[CQ-Contest] W3NQN Bandpass Filters (Was: Re:419bandpassfilters..
jukka.klemola at elisanet.fi
Mon Apr 2 00:27:30 EDT 2007
>Jukka, 10 m ICE BPF has only 16 db attenuation on 15 m. Even worse is
only >11 dB attenuation of 15 m ICE BPF of 10 m signals. Your antennas
are >obviously spaced enough.
>73 de Mario, S56A, N1YU
I have a 4o4o4 on 10m, and a 4o4 on 15m on both towes, total 10 yagis
The closest spacing on both towers is maybe 2m or so.
That is 6 to 7 feet.
I think my antenna spacings are "maybe" too short.
In addition to ICE filters, I use stubs, K2TR design.
The stubs are made of 1/2" hardline.
I have no 15 to 10m nor 10 to 15m problems.
My improvement wish is to attenuate harmonic from 80CW to 40CW, 40 to 20
CW+SSB and 20 to 10 CW+SSB.
My thinking is these harmonics will not really help if I change to NQN
because the harmonics are created in the amps.
However, if I use only FT1000MP radios, the level of harmonics is bigger
than compared to harmonics using amps and all the filtering.
On 15/10m, if I remove the ICE filters using amps, the only phenomena I
get is wideband phase noise from band to band.
ICE filters attenuate enough so the phase noise goes below the noise
Of course the stubs effects on adjacent bands help a lot by K2TR design.
At least in my case ICE filters are good enough on those two bands.
Budget contesting is !
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