Hello again, After my morning post, I decided to test the SDR system I am using to copy the 1296 beacon to see how it performs. Here are the results and here is the text I posted to the Softrock group: "I am testing my VHF Ensemble II, built for 144 MHz. I recently downloaded the latest HDSDR program and found the S meter calibration option. I have a very good signal generator with calibrated output from -143 dBm to +13 dBm from 10 Khz to 2 Ghz. I have verified the accuracy with my HP power meter. In other words, I trust what it says it is doing. I’m not trying to document the last .01 dB of the system, but I am mostly interest in the minimum and maximum detectable signal levels and the accuracy of the scale between them. I am using an external sound interface called “Ultimate USB Audio 2.0”. My computer (which really shouldn’t make a difference) is a Mac Mini running Windows 7/64 and the HDSDR program (of course). Here are my results. I can detect signals from -130 dBm to -20 dBm. At the high level the SDR saturates and the scale no longer tracks the input levels properly. The ten dB steps are right on the money all the way up from the minimum until it hits saturation at -20 dBM.” My next step is to see how the adjustments on the sound interface affect the system operation. I’m not quite sure how to proceed. I have asked the other group for advice on how to do it. Like this and other groups I belong to, there are some very good technical minds and they will set me straight, if necessary. 73, Dave, K4TO