RAST Forum

Ham Radio in Thailand => HF => Topic started by: hs0zfe on April 29, 2012, 07:24:59 PM

Title: End-Fedz 10-20-40 m antenna for 25 Watts and a copy for 200 Watts
Post by: hs0zfe on April 29, 2012, 07:24:59 PM
http://pa-11019.blogspot.com/

what's your opinion of this stealth antenna? The 25 Watts version costs $ 75.

73,
Chris HS0ZFE
Title: Re: End-Fedz 10-20-40 m antenna for 25 Watts and a copy for 200 Watts
Post by: DaveUdon on June 07, 2012, 03:18:06 PM
Hi Chris,

What a great website, lots of good ideas there.
I find the european sites to be very thought-provoking in the antenna subjects.

As to your question, the smaller physical size antenna at the same current means less radiation efficiency and more loss as compared to the theoretical free-standing dipole. The higher losses could mean more heat, so stand well back, mind the arcing, and keep the amp turned off!

But seriously, at lower power levels with matched inductive and capacitive voltages at the feedpoint (low swr at a given freq), you'll see the radiation you wanted: how much depends on the amount of metal hanging out there, plus a few environmental factors.

I enjoy all your posts...

Thank you and 73,

Dave in Udon  HS0ZGR

Title: Re: End-Fedz 10-20-40 m antenna for 25 Watts and a copy for 200 Watts
Post by: G0MIH on May 14, 2013, 06:13:51 PM
Hi Dave.

Yes I agree with you. If the Z0 of the antenna is very high the voltage will be high too so the safety side of things need to be looked into.
I have worked on many high power TX site where the voltages are so high it will flash over when it gets wet. I have also seen the same thing on low power site as well as the mast Z0 was so high the voltage was up the 10KV range with only 100 watts.
So be careful.

Paul G0MIH.