[TowerTalk] Using Stubs to Reject Harmonics

[Jim Brown]

On Tue, 2 Feb 2010 13:49:36 -0600, Tim Duffy K3LR wrote:

>Hi Jim:

>I always wanted to test the 1/4 wave "insertion" theory, but never got
>around to it. I would love to hear what the difference is - if you can
>experiment.

Hi Tim,

OK. As noted, my Titan 425s (original) are not a good output stage to 
test this, but I've got a Hercules II that does use a traditional pi-
section (C-L-C) as the output filter. When I have time, I'll set that up 
and see what I can learn. But as I said in an earlier post, I find no 
flaws in Tom's logic. 

Note, however, that Tom's logic applies to TX. RX is a different story, 
so a stub tuned to reject a TX on the band below (that is, an 80M reject 
stub on a 40M line) should be fairly effective near the RX input. I say 
"fairly effective" because RX inputs are not always well matched to the 
lines that feed them. :)  

73,

Jim K9YC