Guy, Again your ability to write down what is REAL and what is NOT is again 'right on the money'.
This last post of yours should be REQUIRED reading by all new owners of the K3 to help them better understand the radio, the design and the capabilities. Maybe even a version of your explanation should be included in the K3 manual or at the very least be included in a 'TUTORIAL' available to all on the Elecraft website. Thankyou. Gary On 14 April 2011 02:08, Guy Olinger K2AV <olin...@bellsouth.net> wrote: > Yes, it certainly IS that simple. > > I remember the old radios well. They never had the "problem". They > didn't have enough gain to have the "problem". Nor was it possible to > have the AGC recover in such a short interval that the noise sounded > as if it were the same level as the desired signal, even if many S > units weaker. Using RC timing only and a single voltage bus, really > fast AGC produces really obvious distortion. > > So why have digital methodology that can produce setting combinations > that produce roar-in-your-ear behavior? Very simple. People wanted > the options and to be able to set it just like they wanted it, so the > available ranges of AGC constants were set to allow people to set it > to taste. If you go back and read the archives, people were pretty > sharp-tongued about having all the options. > > But whether consciously or not, many (most?) people were EXPECTING the > K3 to sound like Pappy's analog radio, and divergences were reported > as K3 "troubles", and still are. AND, as it has always been on the > old radios, once AGC was on the scene, the only setting used for RF > gain was wide open. > > And wide open is now 30 db farther down than Pappy's old analog radio, > AND can do all that without distortion. Someone was asked why he was > running RF gain at max and PRE on on 80 meters. He thought about it a > while and said he guessed because he always had. And sure enough, > looking at a now idled older Yakencom rig, that's how it was. Turned > it on and the older rig *NEEDED* the PRE on 75 meters for morning SSB. > And right beside that was an old Ameco preamp to put in front of the > radio's built-in preamp if you wanted to hear anything weak on 15 and > 10 meters. > > RF gain maxxed out is just habit and we are taking some time getting > used to stuff that doesn't act like the old radios. > > On my K3 on 80 and 160 I use the attenuator on and the preamp off when > listening to the transmit antenna. I have an on-the-ground loop array > listening antenna, and when listening to that have ATT off and PRE on. > The 20+ dB difference between ATT on and PRE on almost makes up for > the RX antenna's normal very low gain. If I flip the RX source with > the RX front panel button, the K3 seamlessly switches the ATT and PRE > in and out. Very nice, very handy. It also makes for stellar > diversity because the same trick is available for the second RX. > > That very useful convenience being in play for anyone who buys a K3, > means that everyone has to understand PRE needs to be OFF and ATT ON > for 80 and 160 listening on transmitting antennas, and adjust > accordingly. > > Fail to do that, and somebody has a K3 noise "problem". > > But the fix is between the ears, not in the K3. SETTINGS, which is > what we are really talking about, are the user's problem. > > I'm watching my incoming noise tonight on 160. S5 between strike QRN, > with that up to 20, 30 or 40 over. That's something like -100 dBm > steady. -100 dBm just tickles the S-meter on my MP. On the K3's > S-meter, where calibrated S units ACTUALLY ARE six dB per step, S0 > actually *IS* 54 dB below S9, which actually IS -73 dBm. So, watching > both of them, the K3 is five S units noisier than the MP, or that's > how it gets reported -- "my K3 is terribly noisy on 160 and 80". Add > to that the maxxed out RF gain, plus PRE turned on, plus unfortunate > user-chosen ACG settings and the user expecting it to act like old > analog radios, and not understanding the differences, we have one > unhappy owner. > > My MP's S meter is a liar. What was really going on was that the AGC > and the signal measurement ARE THE SAME CIRCUIT, as they have been in > all the old radios. The truth of the matter is that S0 (no > deflection) is 54 dB below 50 microvolts across 50 ohms or -73 dBm. > So S0 is -127 dBm. > > Our old radios had NO chance of AGC engaging at -127. A lot could not > even HEAR -127. So the S-unit scale was a lie TO BEGIN WITH. What > radio manufacturer is going to tell the truth and start his S-unit > scale at S5? Now you have explained the MP's compression of S-units > into 20 to 25 dB. And what manufacturer is going to take the AGC bus > and show how cramped the range is on top, and put S9 to 40 over in the > right 1/6th of the scale? So on the old radios you have a meter that > doesn't show you much more than one signal is louder than another. > > Calibrated K3 tells the truth. The firmware program analyzes multiple > states in the radio, and runs it through a calibration table to > compute the actual signal strength. Personally, I wish there was a > way to have the K3 (by itself) read out in dBm at the antenna. > > The K3 ain't your daddy's analog radio, however much we are > unconsciously looking for that. But once you learn and get used to > the new stuff, you'll never wanna go back. No way. > > 73, Guy. > > On Tue, Apr 12, 2011 at 6:45 PM, Barry N1EU <barry.n...@gmail.com> wrote: > > > > Bob,w5pvr wrote: > >> > >> The noise between transmissions was like Niagara Falls but not > >> any more. > >> > > Turn down the RF Gain. It really is that simple. > > > > 73, Barry N1EU > > > 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:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > -- *VK4FD - Motorhome Mobile Elecraft Equipment K3 #679, KPA-500 #018 Living the dream!!!* ______________________________________________________________ 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
