Re: Tube Hi-Fi directional AM antenna?

Gary Kinsman


Picking up two stations on the same frequency on FM is a function of the capture ratio, not selectivity. The lower the capture ratio, the better an FM tuner will be able to separate two FM signals on the same frequency. The signals have to be different in strength by at least the capture ratio (which is measured in dB) in order to do this. As Gabe pointed out, selectivity pertains to separating stations on adjacent frequencies, not the same frequency. Since it's probably not easy or practical to modify an FM tuner to improve the capture ratio, a directional antenna, possibly combined with variable attenuation, may be one solution.


--- In ultralightdx@..., "Lee" <leo1949uk@...> wrote:

If you`re receiving two FM stations on the same frequency then it IS
selectivity... you need attenuation... try soldering a resistor in
line with the centre core of the antenna coax - try 1kilohm to
2megohm! or a 2meg potentiometer (not advisable) if using twinfeed
then a resistor on both lines, keeping the feed balance correct.

Then you might winkle some DX from the gaps.

In europe, there are stations EVERY 100khz..very a selective
receiver is paramount.



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