Re: [Elecraft] KPA100 Temp/Fan
Andrew Moore wrote: into RX mode -- it took a deliberate keying event to, apparently, force the firmware to re-evaluate the temp and disable the fan (which of course causes a transmission and confuses the op on the other I suspect this is because the AuxBus and peripheral microcontrollers are shut down in receive mode to prevent the pickup of digital noise. -- David Woolley Emails are not formal business letters, whatever businesses may want. RFC1855 says there should be an address here, but, in a world of spam, that is no longer good advice, as archive address hiding may not work. ___ 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
Re: [Elecraft] KPA100 Temp/Fan
When operating CW the fan turns on high during every transmission and the heat sink gets hot to the touch. I'm a ragchewer so my transmissions do run to several minutes and, regardless of power setting, the fan will kick on high after several minutes of transmitting. ... Does anyone have an idea what may be wrong? I think this is normal. I had the same experience and asked about it and in the end realized that's how it behaves. It's the primary reason I went back to the QRP cover. Fan is just too noisy and comes on too often. It also failed to turn off by itself after going back into RX mode -- it took a deliberate keying event to, apparently, force the firmware to re-evaluate the temp and disable the fan (which of course causes a transmission and confuses the op on the other end!). Where or not that part was normal I don't know, but it's the way mine behaved (on two different KPA100's). I don't know which firmware it had so don't know if that's been addressed in a newer version. If I remember correctly, the amp is most efficient at about 75 watts, so operating there might help cut down the heat and delay the fan turn-on. You might also look into other cooling methods -- larger, slower fan; remote fan with custom duct work; active cooling; etc. --Andrew, NV1B ___ 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
Re: [Elecraft] KPA100 Temp/Fan
Jim, The fan does go on and off by sensing the temperature of the heat sink (Q3 is the sensing element). The temperature that the fan transition occurs is fixed, but will operate at that fixed temperature only if CAL TPA is set correctly. CAL TPA must be set to the actual temperature of the heat sink, and that is easily done by allowing the KPA100 to cool (an hour or more) to the ambient temperature and setting the parameter to match the ambient temperature (in degrees C). If you think the fan is coming on too soon, you might try running the fan at the Hi/Lo setting rather than normal - the fan is not very noisy at low speed. Another solution is to add a muffin fan on top of the heat sink to draw air away from it - the means of keeping the fan in place can vary - if the KPA100 is not tilted, it will likely just sit there unaided, but if tilted, some fastening device may be required. You can see Tom Hammond's implementation at www.n0ss.net. The speed of an external 12 volt DC fan (salvaged from a defunct PC) can be slowed by inserting a series resistor. 73, Don W3FPR Jim Stoneback wrote: I searched the archives and didn't find anything on this, but from what I've read, I think I may have a problem with my KPA100. When operating CW the fan turns on high during every transmission and the heat sink gets hot to the touch. I'm a ragchewer so my transmissions do run to several minutes and, regardless of power setting, the fan will kick on high after several minutes of transmitting. Fan is set to 'nor'. Sending speed ranges from 15-20 wpm. Ambient temperature in the shack is around 74F. The fan has never kicked up to high when on SSB but I don't operate fone much, and generally don't talk for very long when I do. The K2/100 (recent build, sn 6194, KPA100 Version F1.10) operates well in all other respects. Does anyone have an idea what may be wrong? ___ 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 ___ 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
Re: [Elecraft] KPA100 Temp/Fan
Jim, I run alot of CW contests and with constant CQing/exchanges you could fry an egg on the heatsink. The existing cooling cannot keep up with the heat generated. It looks a bit Frankenstein but I mounted (with double back tape) a 12 volt 2.5 muffin fan on top of the heat sink. It runs cool as a cucumber now. This is now standard operating procedure for contests I run at 100w. Jay - KT5E Jim Stoneback wrote: I searched the archives and didn't find anything on this, but from what I've read, I think I may have a problem with my KPA100. When operating CW the fan turns on high during every transmission and the heat sink gets hot to the touch. I'm a ragchewer so my transmissions do run to several minutes and, regardless of power setting, the fan will kick on high after several minutes of transmitting. Fan is set to 'nor'. Sending speed ranges from 15-20 wpm. Ambient temperature in the shack is around 74F. The fan has never kicked up to high when on SSB but I don't operate fone much, and generally don't talk for very long when I do. The K2/100 (recent build, sn 6194, KPA100 Version F1.10) operates well in all other respects. Does anyone have an idea what may be wrong? ___ 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 ___ 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
RE: [Elecraft] KPA100 Temp/Fan
Have you calibrated the KPA100 temperature sensor and set the quiescent bias? The KPA100 has a self-protection circuit in it that reduces power and displays the message PA HOT if the heat sink temperature exceeds 85C (185F). I'm not sure it's possible to get the heat sink that hot in normal use, even the most long winded rag chews G. A few years ago I was part of a group testing the stability of the K2/100 over a wide range of operating temperatures. The test protocols included loading a message buffer with CW, then sending nonstop for between 30 and 60 minutes at 100 watts output. Under those conditions, in a shack with an ambient temperature of 24C (75F) the temperature of the cooling fins on the heat sink would approach 50C (122F). The K2 cooling fan was operating normally automatically switching to high above 37C (100F). No other cooling was provided. The tests were done dozens of times with no adverse effects on the rig. Eventually the heat sink temperature reaches equilibrium. The greater the difference between its temperature and the ambient air temperature, the faster it loses heat. When the loss of heat equals the heat being contributed by the amplifier circuits, the temperature no longer rises. The testing did not try to find this equilibrium. We were testing the effects on the heat on internal oscillators, not testing the KPA100 itself. My notes do indicate that the rise beyond 50C was very, very slow, however. That's why the tests stopped there. The rig was no longer heating appreciably. I mention the quiescent bias because the current the PA transistors are drawing key up also contributes heat. If it's high, that could lead to significant additional heating. Ron AC7AC -Original Message- Jim, I run alot of CW contests and with constant CQing/exchanges you could fry an egg on the heatsink. The existing cooling cannot keep up with the heat generated. It looks a bit Frankenstein but I mounted (with double back tape) a 12 volt 2.5 muffin fan on top of the heat sink. It runs cool as a cucumber now. This is now standard operating procedure for contests I run at 100w. Jay - KT5E Jim Stoneback wrote: I searched the archives and didn't find anything on this, but from what I've read, I think I may have a problem with my KPA100. When operating CW the fan turns on high during every transmission and the heat sink gets hot to the touch. I'm a ragchewer so my transmissions do run to several minutes and, regardless of power setting, the fan will kick on high after several minutes of transmitting. Fan is set to 'nor'. Sending speed ranges from 15-20 wpm. Ambient temperature in the shack is around 74F. The fan has never kicked up to high when on SSB but I don't operate fone much, and generally don't talk for very long when I do. The K2/100 (recent build, sn 6194, KPA100 Version F1.10) operates well in all other respects. Does anyone have an idea what may be wrong? ___ 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
