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-   -   Anyone recommend a source of 36:50 ohm ununs? (https://www.radiobanter.com/antenna/226119-anyone-recommend-source-36-50-ohm-ununs.html)

John S July 28th 16 03:37 PM

Anyone recommend a source of 36:50 ohm ununs?
 
On 7/28/2016 3:03 AM, Ian Jackson wrote:
In message , John S
writes
On 7/27/2016 4:43 PM, Ian Jackson wrote:
In message , Robert Smits
writes
Thanks for all the suggestions.

I'll see what it's like with 50 ohm coax first, and then make other
changes.

What about making the antenna somewhat longer than a quarterwave (which
presumably is what it is)? This will make the feedpoint impedance higher
resistive, and inductive. Make it long enough to get the resistance
close to 50 ohms, and then add series C to cancel the inductance.


Or, rather than fussing with the antenna, just use a 50 ohm .051
wavelength open stub located 0.113 wavelengths from the antenna. Use a
T-connector. Wavelengths are electrical lengths. Good for 1.8Mhz.

Feel free to check my numbers.


I'll believe you, as my Smith chart skills are rusty at the moment!

However, has it been determined why the OP wants to try and achieve a
perfect match?


Not entirely. Something about running "barefoot".

If it is to reduce losses in the coax, unless the coax is really long,
on 160m the losses due to having a 2:1 SWR are probably negligible.


Very true. And, actually, would be less than 1.4:1 SWR if his numbers
are correct.

If it is to present the TX with a perfect 50 ohm load, this can be done
at the shack end with the appropriate simple matcher.


Also very true. Much easier to adjust and maintain as well.


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