This has been really interesting. I hope you all are learning as much as I am. So, I really made some crude stubs from some old RG-8. A "T" on one end and a shorting switch on the other end. Both ele
Properly done, they can kill second harmonics of the power amp. That's a big deal when you're operating SO2R CW on 80, 40, and 20. What's the advantage compared to LPF or BPFs? Most of these filters
Well .. with this kind of arrangement, as you are not exactly optimizing the last deciBel out of your system, experimenting is the key word. Dual stubs are out of the question as you want to have tha
Here is a video of the stub, switching the end short. https://youtu.be/wgn_L_LUXcI Depending on the band it either passes or blocks. And quite a bit. They are identical, I off the top of my head do n
Your logic is exactly backwards, Jukka, and it applies ONLY to optimizing the relationship between the stub and the power amp. When the output circuit element is a capacitor, the stub should be 1/4 w
Excellent show what a simple stub can do. And, when passing the receiver signal, the stub does the same effect to the transmitted signal. It attenuates the signal on the unwanted band. Excellent show
Author: Rudy Bakalov via CQ-Contest <cq-contest@contesting.com>
Date: Mon, 18 Jul 2016 17:37:52 +0000 (UTC)
If we are learning that stubs cannot be placed randomly, is there a method of tuning a stub that is placed randomly along the feed line? For example, for an existing installation, there is the existi
I will try and answer each question below: 2016-07-18 20:37 GMT+03:00 Rudy Bakalov via CQ-Contest < cq-contest@contesting.com>: They can be placed randomly. Even if the stub is not exactly on the her
Umm .. I did not exactly finalize the email before sending. The missing content is here: There are two things to recognize when making RF filtering; in this case with stubs: Stub tuning Placement of
Author: Rudy Bakalov via CQ-Contest <cq-contest@contesting.com>
Date: Mon, 18 Jul 2016 15:17:56 -0400
Hi Jukka, Thanks for the detailed response. Your original email was clear...at least to me :-) I assumed from the very beginning that stub tuning and placement are two different steps. What I was won
Jim right of course -- the exception being the old Alphas with Pi-L outputs. At the the old K1AR M2 we ran from my house we used a lot of stubs because we only had two towers. Stubs made with hard li
Thanks Rudy .. In case you really split the hairs, there is a connection between the two; placement and length; but it is weak. In case you really want to experiment, make the stub a little long. -if
I posted the link twice. 73, Jim K9YC On Mon,7/18/2016 10:37 AM, Rudy Bakalov via CQ-Contest wrote: If we are learning that stubs cannot be placed randomly, is there a method of tuning a stub that is
There are many amps with Pi-L outputs. There's a table of those I've been able to learn about (with help from friends) at this link http://k9yc.com/Coax-Stubs.pdf At the the old K1AR M2 we ran from m
In case you really split the hairs, there is a connection between the two; placement and length; but it is weak. This is false. In case you really want to experiment, make the stub a little long. -if
In case a person wants to experiment, he can do some experimentation. My email was written so there is no complicated measuring equipment. That is, there is no need for antenna analyzers. You can us
Hello have anyone tried making stubs from RG11 coax? I determine i have some good lengths in stock and I have always used RG213 for stubs. 73s LB3RE Rag Den tir, juli 19, 2016, 00:10 skrev Jim Brown:
might be one tale to tell I will think about this from the perspective of how a person might do an experiment to demonstrate the concept. I've already added material on stub placement to both the An
OK, We all have here been discussing harmonics. While I have heard harmonics, and these stubs help greatly with that problem. I personally get more results from protection from ummm, wide band noise?
"*Yes, a very good move. But when we're talking stubs for harmonic suppression, we must measure that coupling at the frequency of the harmonic.*" Jim is correct. By measuring the coupling of 10 into