[TowerTalk] Balun for Force 12 6 Element 20 Meter

[Grant Saviers]

My strategy is no coax connectors out on a boom.  Feedpoint ferrite 
chokes are in a PVC junction box with coax in thru a watertight gland 
and two glands out for short #10 leads to the feedpoint. So no exposed 
solder or connectors or nuts on plastic to loosen.

I've never figured out how to really make an S0239 watertight.  It rains 
a bit here in Seattle.

Grant KZ1W

On 7/21/2020 15:17, jimlux wrote:
> On 7/21/20 1:26 PM, Steve Maki wrote:
>> On 07/21/20 15:49 PM, jimlux wrote:
>>
>>>> I've seen similar issues and no longer depend on the normal bolt and 
>>>> nut shield connection when there is a layer of PVC involved which is 
>>>> compressed by the bolt & nut. Any shrinking of the PVC will cause an 
>>>> intermittent connection. Most commercial baluns are still made this 
>>>> way.
>>
>>> Or 4 nuts - nut1 wire nut2 pvc nut3 wire nut4
>>> The preload between nut1 and nut2  and the preload between nut3 and 
>>> nut4 are what make the contact. Takes two wrenches to get it tight 
>>> enough.
>>
>> I thought of that, but then you have a nut between the SO239 flange 
>> and the box. It starts getting messy. BTW just so we're on the same 
>> page - the connector flange is on the outside of the box, which is 
>> almost where it has to be for ease of assembly.
> 
> I was thinking of the *wire* connections (e.g. to the driven element) 
> where you'd have two studs that you'd hook a wire with a lug to.
> 
> 
> 
> 
>>
>>>> Instead I replace one of the 4 machine screws with a solid #14 or 
>>>> #12 wire that is soldered to the SO239 and sticks into the box 3/4" 
>>>> or 1", which the coax shield can then be soldered to.
>>
>>> That works fine for a coax connector, although now you've got a 
>>> "non-disconnectable" connection.
>>
>> The center conductor is soldered to the center pin, and the braid is 
>> soldered to the *ground pin*. What's not dis-connectable?
>>
>>> Actually, a banana jack/plug would probably work. They're spring 
>>> loaded, so they don't have thermal cycling issues.
>>
>> I realize now the OP was talking about the antenna/binding post side 
>> of the box. I haven't had a problem on that side, probably because 
>> there is a large flat washer on either side of the PVC.
> 
> Yes..
> 
> 
> 
>>
>> -Steve K8LX
>>
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