Thanks for the feedback, guys.
One picture is worth a thousand words. Below is a picture of the choke balun.
It is going to be attached to a T shaped Lexan plate for an inverted V center
connection.
The RG-400 runs inside the PVC pipe and connects to the SO-239's at each end.
I am worried about condensation inside and was planning on pumping it full of
dielectric grease.
Maybe just simply drilling a weep hole in the bottom end so it can breath and
any dry out any condensation would be sufficient.
https://i.postimg.cc/QtFCSc90/IMG-2754.jpg
<https://i.postimg.cc/QtFCSc90/IMG-2754.jpg>
Bob
K6UJ
> On Sep 22, 2019, at 3:44 PM, jimlux <jimlux@earthlink.net> wrote:
>
> On 9/22/19 2:24 PM, Grant Saviers wrote:
>> 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.
>
>
> WHy not use some form of fiberglass tube? McMaster has it in all sizes and
> shapes that would be suitable.
>
> Yes, glass is somewhat lossy at microwave frequencies, but this is for a HF
> antenna.
>
> Or choose a traditional material like linen or paper phenolic.
>
>
>
>> 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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