(K2 #6800, KAT2, KSB2, KIO2, KNB2) Hello all,
I know many electrons have been spilled on the reflector regarding this topic, however, I'm still not able to resolve my situation. Problem 1: When attempting to fine tune the AGC threshold, I can differentiate a volume difference between AGC On and AGC Off as expected. The problem is there isn't much difference in this sound delta when adjusting the AGC Threshold Voltage (U2, Pin 5) going from 3.8 V down to below 3.5 V. The voltage needs to be below 3.5 V for my ears to detect a “significant” change. My understanding is that AGC Threshold Voltage should not be set below 3.6 V. I'll be the first to admit my ears are not that sensitive, so I hooked up the K2 to Spectrogram to see if that would help me detect a significant change. At 3.8 V, AGC On versus AGC Off produced about a 3 dB delta. Adjusting down to 3.5 V, the delta increased to maybe 4 dB, but it's hard to tell. Between 3.8 V and 3.5 V it's really difficult to detect much difference at all. The Regulator Voltage on U4 Out is 8.05 V. I read on the reflector that this should equate to a AGC Threshold Voltage of roughly 3.78 V. At 3.78 V, there is virtually no difference between AGC On/Off. This may be all a moot point, because I simply set the threshold voltage at 3.7 V and seem to get decent S-meter deflection. However, I absolutely can not get the S-9 calibration with a XG1 signal generator (see Problem 2). Problem 2: Before attempting to calibrate for S-9, CAL S LO is at 185 and CAL S HI is at 017 (Preamp off) and I get a working s-meter. However, when setting CAL S HI with a XG1, the CAL S HI value is 002 (Preamp off). The meter is then always pegged at S9, even when there isn't an antenna plugged in. I've done this calibration several times, adjusting CAL S LO, then CAL S HI, with the same results. I'm starting to think there is something wrong with my XG1, even though I can hear the signal clearly at 7040 kHz. Any ideas would be much appreciated! The K2 is working great other than this issue! 73 Brian - N5BCN ----- K2 #6800 KSB2 KAT2 KIO2 KNB2 -- View this message in context: http://n2.nabble.com/K2-Difficulty-Fine-Adjusting-AGC-tp4019552p4019552.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ 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
