> Ed .... > > If I understand what I think you said, the agc settings are > dependant on: > Pre-amp on/off and / or Attenuator on/off > The DSP filter width > Which 1st IF filter is active
What I intended to convey was that to prevent overload, one should first make sure the front-end gain is not too high before worrying about AGC settings. Independent of AGC, the RX front-end can be too hot if the PREamp is enabled, e.g., on 40 - 160 especially, or if the ATTentuator is off on the low bands when signals are pounding in. My point about RX overload was to first turn off the PREamp and add the ATTenuator if required. The second point is to use the crystal filters as roofing filters to protect the DSP as the K3 was designed. The tighter they are around the DSP WIDTH you are using, the better protected the DSP is from nearby strong signal IMD. THEN, worry about setting the AGC parameters to optimize to your preference. It is futile to deal with RX overload with only the AGC if you've got the front-end too hot and have wide roofing filters letting IMD be created in your passband. > and ..... > the AGC SLP and THR settings are, for the most part a well > kept secret and not to be shared. Few people change the AGC settings from the default and even fewer people understand what the AGC settings do and how to adjust them to achieve what you want. This reflector has had some good posts on AGC parameters from W8JI and K8ZOA. So, I don't think AGC settings are secret and not to be shared so much as they are not well understood by many of us. Moreover, there is no single set of magic or ideal AGC settings for everyone and everyone's operating variations. The K3 defaults are probably the best single set of parameters for all of us. They may not be optimum in all situations, but they won't be terribly wrong either. > However mine are SLP= 8 and THR= 4 and, to me, it sounds > pretty close to the K2. I don't use NR much on CW because of > what it appears to do to the received CW signals. > This is with MCU 2.34 and DSP 1.81, which may affect how > those two settings are set. I'm using the defaults of SLP=010, THR=005, HLD=000, AGC-F=120 for CW. I used 2.38 and 1.90 in the CW Sprint last night. Wayne updated 2.38 fifteen minutes before the Sprint to fix a minor issue with how RIT Clear was working from our contest loggers. Both my K3s and at least two others updated with this firmware and ran flawlessly. (Those of you who worry about Beta releases posted on the Elecraft web site, take note. For 15 months now, I have always updated to the latest K3 firmware, even this close to the start of a contest. I would never do that with any other software or firmware. The K3 firmware updates are not perfect, but I have high confidence in them.) > If SLP= 8 and THR= 4 are bad settings, please tell me why. I don't think those are bad settings, but I haven't operated your K3 at your location at the times you operate, etc., etc. The whole range of possible AGC settings is reasonable depending on operating conditions and personal preference. Personally, the default AGC settings have worked well for me, so I haven't invested the time to experiment. Changing AGC settings is not something you can do and immediately know if they are "better". This is because every signal and band and noise situation is different, so you need to experience the AGC settings over a range of operating conditions. You may want to change one, or at most two, parameters at a time and operate with them for a while to anecdotally compare to the previous settings. Over time you can get a feel for how much change in each will effect your receiving performance in various conditions. I suppose one could put SLP and THR on Programmable Function keys and adjust them real time on signals, but I've not found that to be a priority compared to other things I need to be worrying about while operating. If I need to reduce gain quickly, I reach for the RF GAIN knob. If I feel the AGC is getting in my way, I may even turn it off and just ride the RF GAIN control. Most of the K3s at VP6DX were operated with the AGC off, so AGC parameter values were irrelevant in their rather challenging conditions. Still, I'm looking forward to playing with the AGC parameters some more and trying to optimize them for my various operating scenarios, but it is not a high priority need right now. To summarize, RX overload should be first dealt with by using the PREamp and ATTenuator to achieve the right amount of gain in the front-end. Once that is set properly, then you can use the RF GAIN control and/or the AGC parameters to fine tune performance. You mentioned NR. I haven't found NR to be useful at all for CW, and while it works well on SSB, I don't use it there either, preferring to let my brain deal with the noise. 73, Ed - W0YK _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
