museum at Dulwich where we now have upwards of 50 sets connected and working ...
As you can see from the schematic, there is already scope for well over 100 outlets in the Display area (although Dual Standard set usually need two) and I've designed in enough spare capacity to quadruple the overall capacity if Peter feels there isn't enough!

By the way, when you see SHED on that plan, it might make more sense to you if you think in terms of 'Swiss Chalet'!

Quote:
Originally Posted by AC/HL View Post
If you get a chance, have a word with a friendly Cable TV engineer, or a ceased CTV customer. They use resistive splitters and they're a throw-away component to them.
<panto mode> Oh no they're not! </panto mode>

They are good quality inductive splitters which have much lower losses than resistive devices plus a very good isolation from output to output.

When planning how to split your Aurora's output, think in decibels.

The output is, as has been said, 6mV but this can also be expressed as +16dBmV. The absolute minimum input to a TV should be taken as 0dBmV (1mV) and the absolute maimum as +10dBmV (3mV) so planning for around +6dBmV (2mV) should keep any set happy!

Remember, when working in dB, the figures simply add or subtract, so calculations are simple.

Take the loss of a 2-way splitter as 4dB, a 4-way splitter as 8dB and an 8-way splitter as 11dB.

Cable losses, using CT100 type cable, varies between 20dB/100m at 862MHz down to around 5dB/100m @ 45MHz and 10dB/100m at 200MHz so, if your cable lengths are fairly short - up to 10m overall, say, the cable losses are small enough to be virtually ignored.

Taking these figures, an Aurora feeding one 8-way splitter will deliver signals between 5dBmV (Band I) and 4dBmV (Band III) - pretty much centre of the specified range) to up to 8 sets.

It couldn't be simpler for what I would imagine would be quite an impressive display for many.

Using a 2-way splitter in reverse as a combiner fed by 2 Auroras then fed to a 4-way splitter will comfortably provide Band I & III signals to up to 4 sets. It is only beyond this that you need to consider using an amplifier, which should go immediately after the combiner.
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