> So, the S-Meter calibration instructions in the manual indicate that > PRE should be on. When calibration is done, that means that a 50uV > signal reads S-9 with PRE on .. but about S-7 with PRE off. And then > if the mode is changed from Normal to Absolute, a 50uV signal reads > S-7 with or without the preamp.
Yes. In the end, you must calibrate the S Meter for how you use it. I operate in ABS mode, so I have PRE OFF and ATT OFF when I do the S Meter cal using a -73 dBm (50 uV) source. I could leave PRE ON in thie mode, but I know that the DSP is adding an offset when I do that (as it does for ATT), so I calibrate with both OFF. If I then go to the "other" S Meter mode, it is inaccurate, of course. > Just wondering (maybe I need to RTFM and specs again), why that would > be the case, vs. 50uV being S-9 without the preamp. I have always > just ignored the instruction manual, and calibrated to S-9 with the > preamp off. So a 50uV signal reads S-9 (with or without preamp > engaged if the mode is Absolute). Correct. *** When you do the RF Gain Calibration procedure, it is important to know that your signal source is -73 dBm (50 uV). If you use the S Meter to make this determination, you need to know how it was calibrated. 73, Lyle KK7P ______________________________________________________________ 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
