Hi Mike,
Just a few thoughts: Was you stub open or shorted? 1/4 wave shorted 40m
stub should produce about 25-30 db nulls on 20m & 10m, but not 15m. Also
may want to verify the tuning of the stub - it may be nulling some frequency
out of the band. How close (how much coupling) are you getting between the
antennas, it may also be that a single stub is insufficient attenuation, and
your receiver AGC may be masking the attenuation that you are getting.
Hope these thoughts help.
Matt
KM5VI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Mike
Smith VE9AA
Sent: Monday, September 07, 2015 5:36 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Coax STubs for SO2R
I've seen the K2TR stubs, K1TTT page and have recently bought the FB book by
W2VJN
Today, for a change, I had a little spare time so built 2 stubs, but lets
just concentrate on one.
It was supposed to be for the 40m transmitter.
I roughed out the length, attached a T and my antenna switch (a la VA2UP
method) (which I'll only use for stubs, trimmed it with my AA-230pro
and when it's inline (parallel to my primary antenna switch) I see no
difference at all on 20m or 15m on my 2nd receiver when the stub is in or
out of line
NONE. Like, not even a titch ESP hopeful. (hi)
I presume this is a type 1 stub (shorted 1/4WL type, x velocity factor)
Thinking I had done something wonky, I made another stub from different
coax..same result.
Anyone been down this road?
Too close to rig?
Interaction from my T and 2nd antenna switch? Gremlins? Wrong method using
the AA-230 pro maybe? I am close to that 23' mark.
de Mike (SO2R hopeful) VE9AA
Mike, Coreen & Corey
Keswick Ridge, NB
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