Re: KAT500 update

Posted by Ignacy on Dec 09, 2011; 1:40am
URL: http://elecraft.85.s1.nabble.com/KAT500-update-tp7072932p7076631.html

W8JI and other sites assume that the balun is lossless except for common mode. Also that voltage breakage is unimportant. Both are good approximations when the balun is large and wound by thick wire or with teflon cable.

Assume we use RG174 for windings.  We have SWR 1:1 on input and 25:1 with 2500 Ohm input. Thus 25 lower power ratings on output than on input. Could be 100W max with balun on on input and 4 W max with balun on output.

One can always substitute a bigger coax (increase the balun size a few times), or use bifilar windings (and worrying about insulation breakage). Summarizing, a $2 balun on input would be as effective as a $50 balun on output, and 10 times lighter. Not important for stationary equipment but important when portable.

For KAT500 its is better to use a $50 balun as otherwise switching would cost more.  

Perhaps this thread is no longer relevant to KAT500 and needs to be terminated.

Ignacy