I think a "very fine hair" is being split here. When this "hair" is measured
in dB units instead of linear units the loses become insignificant. While
yes the old balanced match boxes are technically superior to the
differential mode match boxes common to the ham radio market today. I always
weigh discussions like this in terms of linear units vs. dB units.
In linear units the losses always appear larger than what they are in dB
units. As a EMI engineer by profession I do not worry as much about the
linear unit based losses until they become significant losses when measured
in dB units.
If you are talking about a 1/2 MW VOA transmitter - then yes you have to
address those loses, if you are talking about a ham running 900W to a zepp
antenna the losses are not as significant.
FWIW because of those "loses" the 4:1 balun I run is made by DX engineering,
it is rated for 160 - 10 meters @ 10kW. I chose this balun in order to avoid
coil saturation. The balun was spendy, but then in dB dollars I am ahead of
the game when compared to the purchase price of a kW rated balanced Johnson
matchbox which I think stops at 80 meters. Not sure if those old tuners are
designed for 160.
Just my two bits. Peace,
Don Jones KO7i
Arlington, WA
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|