During the test flying programme of G-OBJT it became apparent that although the
radio worked perfectly at the lower end of the VHF band, when we selected
frequencies
above 125.0 ground stations were having difficulty in receiving us.
I borrowed a Bird watt meter today and came up with some rather bizarre results.
The radio (Walter Dittel) delivered 5 1/2 watts throughout the range into
a dummy load (50 ohms), but as soon as the Europa half wave dipole aerial was
used very high readings were obtained at either end of the spectrum (11 watts
at 118.0 and 9 watts at 136.0) but down to 3 watts between 126.0 and 130.0. Can
anyone explain this and suggest a cure. I used a quality VSWR meter during
production of the antenna and obtained reasonable gain figures.
Brian Tarmar - G-OBJT Trigear - test flying complete and awaiting a full
permit(
subject to a working radio!)
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