There have been several concerns expressed on the reflector about how much power is being sent into the K3 RX antenna (also applies to the K2 with a K160RX option).
Rather than guess if that level is safe for the radio, why not just measure it? It is easy to do. Try this: Do you have a wattmeter that is accurate at the 1 to 2 watt level? If so, connect it to the receive antenna (make certain the antenna is terminated into a 50 ohm load either within the wattmeter or with an in-line wattmeter, connect the dummy load to the ANT side) - note that for this measurement, the receive antenna is the "transmitter". If you do not have an accurate QRP wattmeter, then connect the antenna to a dummy load and measure the RF voltage across the dummy load with an oscilloscope or an RF Probe. With an RMS reading RF Probe and a 50 ohm dummy load, 7.07 volts is 1 watt and 10 volts is 2 watts - with an oscilloscope (use a 10X probe), the peak to peak voltage would be 28 volts for a 2 watt signal and 20 volts for a 1 watt signal. If your dummy load is fully enclosed, you can gain access to the center conductor with a UHF TEE adapter. The K3 generates a HI RFI message in the VFO B display if the level is about 1 or 2 watts, so we can likely guess that level will cause no harm, and it should be below the level where the COR activates. If you have more than 2 watts from the receive antenna (from any transmitter running at its highest power and using any TX antenna) into a 50 ohm load, then I would recommend some secondary protection. If the level with your highest transmit power is less than 1 watt, then I would not worry about it. 73, Don W3FPR ______________________________________________________________ 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
