I've also heard that the native impedance a twisted pair of WD1A/TT
is about 150ohms. In my application, I use two parallel lengths of
WD1A/TT, spaced about 4.5inches. Each twisted pair acts like a single
conductor, and the Z of the two parallel lengths is about 450 ohms.
I didn't know the variants of WD1a used different conductors. My
earlier comments refer to the twisted pair variant, with each
conductor comprised of a mix of fine steel and copper strands.
73,
Jim w8zr
Sent from my iPhone
> On May 9, 2020, at 6:16 PM, Mike Waters <mikewate@gmail.com> wrote:
>
> Exactly, Dave! It's right in my Beverage antenna page ("145 ohms"), along
> with several different calculators. :-)
>
> And all WD-1* wire is *not* the same. Back when I used to sell Beverage
> transformers, people would send me short samples to measure before I wound
> them. You have to accurately measure the spacing and wire diameters to
> determine that, unless you have a long enough piece of it to use an antenna
> analyzer (preferred).
>
> The 6.25:1 is okay for the feed end, but NOT the reflection transformer. I
> corrected that on the former w0btu.com, but the archived page implies
> otherwise.
>
> 73, Mike
> W0BTU
>
>> On Sat, May 9, 2020, 6:52 PM Artek Manuals <Manuals@artekmanuals.com> wrote:
>>
>> More like 150 ohms as I recall
>>
>> Dave
>> NR1DX
>>
>>> On 5/9/2020 7:34 PM, Mike Waters wrote:
>>> Fred, those transformers are the wrong impedance ratio for WD1! They are
>>> for 420-450 ohm wire. WD-1 has a much lower impedance.
>>>
>>
>>
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
|