Hi Evert, First, sorry I missed you in the PACC! I played a little in it, 160 to 20.
As to your questions: 1) Is there a noticeable difference in heat-sink temperature when operating on higher bands? There is a noticable difference if you're running into a mismatched load. Also, it gets pretty warm if you're working at a high rate or sending endless CQs. (Thant's a good time to go Search and Pounce and give the finals a break). 2) Can this amplifier be tuned for 1 hour on a dummy with full output at any band without any semi-irreversible side effects? I don't know, never tried it. I've run mine pretty hot for hours in the 160M tests. Warm to the touch, but not painful, I try to place it in the drafty part of the bench ;o) 3) I'm used to big tube amplifiers which need air-flow "throughput". The fan in the K2 is blowing into the box but there is no way out (kind of short circuit in terms of air flow). What is the reason for this cooling fan to blow into the box instead of making "forced" airflow through/along the heatsink. It looks to me that some extra holes into the cabinet might raise the efficiency of cooling dramatically (inside the box... This has been discussed on the reflector a number of times in the past. I'm not sure that anyone has added vents to the cabinets yet. Some have placed added fans on the top of the rig, I haven't yet. It is my understanding the power transistors are much better designed and able to deal with some pretty impressive heat loads when properly sinked. Glass envelope tubes are more vunerable to heat. The 2 most important reasons for electronics to stop functioning is over voltage/current and temperature stress by cooling - heating - cooling - heating etc. Even if the heating is within the specs, the overall product life is degenerating quickly by extremely temperature changes. It also stresses the solder point on the PCB. In general: Is the K2 designed to operate at full specs during contests/expeditions under any normal environmental condition (0 deg C to 40 deg C) without cooling down periods? In the couple years I've been on this reflector and using a K2/100, I've yet to hear of anyone losing the final transistors for either contests or DXpeditions. There are a number of us who are serious contesters and K2's have been used on several major DX operations. Some folks have seperated the KPA100, for various reasons, this would probably improve the heat situation as well. Several have added fans, I've thought about it, but haven't yet. 73, Julius n2wn K2/100 #3311 _______________________________________________ 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
