FM Radio Aerial Recommendations

[DMcMahon]

Can anybody please recommend a good indoor portable FM aerial (maybe desk/table top mounted) for use with vintage domestic solid state radios.

Additionally is there anything available that also would provide good reception for AM as well as FM.

Cost not important.

David

[paulsherwin]

Indoor aerials are always a last resort, with inherent problems and limitations.

Your best approach is to go for a cheap telescopic amplified dipole, or make one yourself. The amp is usually a simple one transistor affair, giving about 10-16dB of gain. There's no point in going for anything more exotic, as the indoor limitations will still be there.

You will need to experiment with different positions and alignments.

[DMcMahon]

Thank you Paul.

Any idea if the integral FM aerial on my JVC JR-S201L AM/FM Receiver as can be seen in the attached photo, is likely to have any amplification and would an amplified telescopic dipole aerial be likely to provide stronger signal/better reception, once best/optimum position/alignment is determined.

David

[Silicon]

Are you referring to the black plastic rod?

This is probably a ferrite rod used for medium and long wavebands only.

The internal switching inside the receiver will probably select the ferrite rod for AM, and the screw terminals for FM.

Do you have 75 and 300 Ohm terminals for the FM aerial?

[DMcMahon]

Yes I was incorrectly referring to the black plastic rod ! which as you say is the MW/LW ferrite bar antenna, a senior moment

Yes it has 75 and 300 Ohm connections as per attached photo.

David

[Radio Wrangler]

These things were often supplied with a folded dipole made out of ribbon feeder (2 wires separated by about a 12mm plastic ribbon. It was flexible and about an arms' span long. The idea was to pin it out on the wall behind the tuner. They worked moderately well and better than telescopic rods, if the direction of the wall was favourable.

David

[DMcMahon]

Yes I have one of those 300 Ohm twin wire T aerials, it came supplied with my Sansui R-50 Receiver a long time ago. It worked pretty well with the R-50 once a good position was found.

Just need to locate it, have not seen it for a long time.

David

[DMcMahon]

I see that many of the online 300 Ohm twin wire dipole T aerials are terminated in a male coax connector so I assume that some radios/receivers have coax connector for the 300 Ohm aerial as opposed to the 2 screw terminals that my JVC and Sansui have.

David

[paulsherwin]

The impedence mismatch only makes about 3dB difference, so it doesn't really matter with an indoor aerial, where other losses are likely to be much more significant.

[wd40addict]

In my den I have an indoor wired aerial feeding a valve Heathkit tuner, for ages I connected it though a balun plug. In theory this is correct, it matches the 300R odd of the aerial to the 75R input of the tuner, however results weren't that great. One day I tried connecting the aerial directly and it was much better! I suspect what's going on is that the aerial won't be a perfect 300, the tuner won't be perfect 75 and the balun is introducing loss anyway, add it all up and you're better off without it!

[DMcMahon]

Sorry Paul to be ignorant, where does the 3dB mismatch come from, are you saying that the coax connection even though it would plug into a coax connector on the radio, it is not 300 Ohms like the screw terminal connection ?

David

[majoconz]

The old TV 'rabbit's ears' with each rod pulled out to 750mm each leg with 300ohm ladder line to the 300ohm terminals on your tuner should work a treat.
I use mine for my micropower transmitter - works well.

[Mr 1936]

Hi

If made properly, what looks like just a coax plug on the end of the 300 ohm ribbon feeder incorporates a combined Balun and 300 to 75 ohm matching transformer. These use a tiny ferrite core with a few turns of wire on it, which is hidden inside the plastic moulding.

At one time you could buy these assemblies as a separate item, they had a couple of screw terminals to attach the ribbon feeder.

If made cheaply, there is no Balun, just a direct connection !

Historically, 300 ohm ribbon feeder was used in the USA for TV antennas, rather than the 75 ohm coax popular in the UK. As the USA was a good market for Japan from about the 1960's onwards, they adopted the same standard.

[DMcMahon]

That is very good input.

So if I understand it correctly a 300 Ohm ribbon T dipole aerial terminated in a co-ax plug (that contains the matching Balun) fits into the 75 Ohm coax connector on the radio/receiver, i.e. there is not a 300 Ohm coax connector on the radio to take a 300 Ohm aerial fitted with coax plug (without matching Balun).

David

[Herald1360]

Sounds about right!

Realistically, the positioning of an indoor aerial will have a much greater effect than exactly what type it is and how well matched or connected it is.

Picture rails are very handy mounting places if you're lucky enough to have them!

[simpsons]

David

Can we have a little more information on the premises the indoor aerial is going to be sited?

You have an enviable posting record on this site and so can assume that you are no novice to the subject.

Chris

[bikelectro]

Try your outdoor TV aerial if you have one, I pick up all local stations great with no noise. This is in a proper high quality separates system. If it works then replace your single wall socket with a double TV/FM duplexer combined one. It is not ideal but will often be as good or better than an indoor one

[DMcMahon]

Originally Posted by simpsons

David

Can we have a little more information on the premises the indoor aerial is going to be sited?

You have an enviable posting record on this site and so can assume that you are no novice to the subject.

Chris

Semi detached house with Radio/Receiver (s) normally in upstairs bedroom.

I was thinking of trying a proper FM outdoor aerial sited in the attic.

I am a relative novice when it comes to radio technology.

David

[DMcMahon]

Originally Posted by bikelectro

Try your outdoor TV aerial if you have one, I pick up all local stations great with no noise. This is in a proper high quality separates system. If it works then replace your single wall socket with a double TV/FM duplexer combined one. It is not ideal but will often be as good or better than an indoor one

Good idea I will try that.

My outdoor TV aerial cable does not connect to an aerial wall socket box and the aerial cable does not go down the wall cavity. The aerial cable enters the loft and goes down through my airing cupboard into a water pipe access area alongside a dummy chimney (dummy chimney originally for flue of gas back boiler but now for flue of gas fire).

In the loft I have previoulsy teed off the TV aerial cable to take separate cable runs into bedrooms, so fairly easy to connect the TV cable to radio in bedroom at least for testing.

David

[emeritus]

Dad's mid-1950's radiogram had an internal FM aerial consisting of strips of foil on the inside of one of the back panels, connected by a short length of 300 Ohm balanced feeder via a 2 pin plug with wander plug gauge pins. I used to use an old 405-line TV rabbit ears set-top aerial balanced on a beam in the loft, connected via 75 ohm co-ax terminated with two wander plugs with no balun and it worked fine.