A ladder line antenna "tuner" for HF
I want to use my 2 x 20 m (130 Feet) dipole for all HF-bands except parts of 160 m with a 450 ohms ladder line feeder to minimize feeder losses.
The further question is:
1. To buy an expensive manual/automatic antenna tuner (not loss free) or
2. To build/construct a cheap feed-extender (small losses)
In my case the choose is easy because my name is not 'Mr. Much Money' ;o)
Few tests shows the thoughts are well addressed and point forward.
After a study of W5DXP's article http://www.w5dxp.com/notuner.htm I understand the background of it and want to continue 'doing it in the right manner'.
Because my circumstances aren't as perfect as W5DXP's according height of antenna I cut the feeder length to 100 feet (~30 m) instead of 90 feet just to have the possibility to adjust it correct. Finally I ended at 82 feet ~25,05 m.
With 16 feet inserted in the tuner at 3730 kHz and low SWR I could adjust all HF bands to a proper SWR with the switches.
The switches I use are normal 2-wire power switches and 2 switches for each cable extension length.
Please find beneath my provisional antenna tuner with cable extension length of 1, 2, 4, 8 and 16 feet in step of 1 foot covering from 0 to 31 feed and it is sufficient for my use.
Last news: Operating at 60 m band add 7 feet (2.13 m) extra ladder line.
The physical size of the tuner is 20 x 23 x 72 cm³.
Link: Over view of my ladder line lengths
My balun consists of a Amidon FT-240-61 core
with ~ 12 turns 4 mm 'no name' Teflon cable and can easily withstand 1 kW HF.
The core is fastened with a few blobs of silicone.
New: I have added two serial coupled 47 kOhm/2W resistors over the twin-lead terminals to prevent static DC-voltage at receiver input caused by snow or rain weather.
The Balun inductance is 28 µH.
Later I will come back with additional information maybe a remote controlled version with relays.
Do you want some further information about my project please leave a mail.
03.11.2016: After a QSO with OZ8PK Per I have adjusted a serial condenser for 160 m to 570 pF (470 + 100 pF) and manual connect them between balun and tuner instead of one lead (only for 160 m).
All 5 switches down and only 2 W back).
THANK YOU Per!
Updated Sep 27 2011