Stub QTHs - pretty much so a consensus...but

[BK1ZX70SFL at aol.com]

The question posed to the reflector audience: 

Where along the line should I put a stub whose mission is to subdue 40 meters
effect on our 15 meter station. This is the biggest intra/inter station
problem we have @ W1CW...minimizing the forty meter detrimental effects on 15
is something I wanna do....40 is our best band and I don't want to get to 40
too late just because we didn't wanna tear up 15. (Hint: the 15 meter
operator has a fit when the bloody 40 meter station QRMs him)

Mike, and all those who added their two cents - first off thank you. The W0UN
summary from the reflector sometime back was a great starting place for stub
enlightenment...it is on the KM9P Contest Reflector Web Page. Most of those
who  responded seemed to be thinking in terms of even harmonics, i.e. 40
messes up 20. A large number of you responded and it was great reading, but
the best response I got was from AD4VH who modeled a design using some
software....it is his design I will eventually try. 

I am a bit biased, you see Mike has been one of the operators at W1CW and I
like the idea of a fellow Florida Contest Group  member's ideas being
incorporated into the station....by the way Mike will you join us for the CQ
WPX CW - we will be masquerading as WC4E again, what say? I promise NO 160
meter duty this time :-)....we probably will hardly even be on
eighty...much...honest....hissssss!
 
I am just now getting to really reading all y'alls mail regarding the stubz,
and where to put them. The consensus as to where to put a stub as far as a
distance from the xmitter was 1/4 wavelength away. 

Mike, AD4VH's solution - courtesy of Superstar RF Circuit Simulator Software
(the name alone sold me), was to use two stubs....I gather that the first
stub recommended should be placed a 1/4 wave away from the xmitter, then
there should be just a lil bit more than a 1/4 wave spacing before another
equal length stub, then onto the antenna....both the stubs being open.

My question, I guess, is that I gather I  should get all the layout in place
and cut to tune the total of the cables that lead up to the first stub so
that the whole shebang totals 1/4 wavelength....yes? 

The station that is on 40 is also on 10 and there is a coax switch to pick
which antenna the output of the linear goes to....should I merely put the
coax switch in the line and create a 1/4 wave that includes the jumper from
the amp to the wattmeter, the jumper from the wattmeter to the coax switch
common, and then a magic length of coax which will make this whole sentence
worth of stuff look like a 1/4 wave? I think this is what several of you
hinted at. Okay next problem.

1/4 wave may or may not be long enough to get me out of the shack to the
outside wall of the house where I would like to hang the stubs...coiled up
neatly - placed on garden hose keepers....doesn't this sound nice and
orderly? If 1/4 wave isn't going to get me out of the shack, do I go to 1 1/4
(one and a quarter) wavelengths or should I go to 3/4 wavelength to get the
repeat of the sweet spot for maximum attenuation?

I am hoping to play with this before WPX CW...that may be tough
though.....W1CW just received a nice new Loos gauge and I wanna play with
that, too....and lets see this weekend is a computer show, then there's
moving a friend into his new apartment on the 27th, and the the weekend of
May 18 will be shot.....think I will be out of town for something. So the May
11 weekend, before that will have to be the station set up weekend....guess
I'd better get going....

Thanks to everyone for their input...but should I go 3/4 or 1 es 1/4 w/l???

73,

Jim K1ZX     
k1zx at contesting.com (<---vanity mailbox, getting ready for gate two)


>From Dean Norris <dnorris at k7no.com>  Thu Apr 18 03:20:46 1996
From: Dean Norris <dnorris at k7no.com> (Dean Norris)
Date: Wed, 17 Apr 1996 19:20:46 -0700
Subject: Beginner stn
Message-ID: <199604180225.CAA09064 at ssi.syspac.com>

I'm not a 'big gun' contester but do enjoy getting in once in a while.

My original call was KN0DON (January 1956) and my father got me a S38D and
converted Command Set/ARC 5 operating XTAL control on 7180 kHz.  These 2
delightful pieces of boat anchor were bought at Burghardt Radio
Supply/Molstads in Sioux City, Ia.    He became terminally ill shortly
before I actually got my ticket and was never able to see the station or me
operating.  Anyway, it didn't take long to realize that the S38D was a dog
and I got an S-85.  WOW.  A 40 meter _folded_ dipole suspended from 2 trees
with 300 feed line to a pair of 4:1 balun coils and a knife switch antenna
change over.  The PS for the ARC 5 was 2-816 rectifiers EXPOSED on a steel
chassis and to switch over the antenna, I had to reach over the plate caps.
When I didn't get nailed by the plates, I got stung by the RF on the balun
coil.  Little white spots that hurt like hell.  I learned to swear at the
age of 14! 

I didn't have any metering and always thought it was running about 50-75
watts.  Later I found out that the ARC 5 was actually putting out less than
10 watts.  NOT close to being tuned properly!

Later, in '57 I got a Viking Ranger (tears...what a rig).  My first contest
was SS in 1956.  I was hooked.  Still try to get in a few each year.  

I would like to take the opportunity to honor the memory of 2 nice hams that
helped me a whole lot in those days.  W0DSP, Andy Woolfries, and K0AVW, Don
Murkins.  Both have passed on but my thoughts are with them.  Good DX fellers!

cdn

           C. Dean Norris
      Amateur Radio Station K7NO             
      e-mail to dnorris at k7no.com