[RFI] tips on building common mode chokes

bill K7WXW K7WXW at qrpdx.org
Wed Oct 31 14:56:14 EDT 2018


I am building a set of feed line common mode chokes to test in my shack, 
using K9YC's published test data and charts (mahalo, Jim!).  Since the 
chokes will be inserted into existing feed lines, each choke, wound on a 
type 43 or 31 2.4 inch toroid, will be terminated with SO239 and PL259 
connectors.  I run 200W maximum though my normal operating power is less 
than twenty.

The bifilar chokes use #14 or #12 THHN wire. I can install a PL259 
solder connector designed for LM400 pretty easily on either but the 
SO239 side of things is giving me fits. I just can't figure out how to 
nake a solid solder connection with wire this size and the standard 
SO239, whether in bulkhead or panel mount form.  Is there some version 
of the connector I just haven't managed to locate? Some trick to getting 
big wire in a small hole? I've been staring at photos of other people's 
chokes for a couple of days and haven't figured it out.

I will also be making coax versions with both toroids and the clamp on 
ferrites though I am inclined to the bifilar versions based on Jim's 
data. The idea is to compare them all side by side in operation and see 
which work the best in my situation. I'd also test them on a vector 
analyzer if I had one, but alas I don't.

Thanks in advance!  73 de bill K7WXW

______________
brevity is beautiful.


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