Eddy VE3CUI wrote:
>Hi George,
>
>I'm curious as to how the results might compare, if one were to simply place a
>series-connected coil & capacitor wave trap (resonant to the BC station's
>frequency, of course) to ground at the receiver input...? Was that tried prior
>to the inclusion of the high-pass filter?
>
>The wave trap could be made even more effective if one were to place a second
>parallel-tuned trap in series with the antenna lead, and installed between the
>receiver & the series-tuned trap...
>
>~73~ de Eddy VE3CUI - VE3XZ
Hi Eddy
You are correct, but obviously this is not the best approach for multiple
broadcast stations.
When I first built my remote station there was a high power AM station with an
8 element
array beaming straight at it from about 1km away. This made receiving difficult
as it was
inducing literally volts onto my 260' vertical.
I built a simple elliptic function filter with a null at 790kHz and high
pass-band ripple. This
provides better than a 60db null across the modulated bandwidth of the BC
station and
negligible attenuation on 160m - but very variable attenuation across the
remainder of
the broadcast band. The filter has only 3 capacitors and one inductor.
I think this is a better approach than just a series tuned circuit as all
parameters
(including the necessary filter complexity) are under the designer's control.
Now the other BC station has closed down and I have no AM stations within 150km
-
by far the best solution!
73 Roger
VE3ZI
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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