Don: I am officially stumped. I cannot find the fault in my transmit circuit but that is basically do to my inability to accurately measure ANY RF voltage. The RF probe doesn't seem to function. I have replaced the resistor and resoldered all the connections twice now but I continue to read betwen 50 and 70 mV with any handheld DMM and basically nothing with an HP3478A, I am using the DC volt setting. And all that 50 to 70 mV is across the 4.7Mohm resistor on the probe board. This reading masks almost anything I am trying to measure and without that capability, I am at a loss trying to trouble shoot the transceiver. Connecting the ground lead to the probe still leaves me with the same reading.
Is there any other instrument that I can buy or borrow that will accurately measure small RF voltages? Can I buy a working RF probe from Elecraft? Are there only certain DMMs that it will work with? Again, the receiver section and the panel and control functions work just fine but I only get about 0.5 mW on the readout with keydown. Brian Denley http://home.comcast.net/~b.denley/index.html > Brian, >Yes, I am sure about the 4.7 Megohms, but your 4.6 meg resistor will do >just as well. >It is DC voltage through the resistor, and it scales the peak RF voltage >down to approximate RMS. >Look at the schematic for the RF Probe on page 9 of Appendix E in the K2 >manual. >With the RF Probe, you will be able to measure RF voltages down into the >millivolt region. >Go through the steps listed in Appendix E of the manual under Transmit >Signal Tracing. >When you get to the points to measure on page 14 (assuming you do not >find a problem with the VFO or BFO), the RF voltages will be HIGHER than >the expected value because you do not have enough transmit output. What >you are looking for is the first point where the RF voltage is LOWER >than the expected value. That point is just beyond the failing stage, >and you will know which stage to examine in detail. >Only after your K2 is operating properly for RF output will you see the >expected values - go with the higher or lower criteria. >Don ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
