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Author Topic: New Station  (Read 839 times)
KC9LXW
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Posts: 25




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« on: November 26, 2007, 04:39:19 PM »

Hey fellow hams I just got into about a couple of months of go and I love it so much I decided to upgrade to a General Class but since I'm only 15 the budget is a little tight so I was looking at the IC-718 as an begginer rig would you guys think that would be a good choice?  Also I have been looking aat some vertical antennas because I have to comprimise with my parents if I even want an antenna because I did want a wire antenna but they didn't like the idea of having an wire around the yard do you guys think going vertical would be my best choice if I mount it on top of a TV tower antenna?  If so I've been looking at the hy-gain AV-18AVQ which operates on 10/15/20/40 bands but for an extra $60 I can get all of those bands plus 80 meters, would this be worth the money and are the bands really active or is there some bands that I will be missing out?  Also last question what all other equipment do I need to get me on the air other than the radio and antenna?
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N0RZT
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Posts: 104




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« Reply #1 on: November 26, 2007, 06:22:23 PM »

Good evening,

The IC-718 is an excellent choice - it's my primary rig.  There are a couple of features that I wish it had, but they're "nice-to-have" not "necessary" and are found only in rigs more than twice the price.  If you're going to work CW, a CW filter is a must.  You can get by without an SSB filter.

I have no opinion on the performance of the hy-gain antenna.  When you install it, try to borrow an antenna analyzer from someone at your club (better yet, offer to trade a hot lunch in exchange for their help setting up your station) - tuning the antenna will go MUCH faster with an antenna analyzer than with the old standby of keying the radio and checking SWR.

Something to remember about elevated vertical antennas - they need resonant radials for every band you plan to use.  If your parents object to those wires, ask if ground-mounting it is acceptable.  If your parents don't object to those wires, re-address the question of a wire antenna, using the tower as the central support.

73,
Chris
N0RZT/8
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ONAIR
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Posts: 1737




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« Reply #2 on: November 26, 2007, 10:20:29 PM »

    Congrats on the enthusiasm!  The 718 is a great rig for the beginner, and many seasoned hams are delighted with them as well!  You can homebrew your own coaxial bazooka verticals for 10 and 20m, and you won't need radials for them. (plus they are very inexpensive!)  Maybe you can maneuver your parents into an inverted L or V for the lower bands, or see if they'd be OK with a vertical antenna with a bunch of radials buried around it out of sight!
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AB8XA
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Posts: 30




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« Reply #3 on: November 27, 2007, 04:35:31 AM »

The IC-718 is an excellent rig.  It uses 13.8 volts DC, 20 amps of it on transmit, so you'll need a power supply to convert the 120 VAC from your wall outlets to that.  Look for a supply with a 20-25 amp continuous rating.  I, and others, successfully use an Astron RS20A with the IC-718, even though it's only rated 16 amps continuous and 20 amps peak.  In my case, I had it on hand, but in yours, when buying new, get a larger one.

Most verticals need radials to perform well.  Elevated verticals need 4 for each band, cut to a specific length.  It's likely your parents will like this a whole lot less than wire antennas.  With the antenna ground mounted, radial length is much less critical, generally only need to be as long as the antenna is tall, and can be buried or just stapled to the lawn which will grow over them.

Depending on your location/weather and how well shielded from the wind a vertical would be, it may also need guy lines.  3/32" Dacron coming down 45ยบ works well for that.  Again, probably not something your parents will like.  

If you go with a multiband doublet or end fed wire antenna, you'll need a tuner.  The Icom AH-4 works well with the IC-718 for that.

Hope this helps.
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KC9LXW
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Posts: 25




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« Reply #4 on: November 27, 2007, 03:49:04 PM »

Ok now I was a bit confused about the radials that you guys mentioned and I was wondering do I put them at the base of the antenna or at the base of the tower, because I'm going to mount the vertical antenna on top of an old TV antenna tower.  
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WB2WIK
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Posts: 20595




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« Reply #5 on: November 27, 2007, 06:05:13 PM »

Radials always connect directly to the *antenna*, not the tower.  Radials connected to the tower in your case will serve no purpose: They connect to the base of the antenna, and fan out (and can slope downwards below horizon) from there.

The difficulty managing that is the primary reason that most HF verticals are not installed on towers.

WB2WIK/6
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K9KJM
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Posts: 2415




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« Reply #6 on: November 28, 2007, 01:18:41 AM »

The Icom 718 is a great starter HF radio.

Even cheaper is a good used Icom IC-735 (Seen frequently right here on the Eham Classifieds) for around the 300 dollar range if you want to consider used. (I have had very good luck dealing directly with other hams through ads on Eham and QRZ. I would avoid buying on a place like Ebay.......  Even though a person can sometimes get a decent deal, That is where the deep water is and where the sharks swim!)
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KC9LXW
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Posts: 25




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« Reply #7 on: November 28, 2007, 04:20:27 AM »

Ok thanks for you replies, but now on the radials how do you mount them directly to the antenna?  I don't no how I'm going to place the anteena to the tower.  Also how long and how many of those radials do you have to place?  Do you have to place them for each band or what or just at the base of the antenna?
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AB8XA
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Posts: 30




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« Reply #8 on: November 28, 2007, 04:24:03 AM »

A quarter-wave vertical like the HyGain you mention, or my Hustler 6BTV, is only half an antenna.  It connects to the coax center conductor at what is called the feedpoint.  

To complete the circuit, and to create an image of the other half of the antenna, a ground plane is connected to the coax shield also at (very close to) the feedpoint. With a ground-mounted vertical, the earth performs that function, but not very well at all in most places.  That's the reason for radials, and on/in soil, their length isn't critical, so long as there are a sufficient number of them and they go out far enough to capture enough current to return to the coax shield.

When you put the base of a vertical up in the air, on top of an old TV mast in your case, you need to run radials outward from the feedpoint.  But unlike on the soil, these are up in the air, so they themselves must be quarter-wave antennas to capture current at that frequency and return it to the shield.  Hence, they must be a tuned length and there must be a sufficient number of them.  
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N0RZT
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Posts: 104




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« Reply #9 on: November 28, 2007, 06:47:22 AM »

Here's a couple of photos showing how I connected my radials to my antenna:
http://home.woh.rr.com/cbohn/chris/antenna/newRadials-close.jpg
http://home.woh.rr.com/cbohn/chris/antenna/newRadials-far.jpg
The thick gray cable is the feedline.  The center conductor (wrapped in tape in the photo) connects directly to the antenna.  The outer braid (the shiny copper in the photo) connects to the mounting.  The radials are then connected to the mounting.  (If you go with a ground-mount option, also note the call-before-you-dig markings!)

For elevated radials, they need to be cut to a resonant length (here's a formula you'll need to learn for the General test):  quarter-wave-length-in-feet = 234 / frequency-in-MHz.  The absolute minimum is one radial per band, but two per band would be smarter.  Conventional wisdom seems to be that four per band is about right.  For ground mounting, cutting radials to a resonant length is unimportant.

73,
Chris
N0RZT/8
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KC9LXW
Member

Posts: 25




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« Reply #10 on: December 01, 2007, 02:01:07 PM »

OK thanks alot so I actually attach the radials at the base of the antenna, but now do I have to place them for each band or just at the base or the antenna?  Ok I'm almost for certain I need lightning rods about how long and how many do I need to place?
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K9KJM
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Posts: 2415




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« Reply #11 on: December 01, 2007, 11:41:28 PM »

By "Lightning rods" do you mean ground rods?

Heavy copperclad ground rods of 1/2 inch or 5/8 inch diameter are available at most all home improvement stores for around 10 bucks each. In normal soil space them about twice the distance apart as the depth.
(8 foot deep rods should be spaced about 16 or so feet apart)
Even more important than the ground rods is properly BONDING all ground systems together, And using a "single Point" ground where all your coax enters the building.

For some good info see: http://members.cox.net/pc-usa/station/ground0.htm
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KI4FZY
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Posts: 28




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« Reply #12 on: January 14, 2008, 03:15:28 PM »

Congrats on becoming a ham!! I am 16 years old and i have been in this hobby since age 12.

You were talking about a way to attach radials to a vertical antenna. I have a homebrew bracket that is designed for that use. If you want it then send me an email and i will send it to you. No cost, just tell me it you want it. I have a many of them.  My email is jmcdiv@msn.com .

It is a ring that can be attached to the bottom of the vertical and it has wholes drilled in it for radials. I used it on a 30m vertical with 60 radials and it did a great job. It has a barrel connecter for the coax feed line.

You hook it up like this. Set up the vertical on top of you tower, then run coax from the antenna to ground level, then plug the one end of the coax feedline to the barrell connector. Take the other coax line from your transmitter and connect it to the free end of the barrell connector. Attach your radials to the ring with bolts.

There are some commercial ones made that can hold 120 radials. Here is a website with pictures: http://www.dxengineering.com/Products.asp?ID=47&SecID=16&DeptID=8

I have used vertical antennas with good success in DX contests. They do need a decent radial system. GL and hope to meet you on the air sometime!

73,
James NN4JM
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