[Elecraft] Dummy loads for dummies

Edward R Cole kl7uw at acsalaska.net
Wed Dec 28 03:26:20 EST 2016


http://www.kl7uw.com/2M80_inside_1.jpg

In the photo the large black square at bottom of the pc board is a 
surface-mount 56-ohm 35w resistor (good at 2m) and available from 
Mouser.  I believe there were 51-ohm values also.  This used in a 
23-dB pi-attenuator to take 10w down to 50mw for driving a Toshiba 
SAV-36 RF amplifier module in the 80w 2m amp that I build.  W6PQL 
sells 150w surface mount loads that are good at 1296 MHz.  All you 
need is a small pcb and a large heat sink.

TO-220 form probably more convenient as one can mount them directly 
to a heat sink with a tapped hole for a 4-40 machine screw and using 
a little heat sink compound.  If the heat sink is large enough air 
cooling is sufficient.

I have a big old Sierra Electronic 500w coaxial load with heat sink 
and built in power meter; weighs about 40-50 lbs; makes a dandy door 
stop, too!  It is rated to 1000-MHz.  Got in trade somewhere?  I 
would not want to pay retail for one; probably in range of $2/watt.

73, Ed - KL7UW
   http://www.kl7uw.com
Dubus-NA Business mail:
   dubususa at gmail.com 



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