[W1SMH] FD RFI

[Charles Morrison]

Ernie
These are typical single site inter-station mitigation steps taken at
multi-operator contest stations, many of which I’ve implement at my station
and others over the years. Several of these concepts were used @ SMH Field
Days during my time with the club in the late ‘80’s and early ‘90’s on the
circle at WWI park.
We used antenna separation, antenna aiming and nulls to control near-field
issues, transmit stubs at the transmitter.

Bandpass filters were higher tech back then and designs & products were not
as available as they have since become.
The triplexes are newer products to the ham market that were not produced
back then either.
Ultimately re-claiming the tens of decibels that are preventing the
receiver from hearing cleanly down to the noise floor requires multiple
solutions at the legal limit. At 100 watt levels simply turning off RX
preamps and noise blankets and/or adding some attenuation can prevent a
receiver from overloading.

-Charlie N1RR


On Tue, Jun 30, 2026 at 9:08 AM EKlawitter via W1SMH <w1smh at mailman.qth.net>
wrote:

> Lots of articles on cosine interference at Field Day.
>
> Generally,
> * separate antennas
> * k3s, Yaesu, kenwood NO, NADA ICOMS,  big Elecraft pitch
> * widely spaced antennas, in our case around the yard perimeter not
> crossed  etc, longer runs of coax
> * band pass filters
> * tuning stubs on the antennas
> * duplexers.
> Sent from my iPad
>
> KC1BOO, Aka Crash
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