Hi Tom,
The W3AO Field Day team has used multiple transmitters in the
same band for more then 20 years with no trace of interference at all.
We often have four transmitters on the same band (CW, SSB, digital
and GOTA).
We do not use any fancy filtering. The key to our success is using
horizontally polarized antennas installed end-to-end. For example,
on 20 meters we use four Yagis installed in a straight line with
nearly 300 feet of spacing between the tips each Yagi.
The same principle is applied with dipoles. on 80 meters we use
three dipoles installed in a straight line with about 300 feet of
spacing between the tips of each dipole.
Its important to use transmitters with clean phase noise characteristics.
Some of the early synthesized transceivers are unusable such as the
Kenwood TS-450S. Many other common transceivers such as the
FT-1000MP, FTdx5000 and K3 are completely interference free.
Some of the serious DX contesters also have the capability to
operate in band with 1500 watts. A clean transceiver, a very clean
amplifier (very low IMD), and widely spaced antennas with proper
antenna orientation are keys to success.
Of course DXpeditions have also successfully conquered these same
issues for years.
73
Frank
W3LPL
----- Original Message -----
From: "Tom Hellem" <tom.hellem@gmail.com>
To: CQ-Contest@contesting.com
Sent: Saturday, March 18, 2017 1:54:50 AM
Subject: [CQ-Contest] SSB & CW On Same Band
Has anyone successfully run 2 stations on same band, SSB &CW,
without interference between the two? For example, FD or IARU.
We have tried it several times and have always ended up with moderate
to severe interference to the point that one station had to qsy to
another band.
Obviously (I think) the filters that are in common use like Dune Star, ICE,
NQN, etc. don't work because they are band pass filters. But has
anyone designed/built a filter with sharp enough roll-off to make this work?
Or, would a pair of K-3's , etc. fit the bill?
Would love to hear from people that have made this work for them, and how
they did it.
73
Tom
K0SN
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