UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Components and Circuits

Notices

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.

Reply
 
Thread Tools
Old 17th Oct 2019, 7:15 pm   #1
alanworland
Heptode
 
alanworland's Avatar
 
Join Date: Feb 2011
Location: Southend, Essex, UK.
Posts: 587
Default 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
alanworland is online now   Reply With Quote
Old 17th Oct 2019, 7:29 pm   #2
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 7,753
Default 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.
G6Tanuki is offline   Reply With Quote
Old 17th Oct 2019, 7:36 pm   #3
Julesomega
Hexode
 
Julesomega's Avatar
 
Join Date: Dec 2012
Location: Stockport, Greater Manchester, UK.
Posts: 435
Default 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
__________________
- Julian

It's good here
Julesomega is offline   Reply With Quote
Old 17th Oct 2019, 7:38 pm   #4
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 7,194
Default 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.
__________________
Frank
Nuvistor is online now   Reply With Quote
Old 17th Oct 2019, 9:12 pm   #5
alanworland
Heptode
 
alanworland's Avatar
 
Join Date: Feb 2011
Location: Southend, Essex, UK.
Posts: 587
Default 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
alanworland is online now   Reply With Quote
Old 17th Oct 2019, 9:20 pm   #6
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 3,927
Default Re: FM aerials

I'm not a fan of passive splitters. I use powered distribution amps by labgear.
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is online now   Reply With Quote
Old 17th Oct 2019, 10:01 pm   #7
Sideband
Dekatron
 
Sideband's Avatar
 
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 5,427
Default Re: FM aerials

Quote:
Originally Posted by stevehertz View Post
I'm not a fan of passive splitters.
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.
__________________
On Spike Milligan's headstone......I told you I was ill...
Sideband is online now   Reply With Quote
Old 17th Oct 2019, 10:15 pm   #8
paulsherwin
Moderator
 
paulsherwin's Avatar
 
Join Date: Jun 2003
Location: Oxford, UK
Posts: 18,535
Default 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.
paulsherwin is online now   Reply With Quote
Old 17th Oct 2019, 11:47 pm   #9
winston_1
Hexode
 
Join Date: Oct 2012
Location: London, UK.
Posts: 306
Default Re: FM aerials

Quote:
Originally Posted by alanworland View Post
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
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.
winston_1 is offline   Reply With Quote
Old 18th Oct 2019, 12:01 am   #10
Skywave
Dekatron
 
Skywave's Avatar
 
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 6,478
Default 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.
__________________
Never act on your first idea. Like solving a crossword clue, a better idea arrives tomorrow.
Skywave is offline   Reply With Quote
Old 18th Oct 2019, 12:04 am   #11
Skywave
Dekatron
 
Skywave's Avatar
 
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 6,478
Arrow Re: FM aerials

Quote:
Originally Posted by winston_1 View Post
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.
Agreed, but occasionally installing a dist. amp. can be a lot easier than replacing the aerial.

Al.
__________________
Never act on your first idea. Like solving a crossword clue, a better idea arrives tomorrow.
Skywave is offline   Reply With Quote
Old 18th Oct 2019, 8:12 am   #12
stevehertz
Dekatron
 
stevehertz's Avatar
 
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 3,927
Default Re: FM aerials

Quote:
Originally Posted by winston_1 View Post
Quote:
Originally Posted by alanworland View Post
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
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.
The issue appears to be not one of a lack of 'amplification', but choosing the 'best' way to connect that aerial to two pieces of equipment. Passive splitters are notorious for being dodgy. If they're resistive they reduce signal level, but at worst they may be just a three way wire link concealed in a plastic moulding thus messing up impedance matching. True, even the latter version may 'work', but many including myself prefer things to be more theoretically sound. It depends which camp you fall into and I concede that investing a couple of quid on an eBay passive splitter may well be worthwhile especially if you're just listening to strong local stations.
__________________
A digital radio is the latest thing, but a vintage wireless is forever..
stevehertz is online now   Reply With Quote
Old 18th Oct 2019, 8:53 am   #13
Hartley118
Octode
 
Hartley118's Avatar
 
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 1,409
Default 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
__________________
BVWS Member
Hartley118 is online now   Reply With Quote
Old 18th Oct 2019, 9:03 am   #14
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 7,194
Default 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.
__________________
Frank
Nuvistor is online now   Reply With Quote
Old 18th Oct 2019, 10:59 am   #15
TrevorG3VLF
Octode
 
TrevorG3VLF's Avatar
 
Join Date: Apr 2011
Location: Matlock, Derbyshire, UK.
Posts: 1,258
Default 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.
TrevorG3VLF is offline   Reply With Quote
Old 18th Oct 2019, 12:23 pm   #16
GRID LEAK
Triode
 
Join Date: Jun 2009
Location: Lancashire, UK.
Posts: 41
Default 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
GRID LEAK is offline   Reply With Quote
Old 18th Oct 2019, 12:42 pm   #17
John_BS
Octode
 
Join Date: Dec 2008
Location: Wincanton, Somerset, UK.
Posts: 1,050
Default 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.
John_BS is offline   Reply With Quote
Old 18th Oct 2019, 12:56 pm   #18
alanworland
Heptode
 
alanworland's Avatar
 
Join Date: Feb 2011
Location: Southend, Essex, UK.
Posts: 587
Default 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
alanworland is online now   Reply With Quote
Old 18th Oct 2019, 1:15 pm   #19
Scimitar
Heptode
 
Scimitar's Avatar
 
Join Date: Oct 2015
Location: Gloucestershire, UK.
Posts: 524
Default Re: FM aerials

Quote:
Originally Posted by alanworland View Post
Just been and purchased the Labgear unit which looks well made, 2 year guarantee and 15dB of gain.
The Labgear brand is one that the trade used to know and trust. They decided that to enhance profits, they would sell into B&Q at prices that meant that their retail was below normal trade price. Result was that the trade stopped buying and Labgear bit the dust.

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.
Scimitar is offline   Reply With Quote
Old 18th Oct 2019, 1:27 pm   #20
Nymrod121
Octode
 
Nymrod121's Avatar
 
Join Date: Apr 2012
Location: Worcestershire, UK.
Posts: 1,614
Default 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
Nymrod121 is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 7:51 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.