BTW, Jim The fact that you can't get the feed-point resistance above 27 ohms, sounds like you are just looking at the driving-point resistance of the inverted L in parallels with the inductance of the matching coil, that is large enough that it's out of the picture. Can you use a grid-dip meter to see where the inverted L is resonant with the matching coil in place?
Also, a toroid core for the matching coil would be a really bad idea for two reasons: 1. At full power on 160, there would be several amps of RF current flowing through the matching coil. That makes core saturation rather likely. 2. Even without core saturation, you would be burning power heating the toroid core, creating losses that you don't need. 73. Charlie, K4OTV -----Original Message----- From: Topband [mailto:[email protected]] On Behalf Of Jim GM Sent: Saturday, September 14, 2013 1:14 AM To: topband Subject: Topband: Hairpin Matching Coil Questions I have an inverted L and using a hairpin coil to match in on 160M. One coil is 6 inches OD the other is 2 inches OD. I have been thinking about making another hairpin with wire wrapped around a toroid donut, I have noticed with the 6 inch coil I have a higher noise level on 160M and hear BCI pretty strong on certain frequencies on other bands. The 2 inch coil has lower noise level on 160M and BCI is reduced on other bands. If I use a toroid hairpin What would happen to the noise level and BCI? My guess is both will be reduced a bit more. Also what hairpin matching coil should I use and why? -- Jim K9TF _________________ Topband Reflector _________________ Topband Reflector
