Ferguson FRG 120D aerial help

[misterminibus]

I just can't get a signal in dab mode and need to fit an outside aerial but i'm not sure if the telescopic aerial on the side comes off as I can't get it to move or have a socket with walls thin enough to undo the nut has anyone removed this aerial ?

Also,
I have been looking to buy an outside aerial and the diapole sort has dab in the wording but not the loop one yet I prefer the loop one which just says vhf and fm but surley an aerial is just an aerial for reception only isn't it as there is no coil or anything needed to transmil on a certain frequency.

I would appreciate any help

 

[rolfw]

DAB is vertically polarised, whereas most VHF signals are horizontally polarised. The little omnidirectional FM antennae are no good for DAB, they have no gain and are designed for horizontal use, you need either an omnidirectional DAB antenna if you are in a good reception area, or a multielement version for lesser areas, see this page for some examples.

Not sure that many of these DAB portables have the facility for an external aerial input.

 

[misterminibus]

My friend has just been to screwfix and bought this for me, so its no good then ?

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331867&ts=77060&id=52645

but this one is ??

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331867&ts=77060&id=40830

I think you may just be right about the telescopic antenna I just cant get it off, if I could I would replace it with a tv style female plug.
Does a dab radio use both the inner and outer coax, IE antenna and groundplane or just the inner coax, in other words could I just solder the inner coax to the telescopic aerial and it would work 100% ?

 

[rolfw]

No, it doesn't work like that, you will also find that the onboard antenna is probably 300ohm and the external is 75ohm, so you would need a balun.

Those little circular antennae are not even very good for FM.

 

[misterminibus]

so this would not work

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331867&ts=77060&id=40830

with just the inner coax soldered on?
300ohm and the external is 75ohm,the less the ohms the worst it recieves?
so whats a balun.?
God this is complicated in comparison to anologue...

 

[rolfw]

You can try it, but I don't think it'll work. A balun is what converts the 300ohm to 75ohm.

 

[Llew]

The radio may well have a balun already between the rod aerial and the receiver's first stage to match the 300 ohm impedance of that aerial, it depends on the impedance of the input (may be AC coupled).

As Rolf suggested, a case of trying it and see if there is any impovement.

Llew