All tuners will eat up some percentage of your RF output power. The ones with toroid or smaller inductors may eat up more power. Just how much power depends on the reactance/impedance transformation required and the Quality of the components. You can see that a test using a 50-ohm wattmeter on the input and another on the output Is not a true indication of the tuners capabilities- though that is probably what Some manufacturers to for their "tests". The real test would be to measure a wide Number of resistive (and reactive) loads on a large number of frequencies.
One good start might be to measure RF voltage VPP across the resistive load after The tuner has been adjusted. VPP on a good oscilloscope is more accurate an RF Power measurement than most wattmeters- especially for QRP. Some correct if I am wrong but I believe the formula is Pwatts = 0.35355 x VPP scope reading Then square the results, Then divide the results by the load resistance 50- or the value that you chose for testing the tuner. Jay W6CJ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Harper AE5X Sent: Sunday, August 07, 2005 4:05 PM To: Elecraft Subject: [Elecraft] Re: Elecrafts T-1 Jerry, I built one right after they came out and in one fell swoop, it made all my monobanders much more easily portable. It has replaced my old workhorse, Emtech's ZM-2 and has partially replaced the MFJ tuner I use on my 100-watt rig (with power turned down to 25 watts or so). Easy band changes without the "look at the meters while rotating the knob" routine. Between home, field operation & Field Day 2005, I've used the T1 with all my rigs and a borrowed K2 on various combinations of the following antennas: ladder line-fed 40m dipole 80m G5RV 2 element 40m wire beam 30' wire + 1 radial 20m hamstick mobile whip (on 20 and 30m) The T1 has tuned them all to a ratio of 1.4:1 or less, usually less. Soon after building the tuner I would always go back and verify that the SWR really was low. I did this buy disconnecting the rig and attaching a Bird antenna analyzer. A few months ago, QST had a review of 5 or 6 kilowatt tuners. The main gist of the article was not whether or not the tuners would tune various antennas on the HF bands for which they were designed, but with what efficiency the mismatches could be transformed. This is my question on the T1 and every tuner I use. For 5 watts out of the transmitter, how much of that goes to the antenna when I use the T1 rather than the ZM-2, etc... That's what I want to know, but darned if I know how to make such measurements. John Harper AE5X Portable QRP: http://www.ae5x.com _______________________________________________ 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 _______________________________________________ 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
