mw/lw antennas and reception

[pioneer]

hi,
hope dont mind me asking a few questions re mw/lw antennas and reception.
i have an old 70s radiomobile type 80 car radio, mw and lw only.
im wanting hook up an antenna to this, but not sure where to go, not looking to dx but just rx a few stations on those bands.

im a bit of a vintage radio collector hence this radio, and would dearly love to put it to use.

now when i connect a short wire of around 10ft, well it was actualy coax i used, if i wire the plug up, ie inner and outer to the aerial plug then plug into radio i get nothing, as if its muted.
now i found by accident that if i just connect the inner of coax and not the braid, it works, can hear stations, but then touch the braid to outer of antenna socket,nothing.
any ideas.
so, works fine with center connected, but touch the braid to earth i presume,nothing.
also, would a longer length of cable make any difference or improvement over the short 10ft length i use at present.
any gain in going for longer length, say 100ft over a 10ft length, as with 10ft i can pick up quite a bit.

another thing i thought, cars have radios with mw, and use the cars antenna, with decent results, ok not dx, but not after that.
so if i had a car antenna hooked up, would i get same,or similar results.

many thanks guys.
mark.

[daveB]

If I've read what you have written correctly, the reason you don't get any signal with the braid connected is because it shields the centre - which is what coax is supposed to do. You need to attach an unshielded wire to the end of the length of coax. A 3ft length should do quite well. If you run the coax away from noise sources you will get better reception. Of course it wouldn't be consider a 'proper aerial but I gather you don't want flags, pennants, shielded loops - just something to get the radio working.

[John Faulkner, Skegness]

If I've read what you have written correctly, the reason you don't get any signal with the braid connected is because it shields the centre

No, the braid, connected to the inner, would work as an antenna, effectively becoming one wire. That's how the FM loop antennas were constructed, using coax with the inner and the braid shorted together.

[pioneer]

thanks guys.
no not looking for another antenna, enough up as is.
just something get it working will do.

i had a spare length of coax lying around hence used that.
with the centre, of the coax connected to radio, works ok, but touch the braid against other side of plug,nothing, just kills it...

so no benefit running a longer wire over the 10ft piece i use at moment then?