[TowerTalk] Dielectric Grease

[jimlux]

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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