Hello!
I have been preparing coaxial stubs for an overseas M/S contest operation, and
at first it seemed like I was going to have to change the stubs manually when I
changed bands (I'm trying to keep costs down). Then I read N6BV's book, "All
the Right Angles" which gave me an idea:
Can you use a coaxial switch to change between stubs?
For the coaxial stubs that are not in use and are connected to the switch, do
they effect the SWR and impeadance of the antenna transmission line? I put a
few stubs on my 6 position grounding coaxial switch, and hooked it up to the
network analyzer. The shape of the rejection notches remained the same, though
the notch frequency was lowered by up to a couple hundred kHZ. I am not sure
if the lower resonant point is due to the grounded coax cable which is hanging
off the active stub, or due to the extra length found in the coaxial switch
itself. I tried removing one of the stubs and didn't notice any change in
resonant point so I suspect the lowered frequency is due to the switch. My gut
tells me that the grounded hanging coaxial stubs have to have some effect which
I haven't detected yet.
The one disadvantage I see is how to connect 2 stubs required for a particular
band, unless I insert another coaxial switch down line for the parallel stubs
required that particular band.
I suppose an altenative way would to use relays and remove the stubs completely
from the line/circuit, but that project will take a bit more work than just
hooking them up to a coax switch I had laying around!
Any thoughts on this situation? Many thanks for your help on previous
bandpass filter designs and HF packet issues! You have been a great source of
knowledge and assistance!
Regards,
Ken, WM2C
>From Skelton, Tom" <TSkelton@engineer.clemsonsc.NCR.COM Fri Sep 24 16:58:00
>1993
From: Skelton, Tom" <TSkelton@engineer.clemsonsc.NCR.COM (Skelton, Tom)
Subject: test
Message-ID: <2CA3199F@admin.ClemsonSC.NCR.COM>
This is a test. MY mail to DX Reflector is bouncing again, and I
want to make sure CQ Reflector mail isn't bouncing also. Sri
for b/w.
Tom WB4IUX
>From Skelton, Tom" <TSkelton@engineer.clemsonsc.NCR.COM Fri Sep 24 17:22:00
>1993
From: Skelton, Tom" <TSkelton@engineer.clemsonsc.NCR.COM (Skelton, Tom)
Subject: VK9MM on 80m...NOT!
Message-ID: <2CA31F56@admin.ClemsonSC.NCR.COM>
This morning, 24 September, we had some good conditions on
80 meters to the Pacific. The VK/ZL stations were 56-57 at
sunrise, and I worked V63JC on 80 SSB. VK9MM was on 80
for a few minutes, and then went to 160. Another VK9MM
station was on 40 with a big signal, went to fill the generator,
and then instead of coming back to 40 for east coast sunrise
they showed on 30 meters.
I told the op on 20 meters last night that their signal was not
what it should be on 80, particularly since they were so loud
on 40. I tactfully thanked them for the great job they were
doing, and suggested they check out their 80m antenna/coax/
etc. Another station on our local packetcluster asked them
to please be on 80 from 1100-1200 for east coast sunrise.
Both requests seemingly went unheeded.
They are doing a fantastic job of satisfying the demand on
40-10 meters, including 30/17/12, but I have to say I wish
they could focus more on 80.
The op on 20 last night also said that they would QRT the
night of September 28 on the island, and leave the morning
of September 29. So, we have 4 more days.
I am cross posting this to CQ Contest....please forgive me
Trey, but my mail to the DX Reflector is bouncing and I know
there are a lot of Contest readers also reading the DX
reflector.
Before anyone decides to flame me for being a whiner, I
can assure you if I had the money I would be the first on the
boat to go!
73, Tom WB4IUX (S. C.)
>From Walter Kornienko (GC-DSTI) <waltk@PICA.ARMY.MIL> Fri Sep 24 15:17:57 1993
From: Walter Kornienko (GC-DSTI) <waltk@PICA.ARMY.MIL> (Walter Kornienko
(GC-DSTI))
Subject: VK9MM on 80m...NOT!
Message-ID: <9309241017.aa25344@COR5.PICA.ARMY.MIL>
Their signal on 80M has been stupendous, considering where they are
and the circumstances they're operating under. With a 52' vertical
they have been very close to S-9 on more than one occassion. Copy on
the NW bvg is better, but only w/respect to Signal-to-Noise ratio.
They showed on 10M yesterday, 9/23 (abt 1800EDT). This was the shortest
band opening I've seen in 27 yrs of operating. If it wasn't for the darned
RF getting into the mike, I would have gotten them. But, alas, Murphy came to
visit this ham. Maybe next time... 73 de Walt - K2WK
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