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[TowerTalk] stubs for the SO2R setup

Subject: [TowerTalk] stubs for the SO2R setup
From: Felipe Ceglia - PY1NB <>
Date: Mon, 18 Aug 2008 22:30:24 -0300
List-post: <">>

I am trying to make a set of stubs to be used on my SO2R station setup.

Those stubs should be plugged to a six pak box.

When I measure the 1/4 wave shorted 40m stub, plugged directly on the
MFJ-259, with a dummy load paralelled by a tee connector, I can see the
nulls on 14 and 28mhz.

When I plug that stub and that very dummy load on the six pak 40m port,
things change. Nulls go to 12.9mhz and 24.9mhz.

The obvious explanation is that the length of cable between the amp
output and the six pak input is being added to the stub, right?

If so, also seem obvious that I should have the same length of cable
between both of the amps and the six pak, right?

If so, I should take this length into account, and things will change if
I turn the amplifier online, offline, right?

If so, how can I deal with it in situations where I have multiple stubs?
For example: on 40m, I plan to have 2 1/4 wave shorted stubs nulling 14
and 28mhz, and the 1/6 + 1/12 wave for nulling 21mhz

If so, I have quite a terrible problem in hands.

73 and thanks in advance for your advice,

Felipe - PY1NB


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