Hi,
we are three amateurs radio with different transceivers,
different antennas and ground systems but all with the
same problem : moderate to strong interference to the video of the
TV channel B ( 61/68 MHz ) when we transmit on 21 MHz
band ( 100 W ) ;in my case, the TV antenna is directly
connected to the TV Set ( no preamplifier on the feeding
line being the imput signal 1mV ).
Connecting a Spectrum Analyser to the receiving TV antenna
I see the third harmonic that interferes with TV signal (it is
~ 33 dB less ); connecting a Drake low pass filter the armonic
on HF cable decreases of 45dB but on TV cable:it has ,more
or less , the same amplitude .
I tried a TG-4 Line Isolators but nothing has changed, so I
have no other ideas.
One of the test I tried it has been to use a dummy load instead
of antenna (Explorer 14 )and the TV channel was ok;the strange,
in this case,is the behavior of the low pass filter:it does not work;
all the armonics at the dummy load terminal keep the same
amplitude with or without it.Using a signal generator instead of the
TX (Mark V) it works correctly cleaning all the armonics
Can you help me ?
Thanks
Aldo IK2ANI
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