| The extra dielectric is going to increase the stray capacitance and the 
PVC has loss.  So expect a lower self resonant frequency and more loss. 
I'm trying to make some high Q coils and conclude PVC pipe is a poor 
form, even machined into a skeleton support.  That's CW but I thought a 
skeleton might be ok - NOT.  I think grey PVC is grey in part to a clay 
filler to make it UV resistant. 
Then a challenge is the grease should have very low moisture absorption 
or the (I suspect) reason for it is negated or worse. 
On my RG400/316/179 etc pigtail ends I apply a little red insulating 
varnish which wicks into the braid amazingly far.  The plan is to 
prevent water from wicking.  A downside of TFE coax is almost nothing 
will stick to it.  I also apply the varnish around all bulkhead 
connector flanges and screws. 
Grant KZ1W
On 9/22/2019 11:46 AM, Robert Harmon wrote:
 
I am making a current balun with a 2.4" OD Fair Rite core wound with RG-400.  
PVC pipe is going thru the center and the RG-400
is routed thru the inside to SO-239's in PVC pipe caps on the ends.    I am 
planning on flooding the choke with dielectric grease
before completing the assembly and I'm trying to decide what dielectric grease 
to use.   What would you use ?  Super Lube is supposed
to be a dielectric greae, would it be suitable ?
Bob
K6UJ
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