14-10-2018, 07:07 PM
Peter
There will be losses but what will happen is the ALC will drop back the RF power in the rig due to internal SWR sensing the high inherent SWR. An in-line tuner can negate the mismatch but it introduces losses too.
Modify the 9:1 balun to optionally give you 1:1 and use a switch / relay / jumpers / cliplead arrangement to allow you to change the ratio depending on which band is is use. That is assuming that "ground level" is actually reachable if doing it manually.
Typical 9:1 balun wiring is like at http://www.spirat.com.au/vk5zvs/pic31.htm but add another 2 x 3-turn windings so that you can have a 1:1 output from the same balun core, centre joint of the 2 x 3T to ground....
Switch both feeder legs from the 9:1 to 1:1 outputs - use a DPDT relay to achieve it remotely.
You might even find that the variability of the two impedance selections will let you use the antenna on other bands as well.
There will be losses but what will happen is the ALC will drop back the RF power in the rig due to internal SWR sensing the high inherent SWR. An in-line tuner can negate the mismatch but it introduces losses too.
Modify the 9:1 balun to optionally give you 1:1 and use a switch / relay / jumpers / cliplead arrangement to allow you to change the ratio depending on which band is is use. That is assuming that "ground level" is actually reachable if doing it manually.
Typical 9:1 balun wiring is like at http://www.spirat.com.au/vk5zvs/pic31.htm but add another 2 x 3-turn windings so that you can have a 1:1 output from the same balun core, centre joint of the 2 x 3T to ground....
Switch both feeder legs from the 9:1 to 1:1 outputs - use a DPDT relay to achieve it remotely.
You might even find that the variability of the two impedance selections will let you use the antenna on other bands as well.
Doug VK4ADC @ QG62LG51
http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.
http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.