In a message dated 03/05/98 16:31:24, Tennant@t-online.de writes:
<< I have noticed that although the tower reception is clear and I have no
interferance at all I sometimes cannot hear other airplanes, even when we are
within one mile of each other. Also, although the reception in the plane is OK
I notice that my transmission range is only about 10 >>
10 miles is pretty poor for line of sight - ground stations mostly put out
much more power than airborne sets, which would account for not receiving
closer airplanes. It would appear you have something significantly wrong
probably on the antenna side. You could try running the set on the ground
with a temporary antenna with a different and shorter coax. assuming you have
a local airfield or VOR with ATIS.
VSWR's can be quite high (2 to 3) before serious transmission loss sets in.
They are bad news for output transistors though. The long length of cable to
the fin-mounted Europa antenna raises some other problems. Firstly there will
be more loss if it is not good quality cable - secondly if mismatched and with
low loss cable, the VSWR can have more than one resonance peak within the
airband. If one of these is sitting on your favourite frequency than you will
get poor performance.
So as Andrew W says, you need the help of a radio ham with a VSWR meter. This
reminds me of another feature I have noticed. The squelch on amateur band
receivers (at least in UK) works backwards with respect to that on airband
sets. So be careful you are not squelching your signals off
Graham C G-EMIN
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