On 9/8/2015 5:22 PM, Peter Voelpel wrote:
That shorted stub cut for 20m has to be installed on the 20m station
(station B) to suppress 40 and 15 there. On the 40m station (station
A)you will need an open stub cut for 20m to suppress 20 and 10m
interference. Both stubs will be around 23 feet long when made from
RG213,
What would you recommend if you had 2 el 40 on one tower
and tribander
on second tower. I have considered experimenting with
so2r but just 20 and 40
meters to see if I can handle it.
BoB WA1FCN
73 Peter -----Original Message----- From: CQ-Contest
[mailto:cq-contest-bounces@contesting.com] On Behalf Of Mike Smith
VE9AA Sent: Dienstag, 8. September 2015 23:14 To:
towertalk@contesting.com; cq-contest@contesting.com Subject: Re:
[CQ-Contest] Coax Stubs for SO2R Thanks for the many replies so far.
So today after I got home from work I tried just running radio A @
about 1w on 7.000MHZ and saw S9 on 20m and s1 on 10m. No change
switching stub in or out, so I took Jim's(K9YC) suggestion and moved
the stub farther away from the transceiver. I made up 3 random length
patch cables and so have the stub roughly either: 10-12', 15'-17,
20'-22, 25'-27 away from the transmitter (Radio A). (rough
guesstimates) ( a 1/4wl, accounting for VF would be in the 23'-27'
range) No perceptible change whatsoever at any point in the line no
matter where I put the stub. Just the slightest SWR change when I put
it in line. Almost cannot detect it. I am going nuts. It's either
something in the shack or something outside rectifying (I guess?) but
these are pretty low power levels. (usually 100w, but also at 1w !)
Radio A (transmitter in the scenario) is hooked to an amp (not turned
on in close to a year), an antenna switch, a tuner/wattmeter (used on
straightthrough function only, just for it's wattmeter/SWR function.)
Radio B (receiver in this scenario) is hooked to its own power supply
and coax straight outside to a multiband dipole some 100' from the
Radio's A's various antennas. No SWR meters, switches or anything.
They share a 4" hole in the wall in the garage where they exit to the
outside, where the RG8 or LMR400 coax;'s could be close to one
another. They share 120VAC in the shack (but different power supplies)
I have two additional (perhaps important?) questions. Should any of
these harmonics between any bands sound pure and "clean", like a real
CW signal? Mine all sound low/muffly, wide, growly, like they have
buzzing/humming AC riding on top of them. Additionally, the
AA-230pro's manual says to make the 1/4WL stub with the end of the
coax OPEN. . . . .but then for the purposes of these tests, I am using
the stubs shorted. Maybe I have a ground loop somewhere and there is
feedback or an isolation problem on the shacks's 120VAC line? Mike
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