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Author Topic: screwdriver used for base ?  (Read 1572 times)
KE5HTB
Member

Posts: 15




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« on: April 01, 2013, 10:38:27 AM »

I have a screwdriver antenna I would like to setup for use at home.

I can not get it to tune anything at this point.
is is a ezglider I think is the name and is put out by the elpaso radio club.

it does all bands I need and did come with the bead for under antenna.
I have it on a 4x4 alum drain pan mounted center using a radio shack mount like was used for the old 102" whips without the spring on it .

All connections are tight and all.

I am wondering do I still need to lay radials to get this setup to work ? I wish to use 80-6 if possible but 80-10 I be happy as well.  I do have tuners to use if needed but prefer not to use them if I do not have to do so.
if I used 1 it will be the auto tuner in my ts-570dg radio. I do have manual tuners also if I had to do that.

Suggestions please.
ke5htb
fred
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VE3FMC
Member

Posts: 22




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« Reply #1 on: April 01, 2013, 11:23:45 AM »

I have a screwdriver antenna I would like to setup for use at home.

I can not get it to tune anything at this point.
is is a ezglider I think is the name and is put out by the elpaso radio club.

it does all bands I need and did come with the bead for under antenna.
I have it on a 4x4 alum drain pan mounted center using a radio shack mount like was used for the old 102" whips without the spring on it .

All connections are tight and all.

I am wondering do I still need to lay radials to get this setup to work ? I wish to use 80-6 if possible but 80-10 I be happy as well.  I do have tuners to use if needed but prefer not to use them if I do not have to do so.
if I used 1 it will be the auto tuner in my ts-570dg radio. I do have manual tuners also if I had to do that.

Suggestions please.
ke5htb
fred


Hi Fred

Try adding a counterpoise wire to it as the ground. Make it as long as you can, or add 3-4. A friend of mine uses that setup, he has a 250 foot counterpoise wire on his and it works 160-6 meters and works well. Not sure how high he has his mounted off the ground but I know it is off the ground.

I know another guy who has a screwdriver mounted at 30 feet on a tower. The tower acts as the ground, and his works well too.

Give it a try and see what happens. If your connections are good, coax is good then it should work.

73, Rick VE3FMC
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K0ZN
Member

Posts: 1763




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« Reply #2 on: April 01, 2013, 08:22:54 PM »


Keep in mind that the "ground" or "radial system" is literally the other HALF of that antenna.  With a short radiator, it is EXTREMELY important to have a good, low resistance ground system to minimize ground losses. Dr.Jerry Sevic, W2FMI, did several studies of short radiators and their ground systems and conclusively proved the importance
of a good, low resistance ground system with small/short radiators. W2FMI is considered one of the real guru's in transmission lines and short antennas. Short version: the radiation resistance of short radiators is very low, consequently ground resistance has to be kept low to avoid losses. Respectfully, pick up a copy of the ARRL Antenna Book
and put in a little study time; the knowledge gained will pay back many times over. Antenna theory is not complex, but it is also not forgiving of assumptions and guesses.

73,  K0ZN
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M6GOM
Member

Posts: 1050




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« Reply #3 on: April 02, 2013, 04:20:38 AM »


I am wondering do I still need to lay radials to get this setup to work ? I wish to use 80-6 if possible but 80-10 I be happy as well.  I do have tuners to use if needed but prefer not to use them if I do not have to do so.
if I used 1 it will be the auto tuner in my ts-570dg radio. I do have manual tuners also if I had to do that.

Suggestions please.
ke5htb
fred


Yes you need radials. No you do not EVER use a tuner with a screwdriver antenna - you'll kill the coil. You adjust the antenna to get the lowest SWR, not use a tuner.
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K6JHU
Member

Posts: 27




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« Reply #4 on: April 02, 2013, 08:16:00 AM »

I use a screwdriver, ground mounted. I also have (since I have space) 33' radials about 2" below ground (to keep the critters from the wire). There are several articles out there on the numbers and types of ground radials. But... YOU NEED GROUND RADIALS for a screwdriver mount. Bascially, the longer and the more, the better.
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WN2C
Member

Posts: 546




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« Reply #5 on: April 02, 2013, 08:30:28 AM »

Check out k7jq's pics on QRZ and you will see how he has his set up.  A pic is worth a 1000 words.

Rick  wn2c
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