Hello
Have anyone tried RG11 75ohm or cheap RG6 CATV cable for stubs???
Need something for our scout club JOTA LA6JAM
73 LB3RE Rag
onsdag, 27 juli 2016, 00:17a.m. +02:00 from Steve NR4M steve@nr4m.com :
>Jim,
>
>Been following this thread since it started (this time) several days
>ago. I have lots of interest in it as I have a multi multi station here
>in VA.
>I have built coaxial stubs in the past using my AIM 4170, FSJ4 heliax,
>and K2TR's data as a good place to start. I think after screwing with
>them for years, I've gotten pretty good at putting the nulls where I
>want them. And, they seem to work, but no real data on how well they
>work. My 40m 3rd harmonic on 15 is about S-5 and I can get withing a
>couple of KC, or so. It's just not much of a problem any longer.
>
>Been quite interested in your suggestions on how to place them for
>maximum attenuation of the undesired RF. I, like many, I guess, have
>installed them at the output of the amplifier, because that would be a
>50 ohm point in a properly tuned amp. But, now I see that it's more
>important to know what the impedance of the harmonics is on your band of
>choice.
>
>What got me up and moving on this is your comment in a previous post
>today about it being the second harmonic that's important. I have been
>building stubs, per N2TR, that covered multiple bands, without really
>focusing on a particular stations 2nd harmonic.
>
>I pulled the coax off the stub set on the back of my 20 meter amp,
>connected a Rig Exper AA54, and started looking up my coax toward the
>antenna.
>On 10 meters, I saw R101 -J14.6 and on 15 (for the heck of it) I saw
>R112 j-36.
>
>Following your instructions in your pdf on locating the stubs, I am just
>about where I need to be. If I added .44 feet of Coax, it would be
>right on the voltage peak.
>
>Do these numbers above look as they should? I was expecting higher R.
>--
>
>73 de Steve, NR4M
>
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