[Elecraft] Underside of K3 getting very hot when transmitting
My K3 100W ser. 1343 gets VERY hot on the underside where the PA transistors are connected to the chassis. I´m testing at 100W FM into a dummyload for about 3-5 minutes. Is that normal? Vy 73 Jens OZ9MZ ___ 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] Underside of K3 getting very hot when transmitting
It is normal - depending on what you mean by "very hot". Very hot to the touch could be 60C. Very hot to a PA device might be 90C or more. It is a good sign your transistors are thermally bonded to the case. I am not sure you are really supposed to use high duty cycle modes for extended periods like this. The manual mentions reducing power on 100% modes like FM. Using the bottom of the case for cooling generally works OK for low duty cycles but might need help for 100% modes. My 2m and 4m XV transverters use relatively inefficient PA modules and so also get hot during extended contesting. I found a small waft of air from an appropriately positioned computer fan sufficient to prevent excessive heating. You might try this with the K3. It takes very little air because the surface area is large and you are only dissipating a few watts. Mike Jens Køster wrote: > > My K3 100W ser. 1343 gets VERY hot on the underside where the PA > transistors > are connected to the chassis. I´m testing at 100W FM into a dummyload for > about 3-5 minutes. > > Is that normal? > > Vy 73 > > Jens > OZ9MZ > ___ > 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 > > -- View this message in context: http://n2.nabble.com/Underside-of-K3-getting-very-hot-when-transmitting-tp1082012p1082061.html Sent from the Elecraft mailing list archive at Nabble.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] Underside of K3 getting very hot when transmitting
Jens Køster wrote: My K3 100W ser. 1343 gets VERY hot on the underside where the PA transistors are connected to the chassis. I´m testing at 100W FM into a dummyload for about 3-5 minutes. Is that normal? The K3 isn't rated for 100W on FM or any other continuous duty mode, according to the latest manual. "*CW and SSB modes,* 100% 10-min. 100W key-down at 25 C ambient" You must turn the power down on FM and AM or you will burn the finals up. -- R. Kevin Stover, AC0H K2/100 #4684 ARRL SKCC #215 FISTS #11993 ___ 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
