It is a common misconception that Bird Thrulines are a always accurate. They are good when operated into a matched load and when the signal does not have a high harmonic content. If there is reflected power you need to make a correction. If there are harmonics, even if at a low level, the sensor can read much higher power than is actually present, even into a well matched load. Bird Slugs can become damaged, mechanically or electrically and I have even come across ones with the wrong label.
So, I dispute any claim of accuracy of a power meter just because it is a good make. All power meters can on occasion give incorrect readings. The Bird 43 claims 5% of FSD accuracy. On a 250W slug an error of 12W. 180W could, within the meter specification be 170W. Then the 250H slug also has a frequency response. To the problem in hand: The low pass filtering in the K3 should prevent any over-reading being the harmonics, unless there is a problem in the filters and assuming there is not a mis-match, we have to assume this power is real. Specs indicate approx 18A at 13.8V, which is 250W input for 100W output. To get 170W or even 180W output is possible, but I think the PA is unlikely to be linear or long lived if used in this state. If the K3ALC is not working the PA may well develop this much power. I would re-visit the power calibration using the K3 utility. If that fails there is probably a fault. A linear amplifier designed for SSB will normally be capable of much more power than it's linear specification. Quite possibly double on the lower bands where the efficiency may be higher. While the amplifier can produce that power, the device may not survive the extra thermal stress. Mike -- View this message in context: http://n2.nabble.com/Re%3A-WHY-HIGH-RF-OUTPUT----tp2278215p2288751.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
