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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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17th Oct 2019, 7:15 pm | #1 |
Heptode
Join Date: Feb 2011
Location: Southend, Essex, UK.
Posts: 802
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FM aerials
I have quite a good FM aerial in the loft which supplies my tuner in the lounge, I also have another system set up in my 'study' also with an FM tuner the signal for this I think was split from an external TV aerial.
I would like to take my study signal also from the loft FM aerial. What would be the 'best' way of doing this? Run the cable direct to the aerial junction box or break into the existing cable with a splitter? Alan |
17th Oct 2019, 7:29 pm | #2 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,951
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Re: FM aerials
The best thing would be to use a 2-outlet "distribution amplifier" - something like this:
https://www.screwfix.com/p/labgear-l...mplifier/3632x to divide the signal from your existing loft-aerial and feed the two tuners. |
17th Oct 2019, 7:36 pm | #3 |
Nonode
Join Date: Dec 2012
Location: Stockport, Greater Manchester, UK.
Posts: 2,085
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Re: FM aerials
I split inside the house, from a rooftop antenna, with a 4-way passive splitter, giving plenty of signal to each socket
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17th Oct 2019, 7:38 pm | #4 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
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Re: FM aerials
G6Tanuki suggestion is the best.
However if you don’t want to do that you will need to use some form of splitter, you cannot just connect two coax cables to the aerials connection box. Two port Splitters are three types, inductive with losses of 3db, resistive with losses of 6db and a straight through type which shouldn’t be on the market and can cause all sorts of problems. The inductive type will halve the signal to the outlets, resistive even more, straight through will produce standing waves and perhaps suck out at certain frequencies. It all depends as well on how much signal you have to start with.
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Frank |
17th Oct 2019, 9:12 pm | #5 |
Heptode
Join Date: Feb 2011
Location: Southend, Essex, UK.
Posts: 802
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Re: FM aerials
Thanks guys, not sure what sort of signal levels I have but lounge tuner seems happy with what it gets but I guess halving it, at best, is asking for trouble?
That Labgear unit sounds quite the business, plus I have a £10 voucher! Alan |
17th Oct 2019, 9:20 pm | #6 |
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
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Re: FM aerials
I'm not a fan of passive splitters. I use powered distribution amps by labgear.
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17th Oct 2019, 10:01 pm | #7 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,548
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Re: FM aerials
Quite. They might be OK for a 'quick fix' or for a temporary arrangement but the best ones are the active type (distribution amplifier) that feed a good signal to two (or more) outlets.
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17th Oct 2019, 10:15 pm | #8 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,786
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Re: FM aerials
Beware of very cheap passive splitters, which are effectively just two sockets connected to a plug. They do have some uses where signal strengths are high, but should be avoided if any reception problems exist.
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17th Oct 2019, 11:47 pm | #9 |
Hexode
Join Date: Oct 2012
Location: London, UK.
Posts: 497
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Re: FM aerials
I very much doubt if an amplifier is required. Try a passive splitter first. A much better way of getting more signal is a better aerial than an amplifier.
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18th Oct 2019, 12:01 am | #10 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
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Re: FM aerials
If you are going to buy and fit a dist. amp., buy one with more that 2 outputs. Sometime in the future you may find you have a need for a feed to another set - or more. After all, you really only want to do this job once and the price difference between a 2 and a 4 - or even a 6-way - is usually disproportionately small.
Al. |
18th Oct 2019, 12:04 am | #11 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
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Re: FM aerials
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18th Oct 2019, 8:12 am | #12 | |
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,809
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Re: FM aerials
Quote:
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18th Oct 2019, 8:53 am | #13 |
Nonode
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 2,196
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Re: FM aerials
I’m cautious about antenna amplifiers on FM radio. Effectively the (hopefully) carefully designed low noise low intermodulation front end of your tuner is being replaced by an unknown low cost preamp that may or may not have a linear performance.
In this part of the country we’re afflicted on FM by background ‘birdies’, presumably co-channel interference from the continent. Linear front end performance is important for minimising intermodulation from such unwanted signals and I’ve found experiments with an aerial booster do seem to make birdies worse. My recipe is a high gain outdoor antenna with any subsequent distribution on the way to the tuner being entirely passive. I’d be interested to hear of others’ experience. Martin
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18th Oct 2019, 9:03 am | #14 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
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Re: FM aerials
A good aerial is always a better option but as been said not always practical. Cross mod can be a problem but for most of us can only be tested by trying it out.
Alan could try a passive splitter first and decide if it suitable, we have no idea of the tuner's performance, it may be OK with less signal or not. There is also the possible interaction between both tuners with a simple splitter, a resistive splitter will give more isolation but at the expense of greater attenuation. It’s a case of try it and see.
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Frank |
18th Oct 2019, 10:59 am | #15 |
Rest in Peace
Join Date: Apr 2011
Location: Matlock, Derbyshire, UK.
Posts: 1,378
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Re: FM aerials
I cannot get info the loft to see exactly what I have however the amplifier has FM and TV inputs and four outputs, TV or FM can be taken from any output. I use three outputs with one passively split for FM and TV at the same location.
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18th Oct 2019, 12:23 pm | #16 |
Triode
Join Date: Jun 2009
Location: Lancashire, UK.
Posts: 46
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Re: FM aerials
If access to your loft isn't problematic , I would install a separate aerial to feed your 2nd system. Simples.
Regzrds. John |
18th Oct 2019, 12:42 pm | #17 |
Octode
Join Date: Dec 2008
Location: Wincanton, Somerset, UK.
Posts: 1,757
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Re: FM aerials
There are two types of "passive" splitter:
a) resistive (6dB loss, 6dB isolation between outputs), and b) hybrid, about 3dB loss input-to-each-output, c 20dB isolation between outputs (minimises any LO leakage from one tuner getting into the input of the other). Normally the hybrid designs are broadband, have f connectors and are housed in die-cast zinc cases. |
18th Oct 2019, 12:56 pm | #18 |
Heptode
Join Date: Feb 2011
Location: Southend, Essex, UK.
Posts: 802
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Re: FM aerials
Thanks for your comments!
My FM aerial is quite a large beast (can't remember what it is!) and luckily our loft is orientated in such a way that it fits in the loft shape well and points in the correct direction and due to 'stuff' a second is not really an option. Just been and purchased the Labgear unit which looks well made, 2 year guarantee and 15dB of gain. Going to install later but unfortunately the end over my study is quite well stuffed and will require some labour to get to the cabling! My lounge tuner is a Rotal RT-02 and my study tuners are Quad FM3 and FM4 Alan |
18th Oct 2019, 1:15 pm | #19 | |
Heptode
Join Date: Oct 2015
Location: Gloucestershire, UK.
Posts: 719
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Re: FM aerials
Quote:
One of the worst brands, even worse than Maxview is Philex. Many people realised that this was the case and went elsewhere. So then Philex bought the Labgear brand name and started passing their "budget" goods off as quality trade class items. An FM aerial does not need a distribution amplifier unless you are trying to resolve signals down in the noise. On any decent aerial installation, 3.5dB loss from an inductive splitter will never be noticed. If it is, then the aerial system needs sorting. |
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18th Oct 2019, 1:27 pm | #20 |
Nonode
Join Date: Apr 2012
Location: Worcestershire, UK.
Posts: 2,039
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Re: FM aerials
Alan, being as your location is shown as Southend then your nearest main VHF-FM station is Wrotham ... so on the assumption that your antenna is aligned thereon, try using a simple resistive splitter as a first step. There should be sufficient signal to meet the requirement of two sets but again this presupposes short cable runs using good-quality coaxial cable. Consider this as a 'try before you buy' commercial distribution amplifiers etc.
Having said all that, if you have an existing or future need to listen to stations further afield then 'the case is altered' Best wishes Guy |