Help me Diagnose/Repair 9:1 Random Wire Antenna?

[lumbergh]

I am licensed but inexperienced. I bought a end-fed random wire antenna with the 9:1 balun.

It held up poorly over the year. The wire is nearly torn apart, and of course I can replace that easily.

But I am not sure it was ever working, and I don't know how to test the Balun to be sure.

I don't have much equipment but I have a rig with tuner (but I don't know if it's good), I have basic tools and hopefully common sense.

Can you prescribe an afternoon of to-dos that will get me to the bottom of this?

 

[prcguy]

A 9:1 balun will transform 50 ohms to 450 ohms over a wide frequency range. Connect a non inductive 450 ohm resistor from the antenna side of the balun to ground side of the input then test with an antenna analyzer, VSWR should be very low over the rated frequency range and that will tell you if the balun is ok.

 

[lumbergh]

A 9:1 balun will transform 50 ohms to 450 ohms over a wide frequency range. Connect a non inductive 450 ohm resistor from the antenna side of the balun to ground side of the input then test with an antenna analyzer, VSWR should be very low over the rated frequency range and that will tell you if the balun is ok.

Great answer, thank you. Can you think of a way that doesn't require an antenna analyzer? I don't have access to one, and they're quite expensive.

 

[prcguy]

Great answer, thank you. Can you think of a way that doesn't require an antenna analyzer? I don't have access to one, and they're quite expensive.

If you can find a non 450 ohm inductive resistor that will handle 10w of power you could use your radio and an SWR meter to map it out. It should have a great match across the entire rated frequency range. Just don't feed it more than about 10W during testing and make transmission brief.

 

[lumbergh]

If you can find a non 450 ohm inductive resistor that will handle 10w of power you could use your radio and an SWR meter to map it out. It should have a great match across the entire rated frequency range. Just don't feed it more than about 10W during testing and make transmission brief.

Okay! So three follow-up questions please:

1. I want to purchase a "non-inductive 450 ohm resistor, 10W" right?
2. Will a CB radio SWR meter work for this? At minimum it should work for 10-11m on the rig, but otherwise? (Assuming it can handle 10W, which I'll have to check.)
3. How is this hooked up? Where does the resistor even go?

 

[prcguy]

Okay! So three follow-up questions please:

1. I want to purchase a "non-inductive 450 ohm resistor, 10W" right?
2. Will a CB radio SWR meter work for this? At minimum it should work for 10-11m on the rig, but otherwise? (Assuming it can handle 10W, which I'll have to check.)
3. How is this hooked up? Where does the resistor even go?

If you can reliably put out low power like 2W then you can use a simple 2W carbon resistor which is non inductive. Or a 10W power resistor that is wire wound (inductive) might work to some extent. A CB type SWR meter should work fine. You connect the radio and SWR meter to the transformer using short coax jumpers then one end of the resistor goes to the antenna wire terminal on the transformer and the other end of the resistor goes to the ground side of the input which would be the SO-239 connector where the radio and SWR meter are connected.