[Moon] filters
M. Watanabe
jh1krc at syd.odn.ne.jp
Fri May 27 05:13:43 CEST 2016
Hi Phil,
What solution did you find to the TVI?
I am interested to know it.
A simple cavity filter of a quater-wl might be the best
solution for the selectivity and low loss, but it is bulky.
Two stage of a helical cavity filter, a finger-tip size, may
reduce 20dB of 432MHz. Insertion loss would be 4-5dB.
A coax stub notch may be the best for the second/third, or
more, of the harmonics, but a notch has a wide slope around
the notch frequency, so it is not a propper choice for the
filter for a near-by frequency.
Mike JH1KRC
---- Phil - FR5DN via Moon <moon at moonbounce.info> wrote:
>
> Hello All,
>
> After several years, i'm back on 70cms EME. Tks to all who helped and
> gave me energy and support. They will recognize themselves here. Tks guys!!
>
> The array (4x21) is low on the ground compared to before (about 3m
> instead of the 7m of the 8 yagis before).
>
> I have some tvi troubles around now...
>
> The digital tv qrg is 482Mhz here...
>
> Neighbour's antennas are some 30m from array. I need a tv filter to be
> connected to the tv system.
>
> I have tried several solutions from notch to highpass+notch, but i get
> too much attenuation on 482... and when ok on 482, not enough
> attenuation on 432.
>
> If you have any simple effective design with standard components, i am
> taker! Or maybe some effective low cost commercial solution.
>
> Reply offlist so not taking much bandwith pse.
>
>
> Waiting to work you off the moon!
>
> Vy73 - Phil - FR5DN
>
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