Hello the list,

   I have been experiencing heating problems with my step-down toroidal 
transformer that feeds my transmit loop. Fearing core saturaton issues I have 
been going to ever larger cores and more and more turns in an attempt to reduce 
the flux density.  My latest core is 4 stacked 4" diameter Mix 78 toroids 
weighing a total of 3 pounds (1.34 Kg) with 28 turns of #10 on the 50 ohm 
winding and 5 turns of 16 mm2 wire on the loop side.

 Now for the puzzle: As suggested by J.B., I hooked two transformers back to 
back ; the present transformer (described above) and the previous model (4 
stacked FT-290-77 toroids with 17 turns on the 50 ohm side and 3 turns on the 
loop side.  I connected the two transfomers with the the loop windings from one 
going into the loop winding of the next. One transformer 50 ohm winding was 
hooked to a 50 ohm Bird Dummy Load, the other transformer's 50 ohm winding went 
to an AEA VIA impedance bridge.  Much to my surprise I had a high swr and 
reactance !!!
The swr was on the order of 2.7:1 and the reactance was 45-55 ohm and 
increasing with frequency.

 Any thoughts on why I should show a reactive component when one transformer 
went directly to a 50 ohm load?



--
73 Warren K2ORS/WD2XGJ
FN42hi
http://www.w4dex.com/wd2xgj.htm