Thanks Al. Well, the Figure 1 shows what I expected. Below the AGC gain threshold the output audio is the same with AGC on and off. Figure 2 is not expected, at least for me. Reducing the RF gain ought to reduce the audio levels, which you point out, and which it does. But, it reduces the AGC off signals more than the AGC on as shown in Figure 2. I made these measurements in the context of wondering why I find it necessary and and an improvement to turn AGC off when there is a pileup of signals all of about the same signal strength, something that has happened frequently for me when operating from C6. During our last operation, it was a real pain to switch AGC off and then have to turn up audio gain to compensate. It just seems strange to me that when AGC is on and we are below the AGC threshold, that the RF-audio level audio transfer characteristic is different than when AGC is off. 73 and happy holidays all, Fred KE7X
-----Original Message----- From: [email protected] on behalf of Al Lorona Sent: Wed 12/21/2011 10:46 AM To: [email protected] Subject: Re: [Elecraft] K3 RF Gain control reduced range after RFgaincalibration Fred, are you expecting the AGC OFF curves to always produce higher output than the ON curves? I'm not sure that's a correct assumption. I think the purpose of OFF is that you have control over the curve, that is, where you place the linear part of the dynamic range. It's like a variable attenuator in a spectrum analyzer. There are two truths regarding AGC OFF: As you reduce the RF Gain you should see a drop in audio output. AGC ON is always going to give you a more compressed input-output characteristic, compared to AGC OFF. That's what AGC does; it wants to make signals equal to a greater or lesser extent depending on your AGC parameters. It looks like your measurements have proven these two truths. A sudden 10 dB jump at the 9 o'clock or any position is an issue. This brings up a good point... all those who have been experiencing 'pileup mush' should make sure that their RF calibration is correct. I bet you that's half of the problem. Al W6LX ________________________________ There does seem to be something strange in the way the RF gain works. I also see the 10 dB change in audio level at the 9 o'clock position. In addition, the RF gain position seems to affect the way the AGC on and off works as shown on http://www.ke7x.com/home/miscellaneous-k3-information/unexpected-agc-behavior ______________________________________________________________ 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 ______________________________________________________________ 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
