[W126 Coupe] Dodgy radio reception

[Shayegan, Richard]

The funny thing is, there are two stations that it works better low:
94.7 and 100.3. They also have a 100.3 in NC, yet for that one, and
every other station in the Charlotte, NC area I get the best reception
with it all the way up. In DC, 100.3 and 94.7 get the best reception
with the antenna low, not all the way low, but maybe 2/5 of the way up.

Richard

 

________________________________

From: mbcoupes-bounces at mbcoupes.com
[mailto:mbcoupes-bounces at mbcoupes.com] On Behalf Of
Ken.England at ipaustralia.gov.au
Sent: Wednesday, March 16, 2005 10:42 PM
To: Mercedes Coupes Mailing Lists
Subject: [W126 Coupe] Dodgy radio reception 

 


I get better reception by lowering the antenna almost all the way. I
wonder why that is. (Richard) 

 I presume you mean on FM.  If there is a break in the rather fragile
coaxial cable from the antenna the radio may be picking signal mainly
from the coax cable outer conductor and when up, the antenna opposes the
signal - because it is out of phase on some frequencies.  If AM
reception also is weak on stations only 15 miles away this is probably
the cause.   
  
The OEM coax on my '83 had a break in the center conductor which was a
single thin wire.  FM reception was dodgy and AM reception poor. I
replaced it with some coax I had lying about, probably was the 50 ohm
RG58U as the 75 ohm TV stuff is thicker and less flexible.  The antenna
connector  on the OE Hirschmann system is unique, at least it was on
mine.  None of the people in the electronic shops I took it to had ever
seen one before.  At the back of the radio the OE antenna plug
incorporates a series capacitor which apparently helps to "tune" the
antenna.  So to replace the cable you will need to retain these two
plugs and that means two coaxial cable joiners.  The TV type are
adequate, but get quality ones if you can find them.  Alternately put a
capacitor in series with the centre conductor at the antenna end and
dispose of the OE antenna plug.  As far as I know most car r! adios are
not set up for a capacitor in the line, so if you replace the Becker you
probably won't need the capacitor.   MB just has to be different. 

You can run the new cable along the inner door sills if it's too much
trouble to get it through under the seat.   

Ken England

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