[TenTec] TT 238C will not tune

Steve Hunt steve at karinya.net
Mon Jul 29 05:06:25 EDT 2013


A number of points:

1) An "ugly" balun is a poor choice for use at the output of a wide-band 
tuner. It has high choking impedance over only a very narrow band of 
frequencies, and outside that narrow band the impedance is almost 
totally reactive; in some situations that means it can actually increase 
the CM current.

2) My 238 manual has a totally ambiguous statement about stringing the 
dial pointer. To start the process it says: "Run the inductor to the 
full clockwise stop (roller to the rear)". Actually, full clockwise has 
the roller to the front!!! Depending on whether you chose to go with 
"full clockwise" or "roller to the rear", you could end up with the 
pointer showing maximum inductance at zero or at 30.

3) The high attenuation figures for wet ladderline derive from the 
experimental work of Wes Stewart N7WS:
http://users.triconet.org/wesandlinda/ladder_line.pdf
The later experimental work by ARRL showed lower attenuation for wet 
ladderline, but the experimental method was soundly criticised.

Steve G3TXQ


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