Has anyone seen anything in print about using a lambda/4 (Quarter wavelength) stub on the output of an amplifier with a tube. Its a nice way to bring water, tuning mechanisms into an output circuit,
W2VJN's book have this ! 73 LA6FJA Rag _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
I will display some ignorance here: Does the plate current waveform distortion cause any problem at the fundamental frequency? Your idea for using a quarter wave stub like that is interesting. For a
Say what ??? Don WA4NPL _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
Those are fairly common for multi TX stations to knock down harmonics and phase noise. I use stubs on the feedlines of all the monoband yagis and typical rejection is 25+ dB using CATV RG-11. On 80M
Yes. I'm currently working on a Q&A style tutorial on coax and stubs. The first draft is at http://audiosystemsgroup.com/Coax-Stubs.pdf Comments are appreciated. I would especially appreciate additio
Jim Thanks for the tutorial. I've often wondered about the movement of energy in and around a stub. Harmonic energy is delivered from the PA to the output feeder and onwards to the stub. Would I be r
Get your calculator out. 30dB down from 1500 watts is how much power? 1500 watts=+61.8 dBm minus 30 db (which is what the harmonic would be down normally) = +30dBm. +30dBm = 1 watt. Evenif the harmon
That's why all this talk about HIGH POWER is kinda a non issue.... At least for me. Except for not being gentlemanly and legal. 1500 watts is +62 and 5000 watts is +66 ...Then the guys that reportedl
Don't think a calculator is needed. 30dB is a ratio of 1000 so that would be 1.5 watts. Jim, AF6O _______________________________________________ Amps mailing list Amps@contesting.com http://lists.co
Or would the "zero-ohm" load absorb most of the harmonic ? ( a case for a high-pass filter terminated into a dummy load ? ) Don WA4NPL _______________________________________________ Amps mailing lis
IMO, the best ones were written in the NCJ and individual club contest juournals by those who actually needed, developed, used and refined them. Stubs can be designed to work anywhere you want them.
Yes, the stub burns most of the harmonic power that hits it. While we talk about a "zero ohm load," it's really some fraction of an ohm depending on the loss in the coax used to make the stub, so the
When I first started using HF stubs in the early 80's I used a noise bridge and RG-58 figuring it would be fine and cheap. The null was rather broad and the stub heated up considerably as the frequen
ORIGINAL MESSAGE: REPLY: Don't need a calculator. Each -10 dB = 10x power reduction. 10 dB down from 1500 watts is 150 watts. 10 dB down from 150 watts is 15 watts. 10 dB down from 15 watts is 1.5 wa
Thanks for doing the sums, Jim, I was interested in the theory. I thought energy would be reflected in both cases of open and closed circuit stubs. Something new to learn every day. David G3UNA Get y
Author: "Dr. David Kirkby" <david.kirkby@onetel.net>
Date: Sun, 04 Apr 2010 00:11:18 +0100
I don't know how you arrive at 1 W, but just by looking at it one should be immediately possible to see it will be 1.5 W. No need for a calculator. dave ______________________________________________