[CQ-Contest] W3NQN Pass Band Filters

Tonno Vahk tonno.vahk at mail.ee
Mon Feb 10 10:47:05 EST 2003

Valeri, you will not regret that purchase! We did exactly the same for
ES9C/ES6Q M/M station. Those filters are incredibly efficient and the
attenuation graphs given by WX0B on his website are absolutely correct.

While now you are probably having interferences all over the bands, with
filters you will only be left with some harmonics on exact harmonic
frequencies. We have noticed that however good the filters and stubs are you
cannot eliminate those as for some reason they seem to regenerate themselves
in the antenna system. I have noticed it in all QTHs...

But it is very easy to stay off the harmonic frequencies by 5-10 KHz so they
will not be much of a problem.

----- Original Message -----
From: "Valeri Stefanov" <wally at el-soft.com>
To: <cq-contest at contesting.com>
Sent: Sunday, February 09, 2003 6:21 PM
Subject: [CQ-Contest] W3NQN Pass Band Filters

Hi Fellow Contesters,

We are seeking for advice.
The LZ9W contest team has reached the moment when we must do something for
interstation interference while operatiing M/S or M/M.
We are now going to order a set of 6 W3NQN single band 200W pass band
Having in mind that all 4 operating places for mini M/M set up are located
into a single room ( 4m x 6 m) and all antennas are relatively close to each
other within a diameter of just app 100m we are wondering if these filters
will help significantly to reduce interstation interference ?
During the last CQWW 2002 (SSB & CW) we operated without any filtering and
in spite of considerable intereference we have not lost even a single front
end :-))).

The 4 operating places for 2003 contest season are planned to be:

80m/10m - FT920 + Alpha 91b
20m - IC746 + ACOM 2000A
40m - TS940 + Alpha 91b
160m/15m - IC 756ProII + ACOM 2000A

Antennas are :  all WA3FET OWA yagies on 10,15 and 20m.

160m  - Inv. Vee ( app 50m away from all other antennas beside 10m ant)
80m - 2 el. phased Inv.Vees ( one element on separate Aluminum mast and
second element just 3m below 20m yagi on the tower supporting 20m yagi ,
both 80m and 20m antennas on the roof of a three stores small hotel)
40m - HB9CV yagi on separate tower app 40m away from other antennas
20m - 6 el. WA3FET on separate tower - 40m away from 40m ant and 10m ant and
30m away from 15m ant , one of 80m ant el just 3m below it .
15m - 6 el WA3FET on separate tower abt 45 m away from 40m and 10m ant and
app 30 m away from 20m ant.
10m - 7 el WA3FET on separate tower app 40m away from all other yagies and
25m away from 160m Inv.Vee .
We also have KT34A 10m below 10m yagi on the same tower.

If anyone is interested I may send him some pictures of these antennas, but
I hope my explanation is easy to understand.

So, those of you who operate in M/2 or M/M or M/S please comment on -  is it
worth to buy W3NQN filters to fight the interstation QRM ? Will it be
significantly reduced for these 500 USD we are going to spend ?

73's de Wally LZ2CJ(LZ8T) team member LZ9W & YM3LZ
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