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Re: [TowerTalk] Antennas for SO2R station

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Antennas for SO2R station
From: Michael Tope <W4EF@dellroy.com>
Date: Mon, 1 Mar 2021 23:00:45 -0800
List-post: <mailto:towertalk@contesting.com>
Hi Jamie,

About 20 years ago, I helped build an SO2R setup at W6UE. At that time, we had mono band Yagi antennas for 10, 15, and 20 meters stacked on the same mast with ~7 to 10 feet spacing. We also had a 40 meter mono band Yagi on a separate tower. Marty N6VI built a really nice set of LMR-400 stubs for us that we installed right where the coax lead from each Yagi connected to the common port of the Radio1/Radio2 select switch. We put ICE-419 bandpass filters between each transceiver and the corresponding Alpha 78 amplifier.

As with others who have shared similar experiences, you could receive on one radio without desense while transmitting with 1500 Watts on the other radio as long as you stayed off the harmonic of the transmitting radio. We used various radios in the setup. Initially we ran a TS950SDX alongside a TS940S. Later on we used a pair of FT1000MP MK V's. In some instances the radios were setup for SO2R at one operating position. In other cases, we split the setup into a pair of one radio operating positions for doing multi-operator efforts in the SS contest.

Consider adding a set of stub filters to augment your bandpass filters, especially if you plan on running an amplifier and the power handling capability of the bandpass filters dictates that they have to be placed at the input of the amplifier. I think both W2VJN and K9YC have written good stuff on how to configure the stubs correctly.

Good luck. It's a real hoot when you get it working right.

73, Mike W4EF.........................

On 3/1/2021 10:20 AM, WW3S wrote:
I live on a small lot, 80x180, in a subdivision....I have a 50ft tower with a 3L Steppir on it.....I had planned on putting another Steppir 2L about 7 ft above the tribander.....BUT......my current SO2R setup I'm using a Hytower as the second antenna.....the rigs are a 7610 and 7300.....I have 5B4AGN bandpass filters on both rigs.....I'm already having interference issues between the rigs now, so I think moving a second antenna to the same mast is asking for more trouble. Just wondering if anyone uses 2 antennas on the same mast for SO2R? Also, is the 7300 maybe a problem? I heard that radio generates a lot of phase noise on TX, not so good in SO2R applications. Anyway, planning for some tower maintenance this summer, and looking for suggestions on optimizing the station for SO2R....
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