Thank you John! You said it in terms that I wasn't dealing with at the time. I was still working on my first cup of coffee, and being pestered by a 13 1/2 year old ShiTzu, that wanted a snack and another run outside to take care of business. <sigh>
Makes it hard to keep the thought train running in the right direction. The effects of link coupling are significant. You've pointed it out VERY well! I haven't used a swinging link since building a 4-1000 amp with the info from Eimac. Mostly I deal with rotating links. Bob - N0DGN John Coleman wrote: > Brian: > In a link coupled assembly the coupling actually has an effect on the > Q, the effective load. But increasing the Q of a parallel tank (less coil > more capacitance) will increase the coupling. Using taps on the coil for the > antenna connections reduces the coupling while increasing the Q. The fewer > turns there are between the antenna connections the greater the Q of the tank > but less voltage is coupled to the antenna. The coupling between the link > and the main tank increases because the Q of the main tank went up as it was > loaded less. The voltage across the ends of the main tank will go up as the > taps are moved towards the center. You can get a different run of coupling > by tuning the link in parallel instead of series. But this will double the > voltage across the link capacitor. You can get yet another run of different > coupling factors by using a swinging link. > It all boils down to this: The tuner should be adjusted so that there > is no L or C reactance at the antenna terminals. Then the coupling is > adjusted to pull the current from the rig so that Erf/Irf = desired Z-load > (generally 50 ohms). > If the Q of the circuit is not high enough you will not be able to > couple enough energy out of the XMTR to draw enough RF current to get the > desire E/I (LOAD resistance) low enough. > If the Q is too high in the wrong place then the circulating currents > in the tanks of the tuner will either have high loss or begin arcing. If it > aint getin hot and it aint arcin then it's OK. > There always a number of ways to do it. > > BTW: I was in your neck of the woods a couple of weeks ago visiting with > Kids in Searcy and drove out to the Peti-Jean park. I guess we must have > gone right by you place. > 73 > John, WA5BXO > ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
