[TowerTalk] solid THHN vs jacketed copperweld

[Steve Maki]

I my case I had insulation on both wires, so I was mainly interested in 
the VF difference between solid copper and copperweld at 3.5 MHZ.

I had sworn off copperweld many years ago after noting that the copper 
plating did not last forever. But I recently discovered that there is an 
insulated version which is marketed to directional borers to pull in 
outside of the conduit as a tracer wire.

The PVC should protect the plating...at least until it falls off.

-Steve K8LX

On 9/20/2022 1:10 PM, Grant Saviers wrote:
> The dielectric loading of insulation makes the wire electrically longer 
> for RF.  EZNEC can model it, if you know the dielectric constant 
> (usually around 3 for PVC, nylon) and thickness.
> 
> The height of the dipole has a larger effect.  Plus for 160 & 80 quality 
> copperweld is needed with thick copper, so the internal field (skin 
> depth) is in the copper, not in the steel which will cause high losses.
> 
> Grant KZ1W
> 
> On 9/19/2022 14:56, Steve Maki wrote:
>> Wondering whether there is any substantial difference between #12 
>> solid THHN and #12 PVC jacketed copperweld (steel) in terms of cutting 
>> a dipole to length.
>>
>> I'm in the process of installing a K8UR style 80M four square. I 
>> trimmed the first element to length using THHN. Then I decided that I 
>> should use steel wire for at least the top half of the elements 
>> because of the high wire tension I ended up with after pulling the 
>> feed-point out far enough from the array center. It's an issue with 
>> not enough acreage around the tower.
>>
>> Even so I ended up with a 50 ohm antenna rather than the desired 30-40 
>> ohm antenna per the DXE instruction manual. But that's an entirely 
>> difference issue (though I'd appreciate any comments on that as well).
>>
>> Should I expect the steel wire lengths to be pretty close to the THHN 
>> lengths, or should I re-do the initial step of carefully cutting the 
>> first element in isolation?
>>
>> TIA!
>>
>> -Steve K8LX
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk