Im in the middle of some CM experiments..using a single large clamp on, in
addition
to some 2.4 inch od cores. For interest, I connected my B+K 875-B digital
lcr meter
to the shield at each end. These large clamp ons are a six sided affair, on
the outside.
I measured 120 uh with just the torroids. That increases to 137 uh with the
addition of
one large clamp on. However, with one side of the big clamp on, firmly
against the inside
of a thermoplastic box, and squeezing really hard on the opposite side, the
inductance increased
to as much as 157-158 uh ! Let go, and it drops back down to the 137 uh
region. In both cases
the hinged section was shut solidly. Ok, so what gives here ? My plan was
to use 2-3 x ty raps
and tighten the clamp on really good.
## I think the issue is the mating surface gaps on the hinged portions.
There is a pair of mating surfaces
at the 9 oclock position..... and another pair of mating surfaces at the 3
oclock position. In this application, there
is only 3 turns of RG-393 passing inside the big clamp on, so there is room
for the 3 turns with no fitment issues.
The ID of these large clamps ons is 1 inch.
## Is this normal for these large clamp ons ? I have never used them b4. I
was thinking of 88 tape to keep em
firmly closed, but 2-3 wide ty-raps can be cinched up a lot tighter than any
tape job. Or do I use one wrap of tape
1st, then a ty-rap dead centered on the tape job.
Jim VE7RF.
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