SO2R Antenna Band Multiplexing

Continuing our discussion of Single Operator Two Radio (SO2R) station design brings us to the topic of antenna routing.

Previously we discussed SO2R gear arrangements which have two antennas connected to two radios, one antenna for each radio.

If all you have are two antennas for your two radios then there really is no point in putting in a matrix to allow either antenna to route to either radio.

However, let’s assume you do have a pressing need to multiplex the antennas and use this as an evolutionary step in our series of posts.

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SO2R Antenna Band Filtering

Continuing our discussion about SO2R technical discussion brings a focus to the concerns of cross band interference between your two radios.

Having one transmitter spewing energy at full power while trying to listen on the other radio’s receiver is daunting. Unless you have an Elecraft K3, your radio’s ability to perform adequate band pass filtering is probably not sufficient for the 2nd and 3rd harmonics from the transmitter resulting in severe de-sense of the receiver signal chain.

Orienting the antennas to minimize their interaction will help. If you are lucky you may well achieve good isolation between at least some of the cross band combinations.

To help radios avoid this interaction, a few manufacturers have products which provide excellent band pass filtering.

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Single Operator 2 Radio SO2R

In my many years as a ham, I somehow missed the whole topic of the Single Operator Two Radio (SO2R) technique for amateur radio contesting. I pulled up a few YouTube videos showcasing the great operators using this technique and convinced myself SO2R is interesting enough to research.

The ability to add a bit more excitement to those late contest constant CQs with an additional radio looking for other contacts, especially new multipliers, is inviting.

There are many resources on the Internet about why to do SO2R. I invite the reader to explore these resources. We will review a couple key concepts on why to do SO2R and then dig in deep to some technical approaches.

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