22 decembrie 2015

Portable HF antenna setup

Well, the winter is coming (at least when I peek to the calendar) so it's time to make the antennas for portable HF.
I am using an ICOM IC-703+ with the ICOM backpack and a vertical Racal antenna. But this is not enough for me so I planned to experiment with an End Fed antenna.
I contemplated the End Fed Half Wave antenna with a high ratio UnUn but the tests I did on my lab didn't convince me. I also find the lenght of the EFHW not suitable for what I expect from a portable setup. It's simply to lenghty to use it on various setups, mainly to keep it at the necessary height from the ground.
So, the next choice for a multiband wire antenna is also some sort of End Fed but the one that can be fed with a 9:1 UnUn, an aperiodic one.
On the internet there are several places where you cand found a suitable lenght for the wire.
As I am not interested on 160m band from portable, I choose the 13.5 m as the best for me.
I quickly made a 9:1 Unbalanced to Unbalanced broadband transformer and a 1:1 choke Balun made from a piece of RG316 teflon coax on a FT-120-43 toroid core. This consist of 4+4 turns on the ferrite core.
I prepared two pieces of RG58 coax cable. One of 10m and the second one of 5m.
I can use the choke balun to make a counterpoise from the 5 or from the 10m of coax cable. If the conditions permit, I cand put a real counterpoise directly on the 9:1 BalUn and use the entire lenght of the cable with a UHF Female-female adapter without the choke balun. Or even to use the choke balun right at the transceiver's output.
So, I believe this setup let me experiment in the field with the best setup from various ones.
I will revisit this post after the Christmas holiday.
Merry Christmas!

 I forgot, this is a small Z-Match made with polyvaricons. This is to be used with 450 Ohm ladder line and simmetrical dipoles.

QRP Z-matchbox

9:1 QRP Bal-Un

Prerequisites for 1:1 choke balun

9:1 BalUn inside

9:1 BalUn inside

Portable EndFed setup

Portable EndFed setup

Portable EndFed setup - detail

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