2021 June, 26 – Starting with 80/160m RX antennas for 2021 winter season

June 26, 2021

After a careful reading of ON4UN‘s “LOW Band DXing” book, it’s time to start preparing the RX antennas for the 2021 winter season.
Here in Lapland, from the end of August, every moment is good for the first snowfalls and before then at least the beverages must be tested and spread.
For this first winter season in Lapland the project is to install:

  • Beverage NA – 400m
  • BOG NA – 120m
  • Snake JA – 150m
  • reference RX vertical by PA5WM
  • RX Active Loop by Cross Cuntry Wireless

Today I decided to start with the PA5WM vertical, recommended to me by IZ3BSU Giuseppe (Joe) during a phone call a few weeks ago, the original project can be found here

First I started with the input transformer (T1) with 4t+4t on binocular toroid #73 with 0.75mm enamelled copper wire.

I then twisted the loading toroid, PA5WM suggests in his project “about 38 windings on a FT114-61 ferrite in series with the vertical wire” but since we are “experimenters” and I don’t like to copy other people’s things .. I recovered a T240-61.
Toroid not so different from 114-61 just some turns less, but I didn’t want to wait for the next Amidon order it.
Initially I proceeded to wind 30+5 turns of 0.75mm enamelled copper wire in 3 groups of 10 turns each, leaving the last 5 almost free. I will connect the T240-61 temporarily to the support and to the input toroid T and I will check the resonance, I dont expect significant variations compared to the use of the T114-61 but the beauty is just experimenting.

dav

I then twisted the loading toroid, PA5WM suggests in his project “about 38 windings on a FT114-61 ferrite in series with the vertical wire” but since we are “experimenters” and I don’t like to copy other people’s things .. I recovered a T240-61.
Toroid not so different from 114-61 just some turns less, but I didn’t want to wait for the next Amidon order it.
Initially I proceeded to wind 30+5 turns of 0.75mm enamelled copper wire in 3 groups of 10 turns each, leaving the last 5 almost free. I will connect the T240-61 temporarily to the support and to the input toroid T and I will check the resonance, I dont expect significant variations compared to the use of the T114-61 but the beauty is just experimenting.

In “img1” you can see the completed box, the T240-61 has been positioned as close as possible to the connection point of the antenna wire and also the connection with the transformer T1 is as short as possible.
Only a small part of the empty box remains, perhaps enough, to hold a small preamp in the future.
In “img2” a photo of the upper part and of the anchor bracket to the support pole. I have chosen not to use a fishing rod as a support but to anchor the 6m long line to a branch of a tree so as to have nothing where snow and ice can attach and modify the resonance of the line.
Finally “img3” shows the complete box of the toroid fixing circle. Having to calibrate the antenna initially, and perhaps even later when the snow will have almost covered the box (here in Lapland it is not difficult to get to 150/200cm of fresh snow) I preferred a solution where I can operate on the coils of the toroid easily and a definitive fixing with glue or silicone would not have allowed me.