On Thu, 15 Jan 2009 09:15:36 -0800 (PST), you wrote: [snip]
Comments in line... >I have it connected through a tuner and then to the SB-200 and then Dipole > >K3/100/ATU <-> MFJ tuner <-> SB200 <-> Dipole > >If I use Auto mode on the KAT3, put the MFJ tuner in Bypass and hold TUNE >then the KAT3 goes and brings the SWR (according to the display) to a >favorable value (1.0 to 1.2). I use a MFJ tuner between my Rig and Amp >because the Old Bard told me to. Actually my setup is different than >what I just described, but I'm simplifying this for the question at hand. > >[ What I really do is K3 <-> Small MFJ Tuner <-> SB200 <-> Big MFJ Tuner ><-> Dipole ] I don't know why the "Old Bard" told you to do that. It makes no sense to me. First of all take the small MFJ tuner out of the line and connect the K3 directly to the SB200. The tuner in the K3 will do the job of the small MFJ tuner. No sense adding tuner loss between the Amp and the rig. I suspect the "Old Bard" told you that because the input of the SB200 is not 50 ohms. More about that later... >On the watt meter of the (small) MFJ Tuner, the indication is I have a non >favorable SWR, more reflected power than had I put the KAT3 in bypass and >manually tuned the MFJ Tuner to a favorable SWR (1.0 to 1.2 or so). This indicates that the SB200 input is not 50 ohms. You may have some troubles with the SB200 input, but you should be able to adjust that. Look at the SB200 manual and see if it has input matching adjustments. You certainly don't need two tuners for the SB200 input! > >So, can someone explain in basic terms what's happening when I use Auto >mode on the KAT3 and see favorable SWR on the KAT3 (via K3 display) but do >not see favorable SWR on the MFJ tuner? Here's what is going on. In the configuration you have now, you are correcting the mismatch between the small tuner and the K3. When you remove the small tuner you will be seeing the input of the large tuner (If you have the amp turned off or in standby.) When you use a tuner on an antenna, you don't change the antenna, you change what the rig sees at the feed end of the coax. I have an amplifier and large tuner. Here is what I do when using an antenna that doesn't have a good match. 1. Put the K3 in tune (hold the XMIT button). Adjust the large tuner connected to the output of the Amplifier for the lowest SWR. You want the amp turned off or in standby at this point. 2. Turn off the tune on the K3. 3. Make sure the power setting on the K3 is set below the normal drive power of the Amp. 4. Turn the amp on or take it out of standby. Hold the XMIT button in on the K3 and adjust the amplifier's tune and load according to the manual that came with it. Your K3 tune level should be about 15 or 20 watts or something below the full output drive of the amp. Turn off the K3 tune. 5. If, and only if you saw a high SWR on the K3 meter, tap the ATU Tune button and tune the K3 to the input of the amp. 6. Hold your CW key or what ever your using to send input power to the amp and adjust the amp tune and load for the output you want from it. Now you're good to go :o) 73, Tom, N5GE http://www.n5ge.com http://www.swotrc.net [snip] _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
