NOTE: The exceptionally high values of CM resistance are likely due to
resonances below my measurement window which has run from 1 MHz through 50
MHz. In de-Qing with a shunt 4.7k carbon resistor, the curves become much
flater and values pretty much between 1k and 2k. I noted the K9YC's data
increased as he increased frequency. Mine did not. I asked why. De-Qing
is likely the reason.
So, in practice, is there enough loss in the system, likely mostly earth
losses, to effectively de-Q the chokes? Neither of my wires are more than
35-feet off soil surface (decaying upper Permian mudstones).
Was the data presented by K9YC bifilar wound chokes or coaxial cable wound
on the ferrite toroids? I suspect they are with bifilar wound chokes. I
also have to wonder if K9YC de-Q'ed his chokes for measurement?
Also, after winding and testing the 31 materisl with solid #12 solid copper
wire, I am beginning to believe the losses in the stranded wire chokes I've
wound and tested are djue to the insulation. I'm going to tear down the
#10 stranded 43 material choke and rewind it with the solid #12 wire with
wider spaced turns, maybe no more than 8 or 10 turns on 2 stacked cores of
3" OD.
I've also ordered a couple of the 4" 31 material cores from KF78P
Metalworks which will be wound with the #12 solid copper wire. More
updates coming.
PROBLEM with HOME BREW and TEST EQUIPMENT to MEASURE what YOU'VE
BUIILT.......... . . . NEVER SATISFIED............ All the chokes do a
good job of reducing the CM noise, but measurement shows the devil in the
details.....................
Dave - W?LEV
