Jack, Thanks for the detailed explanation. So, if the K3 pulls the keyline to ground and the STBY/OPER switch is inoperative as a result, then why would power cycle on KPA500 change things. I mean, I assume that the keyline is still pulled to ground by the K3. But, I admit that I am not an electronics guy as you others so I do not fully understand all of the stuff that goes on in these things.
73, phil, K7PEH On Apr 22, 2014, at 10:18 PM, Jack Brindle <[email protected]> wrote: > There appears to be some misconceptions in this discussion. First, the > information flow from the K3 to the KPA only occurs on the band lines and the > key line. Auxbus communications is one-way, from the KPA to the K3. The KPA > does not listen on the Auxbus. > > There is also something else going on that is in play here. When the K3 is > powered off, the pull-ups on the band lines (and the key line, I believe) > continue to work. They continue to pull the lines to Vcc. But with the K3 > off, Vcc is now 0 volts. This means that a short time after the K3 powers off > the KPA will see all zeros on the band lines, and will switch to 60 meters. > After this, RF coming into the KPA will cause it to switch to the appropriate > band, and all band switching will occur with incoming RF as long as the band > lines do not change. > > Of course, there is one other signal in play here. The Key line is important > since it causes the KPA to switch into transmit. We have seen the K3 pull the > Key line to ground at times, which just may be what you are seeing. If the > KEY line is active, the KPA will not switch from STBY to OPER. For this to > happen the KEY line must be high. > > The best way to connect two transceivers to the KPA is to use a physical > switch to select the transceiver. A five-pole two position switch will do for > the band and key lines, plus a coax switch of the RF. > > In short, you may get things to work with the description from Fred’s book. > But if the key line becomes driven low by the “off” transceiver for any > reason, you can expect weird things to happen. > > Jack Brindle, W6FB > Elecraft Engineering > > On Apr 22, 2014, at 5:04 PM, Phil Hystad <[email protected]> wrote: > >> Don, >> >> OK, I may be expecting too much. Actually, I am not sure if I was expecting >> as much as I was a little bit surprised by the behavior. I didn't think >> that the KPA500 and KX3 communicated with each other other than RF and Key >> line but maybe that was enough of a difference from the K3. The K3 of >> course in my case has the AUX cable connections with the KPA500 and KAT500. >> >> It is not a big deal as long as this is the way it is expected to work. I >> was not sure if I had done something wrong or not. >> >> But, just picked up W1AW/5 MS QRP power with the KX3. Actually, it was >> about 6 watts. >> >> 73, phil, K7PEH >> >> >> On Apr 22, 2014, at 4:57 PM, Don Wilhelm <[email protected]> wrote: >> >>> Phil, >>> >>> I think you may be expecting too much. >>> Consider a parallel - a computer communicating with a printer. If you >>> suddenly switch the printer cable to another computer, would you expect the >>> printer to continue printing without any intervention? >>> >>> The "printer" in this comparison is the KPA500 and the two "computers" are >>> the K3 and the KX3. >>> >>> It is not unreasonable IMHO to expect that a reset of the KPA500 would be >>> required. >>> >>> If the KPA500 were simply an amplifier with no communications capability >>> with the driving transceiver, switching from one source of RF input to >>> another should proceed without regard to whatever is the driving device, >>> but your KPA500 is more than "just an amplifier" because it can communicate >>> with the K3 or KX3 driving transceiver. Expecting the KPA500 to switch data >>> streams from two different transceivers with no intervening reset is not >>> realistic. >>> >>> 73, >>> Don W3FPR >>> >>> On 4/22/2014 7:41 PM, Phil Hystad wrote: >>>> So, is this normal behavior? I wasn't expecting any kind of comms between >>>> the K3 and the KPA500 that affects the STBY/OPER switching. It does seem >>>> that a power on/off cycle for the KPA500 is required to enable that switch. >>>> >>>> Is this designed to work this way or is this a flaw in the design or maybe >>>> a missing mini-feature of configuring two different transceivers with the >>>> KPA500. I admit to not scouring all of the documentation yet on the >>>> expected functionality of the STBY/OPER switch. >>>> >>>> 73, phil, K7PEH >>>> >>>> >>>> On Apr 22, 2014, at 4:14 PM, Don Wilhelm <[email protected]> wrote: >>>> >>>>> Phil, >>>>> >>>>> Let me get this straight - the KPA500 is communicating with the K3, then >>>>> you switch to the KX3 and the KPA500 does not talk with the KX3. >>>>> >>>>> If that is what is happening, I would expect that to be the case. The >>>>> communications with the K3 is not synchronized with the attempted >>>>> communications with the KX3, so a reset (power cycle) of the KPA500 may >>>>> be required. >>>>> >>>>> 73, >>>>> Don W3FPR >>>>> >>>>> On 4/22/2014 7:02 PM, Phil Hystad wrote: >>>>>> Some follow-up questions: >>>>>> >>>>>> OK, I have the KX3 and K3 configured with the KPA500 and KAT500. >>>>>> Everything seems to work with one little exception. >>>>>> >>>>>> The exception: >>>>>> >>>>>> --- initial conditions, K3 is on and switched to use the KPA500 and >>>>>> KAT500. KX3 is off. >>>>>> >>>>>> --- using K3 and so on works fine with amp on or with amp in standby. >>>>>> >>>>>> --- I turn off K3. Leave KPA500 on but in STBY mode. >>>>>> >>>>>> --- Switch coax from K3 to KX3 (1x2 switch). >>>>>> >>>>>> --- Turn on KX3. KPA500 still in STBY mode. >>>>>> >>>>>> --- Attempt to switch KPA500 to OPER from STBY but switch does not >>>>>> work. If I power off the >>>>>> KPA500 (front panel switch) and power back on then switch works >>>>>> fine. >>>>>> >>>>>> I have experimented with all kinds of starting initial conditions and >>>>>> order of events but whenever >>>>>> the KPA500 is left on after using the K3 and then switching to the KX3, >>>>>> the switch on the KPA500 >>>>>> to go from STBY to OPER does not work. I always have to cycle the power >>>>>> from the front panel on/off >>>>>> switch. >>>>>> >>>>>> >>>> ______________________________________________________________ >>>> 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 >>>> Message delivered to [email protected] >>>> >>> >> >> ______________________________________________________________ >> 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 >> Message delivered to [email protected] > ______________________________________________________________ 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 Message delivered to [email protected]
