Added Wire Antenna Question

[thinbluebbq]

HF wire antenna question but I preface with the knowledge I’m asking for opinions on the dark arts wherein there will likely be lots of opinions. 🙂

I currently have an inverted L between two large trees about 35-40’ up. The L is feeding a Flex with an Ameritron amp. I need to run a second wire antenna for a separate HF which will need to be online for constantly for a specific purpose. The supplied antenna is a 29’ long wire which feeds to an autotuner. Given my QTH configuration I have only a few options.

1) run it in the same orientation as the L just directly under it.
2) same orientation but parallel to the L
3) perpendicular to the L but at a lower height of about 20-25’

Is one superior to the other? Will any of them create problems for one or both radio? While the radios may receive a signal at the same time they likely won’t ever transmit at the same time.

Thanks in advance for the advice.

 

[G7RUX]

A bit more information is needed about what the second system will be doing. If you run the antenna wire close and in the same orie then you will see significant coupling; damage is possible. Perpendicular is preferred but it needs some spacing too.

 

[thinbluebbq]

A bit more information is needed about what the second system will be doing. If you run the antenna wire close and in the same orie then you will see significant coupling; damage is possible. Perpendicular is preferred but it needs some spacing too.

Perpendicular was my first thought. Would 10-15’ of vertical distance be enough separation?

Antenna 1 will feed a Flex and Ameritron amp and will run 100-600 on ham bands.

The new antenna will feed a radio putting out 100-150 watts on HF outside of the ham bands.

 

[prcguy]

I would keep the antennas quite a ways apart, mainly to protect one receiver while the other radio is transmitting with the amplifier. I had two wire antennas here, one 133ft that passed close to a tower and a sloping 10-20-40m wire at a right angle to the 133ft. When I transmitted with 1200w on 40m to the 133ft I could measure 10 watts of power being picked up by the 10-20-40 sloper. That will damage many if not most receivers. Had I been using 600w that would have fed about 6 watts into my other radio. Still very bad.

Its hard to say how far apart is safe but my guess is if the antennas are at a right angle to each other and 50ft or more apart its a good start. Whatever you do I would recommend measuring power into a dummy load on the antenna without the amplifier while transmitting on the other antenna with the amplifier. If you measure anything over about 100mw I would make changes to reduce the pickup even more.

 

[jwt873]

I can see problems using two radios running that much power to two antennas on the same property no matter how they're oriented.

When I was living in the city, I used to live right next door to another ham. His tower was only 60 feet from mine. When he was using 100 Watts on his 40 meter inverted vee, he would pretty well wipe out all the HF bands for me. I couldn't even use 10 15 or 20 meters with my 3 element Yagi. The same was true for him when I was transmitting.

We had to work out pre-arranged operating schedules, to avoid conflicts.

 

[prcguy]

I can see problems using two radios running that much power to two antennas on the same property no matter how they're oriented.

When I was living in the city, I used to live right next door to another ham. His tower was only 60 feet from mine. When he was using 100 Watts on his 40 meter inverted vee, he would pretty well wipe out all the HF bands for me. I couldn't even use 10 15 or 20 meters with my 3 element Yagi. The same was true for him when I was transmitting.

We had to work out pre-arranged operating schedules, to avoid conflicts.

I was talking about damaging a radio, its a given that trying to transmit and receive at the same time within a few blocks will probably wipe out receive on one radio.

 

[G7RUX]

Perpendicular was my first thought. Would 10-15’ of vertical distance be enough separation?

Antenna 1 will feed a Flex and Ameritron amp and will run 100-600 on ham bands.

The new antenna will feed a radio putting out 100-150 watts on HF outside of the ham bands.

Ah ok, that makes sense.
Perpendicular would be an absolute minimum I think and spacing needs to be as much as you can manage.
With two transmitters set up like that you are likely to be learning about intermodulation fairly quickly I would expect and I’m not sure that it’s going to be pretty.
You will likely need to make some effort to reduce the signals presented to each radio from the other and band filters might be the way to go here.

The setup you describe is probably going to be quite tricky to keep clean, unless you are very lucky.