[CQ-Contest] Coax Stubs for SO2R

[Jeff AC0C]

That's a great way to start.  Especially as the solar cycle fades and 10/15 
are not open.  Then in the day, you run 40/20, and in the night you run 
80/40.

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-----Original Message----- 
From: rob
Sent: Friday, October 02, 2015 1:21 PM
To: cq-contest at contesting.com
Subject: Re: [CQ-Contest] Coax Stubs for SO2R

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 at contesting.com] On Behalf Of Mike Smith VE9AA 
> Sent: Dienstag, 8. September 2015 23:14 To: towertalk at contesting.com; 
> cq-contest at 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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