Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: New ham getting on HF frustations.  (Read 3886 times)
K7PRT
Member

Posts: 6




Ignore
« on: August 02, 2008, 04:00:12 PM »

I'm working on getting my hf rig up and going and am getting absolutely frustrated in that I don't know right from wrong.  All I get is fuzzy answers and I'm at a loss.  Hopefully you guys can give me some concrete answers so I feel better with going ahead.

The setup:
IC 735 running to a tuner, 300ohm twin lead heading around the house to the back yard connected to a 40m dipole strung 20 feet up.  Wife hates the legs of the dipole that've taken over the back yard.

Have a loaned av-5 with a tripod, looking at bolting the tripod down to the rear deck which is about 3ft above ground level.

Grounding:
I'm lost, I was told I needed a ground rod just outside my shack 8' down.  I have a copper water pipe in the room but I don't want to use it cause it'll bring RF into the equipment.

Radials for the vert:
Told to run wire around the house between the radials I'm supposed to run at the base of the av-5 and the rod i'm to put in out front.  I've heard to bury the radials, don't bury them.  Don't use them as they'll be several feet below the vert.  Run a line from the radials up to the vert and bind it to the tripod.

I'm so flustered I haven't a clue what I'm doing.
Logged
N4KZ
Member

Posts: 605




Ignore
« Reply #1 on: August 02, 2008, 05:16:20 PM »

There are two types of ground -- DC and RF.

An 8-foot rod will make a good DC ground for your equipment and should keep you from having RF get into your gear. Cold water pipe grounds are usually not sufficient for this purpose. I've tried both and much prefer the ground rod.

As for the vertical. If it's only 3 feet above the backyard, lay radials on the ground and run a wire up to the feedpoint of the vertical and attach the wire to the ground side of the feedpoint. Ground radials, which constitute RF ground for your antenna, work equally well whether they are buried or just lay on top of the ground. Again, I've done it both ways and each has its pros and cons but electrically they are the same. The only real advantage to burying them is they are out of the way and no one trips over them. Otherwise, if it's convenient, lay them on the ground. I prefer that method because it's easier.

73 and good luck,
N4KZ

Logged
W5CPT
Member

Posts: 561




Ignore
« Reply #2 on: August 02, 2008, 05:49:35 PM »

You have quite a few things going against you here. Let's try to take apart what you have.

You said>
IC 735 running to a tuner, 300ohm twin lead heading around the house to the back yard connected to a 40m dipole strung 20 feet up.

I say> The Twinlead should be suspended in the air for best operation.  I am not sure what "running around the house" means but every time Twinlead runs along side a metal structure you lose signal. The closer and farther it runs, the more you lose.  This will affect both TX & RX.  The Twinlead should come away from the dipole at a 90 degree angle or as close as you can get it. And the Twinlead should never run along the ground - same effect as running along the metal gutter.

The antenna is lower than optimal but should be good for local stuff as the pattern of an antenna that low is straight up and straight down. For more information (probably a lot more than you need), google NVIS - near vertical incident skywave.


You said>
Have a loaned av-5 with a tripod, looking at bolting the tripod down to the rear deck which is about 3ft above ground level.

I say>

Not really a good idea - see comments on radials later.

You said>
Grounding:
I'm lost, I was told I needed a ground rod just outside my shack 8' down. I have a copper water pipe in the room but I don't want to use it cause it'll bring RF into the equipment.

I say>
HUH? Yes a ground rod as close to the shack is desireable and connecting to the Power Point ground is best, the Copper Pipe should not cause RF in the equipment -- UNLESS --  There is a disconnect (insulator) somewhere between the pipe and the main METAL water pipe coming into the house.  If your water feed is PVC that would explain it.


You said>
Radials for the vert:
Told to run wire around the house between the radials I'm supposed to run at the base of the av-5 and the rod i'm to put in out front. I've heard to bury the radials, don't bury them. Don't use them as they'll be several feet below the vert. Run a line from the radials up to the vert and bind it to the tripod.

I say>
Assuming the AV-5 is some sort of Vertical the antenna it will work as designed if the radials are attached as close as possible to the base.  This means ground mounting it and running the radials out from the base.  You can elevate the mount but then you must elevate the radials (more on this later).

The "Bury them / don't bury them" discussion (started long before you got involved in it) is really a non-question.  For ground mounted Verticals, the radials couple the shield of the coax to the ground. This makes the earth the other half of your antenna.  Only one set of rules need be applied.  More & Longer is better. Size of the wire doesn't matter, insulated - uninsulated doesn't matter.  Bury them if you don't want to trip over them - leave them on top of the ground if you and your significant other don't care what your yard looks like (my situation - I am the one who mows - she likes ham radio because I am on the sun porch playing with my radios - not sitting in a bar talking to the Bar Maid)  

For elevated radials a whole new set of rules comes into play.  You can get away with only 2 or 3 (4 is better) per band. They must be cut for the frequency of interest, and should be angled away from the base at about 30 degrees (someone will correct me on this - I'm sure). And they should be as symetrical (sp?) as possible. So if your AV-5 is a 10-15-20 M multiband vertical, you could roof mount it (or stick it on a TV style mast) and run 2 radials per band (total 6)from the base.  Make sure the ends are well insulated as there can be RF hot spots there.  There is a good article on dxengineering.com under the Hustler 6BTV header by WB2WIK about elevated radials that gives a lot more detail.

While I have more than that now, that is exactly how I started.  I had a 450 ohm ladder line antenna (still have it actually in the work shop) and a Hustler 4BTV in the yard with no radials.  My ladderline was coiled up on the ground under the window and my rig was deaf and couldn't be heard across the street. I had done that because I didn't want to cut my new 100' ladder line.  My Elmer, W1ARE (sk) came over and laughed out loud when he saw it. Today Elmers are hard to come by, but I urge you to seek out your local club and find someone who is willing to help a new ham.  This forum is a fine place to get some info but a near-by ham is better.

Read the manufactures instructions as they will tell you most if not all you need to know and ask for help when you need it.  Feel free to email me directly if you get in a bind.

Hope to hear you on the air soon,

Clint - W5CPT
Logged
K7PRT
Member

Posts: 6




Ignore
« Reply #3 on: August 02, 2008, 06:45:38 PM »

That's the kind of information I was needing.  Had the local ham guy come down and give everything the once over as well.  I think the loaner is going to go back to the owner and I'll do something with my twin lead.

Thanks for the advice!
73's
Logged
WB2WIK
Member

Posts: 20666




Ignore
« Reply #4 on: August 04, 2008, 01:25:55 PM »

What's an AV-5?

Do you mean the Cushcraft MA-5V???

It really, really matters...

I wouldn't install an HF vertical on a tripod on a deck where people can potentially touch the antenna.

Far better to install it above the peak of the roof, where it will both work better and also not be touched by anyone.

If it's the MA-5V it doesn't need any radials.  But I'm really not sure what antenna you mean.

WB2WIK/6
Logged
K8JHR
Member

Posts: 29




Ignore
« Reply #5 on: August 12, 2008, 02:16:53 PM »

AV-5 Antenna might this one for 2 meters:

http://www.rami.com/gaa/antenna-info.cfm?pid=15

The AV-5 is an economical Ground Plane base station antenna. It is ideally suited for use with Unicom transceivers and is field tunable for the frequency band desired. The radial arm angle is designed to give optimum VSWR at the tuned frequency. Durably constructed of high quality materials for a long operational life, the antenna is designed to withstand windspeeds up to 100 mph.

Might be OK on a tripod, and without radials, but I would mount it up high for the reasons the other guys gave you about RF burns and better angles.

==========  K8JHR  ==========
Logged
K8GT
Member

Posts: 3




Ignore
« Reply #6 on: September 16, 2008, 08:29:28 AM »

The AV-5 is most probably the Cushcraft AV-5, a 5 band vertical for 10, 15, 20, 40, 80 and is an older, out of production model, and it requires radials.  I have an AV-3 that I use for portable operation.  Rather ruggedly built.
Logged
KB1GKN
Member

Posts: 4




Ignore
« Reply #7 on: September 23, 2008, 07:37:32 AM »

I believe that the AV-5 is indeed the Cushcraft AV-5. The manual for it is available from them at http://www.cushcraft.com/support/pdf/av3482.pdf

I used an AV-5 when I first started on HF and I was pleased with its performance. Just mounted it to a piece of pipe driven into the ground at ground level and ran radials across the lawn...

As for the IC-735, that's the rig I'm running right now. Nice radio, easy to learn and operate and just enough features to be useful but not so many that it's overwhelming. Enjoy it, it's a decent rig!

73
KB1GKN
Logged
K7PRT
Member

Posts: 6




Ignore
« Reply #8 on: September 23, 2008, 08:36:01 AM »

I've worked OH from NV with it with little trouble.  I still need to run my radials, The gain loss is pretty apparent.  It is indeed the Cushcraft AV-5, I like it so far though my wire is a bit more of a talker right now.

My only complaint with the 735 is that when the bands have a lot of QRN I have trouble pulling folks out,  I'm thinking an external AF dsp may be in order.

As for everyone that posted advice, It's helped as I'm on the air and have about 40+ QSO's under my belt.
Logged
KB1GKN
Member

Posts: 4




Ignore
« Reply #9 on: September 24, 2008, 07:24:58 AM »

K7PRT said: "My only complaint with the 735 is that when the bands have a lot of QRN I have trouble pulling folks out, I'm thinking an external AF dsp may be in order. "

 I don't have much advice to help with QRN, other than going to a higher band. Maybe set the AGC faster (button in) so the RX recovers from noise bursts quicker??? Have you tried playing around with the notch filter and PBT? I find that tweaking the PBT helps a lot in QRM situations...

 If you do try an external AF DSP, post an article with your experiences - I'd love to hear how it works! I've been considering playing around with it a bit myself; perhaps a soundcard based DSP as a starting point...
Logged
KB9CRY
Member

Posts: 4283


WWW

Ignore
« Reply #10 on: September 25, 2008, 12:21:30 PM »

Your most likely just seeing the limitations of the old 735. No amount of external DSP or ESP is gonna help.

Logged
K0RGR
Member

Posts: 106




Ignore
« Reply #11 on: October 06, 2008, 06:02:37 PM »

Unfortunately, most man-made noise in houses is vertically polarized, so verticals near houses tend to pick up a lot more noise than horizontal antennas. I've seen exceptions to this rule - but in general, verticals pick up more noise.

Generally, horizontal antennas are quieter than verticals, and loops are quieter than dipoles. But, the vertical gives you an advantage for transmitting, particularly over long distances. The vertical provides a lower angle of radiation, concentrating more of your energy at the horizon.

One answer to your problem might be to use a separate receive antenna. If your rig has a provision for a separate receive antenna, you're set. If not, you'll need to generate an external relay to switch antennas for you when you transmit. If the noise is really horrendous, more radical approaches might be needed.

Most 'noise blankers' don't do a lot of 'blanking', and DSP can help, but won't really clean up nasty grunge that much (though I find IF DSP more effective on impulse noise than audio DSP). The best blankers ever had separate receivers operating at about 40 Mhz.. They would sample the noise energy at that frequency, and invert it, then feed it back out of phase with the incoming noise, cancelling it out very well. Manufacturers started putting in simple diode clipper circuits, and calling them blankers, and we've lived with that ever since.

There are outboard commercial units that will do this. However, I'm not sure how well they work. I may get to find out in the near future - I'm moving into a new house that is 330 feet from a medium voltage power feed for the city. 40 meters and up sounds clean, but 80 is noisy.
Logged
AD7WB
Member

Posts: 33




Ignore
« Reply #12 on: December 26, 2008, 01:30:24 PM »

My IC-730 benefited greatly by the addition of a CLRdsp AF DSP now made by West Mountain Radio. And a horizontal antenna has proven much better for noise in my case. I would be very interested if someone has investigated the true E-M physics behind this. I suspect noise sources work against their local ground so an antenna that is more or less balanced to ground doesn't pick them up as well. And I can't visualize how to create a vertical antenna, even if not a monopole, that is balanced to ground. A vertical dipole really high I guess. Or a vertical dipole with a counterpoise top and bottom?

73,

Lance AD7WB
Logged
KC9MXC
Member

Posts: 25




Ignore
« Reply #13 on: January 08, 2009, 11:16:49 AM »

I know that this can be frustrating so I'm going to suggest what worked for me.  Go down to the nearest library (or bookstore or amazon or ebay...) and check out (1) The ARRL Operating Manual, (2) The Practical Antenna Book by Joe Carr.

Additionally look for info at www.arrl.org.  There's a ton of help and information to be had.  

I'd also suggest the ARRL Antenna Book as the gold standard for just about any ham related antenna issues.

Happily my XYL is very supportive and has no problem with any antenna "stuff" around or on the house.  

Good Luck!
Logged
K7PRT
Member

Posts: 6




Ignore
« Reply #14 on: January 08, 2009, 12:17:53 PM »

I'm getting along much better now.  I've got my ground setup all cleaned up, radio is happier.  I have the league OP manual and the Antenna book, plus a bunch of others I just had to have, hihi.

I've found digital to be working well for me, but I just received my nice new heil headset and so have been working phone again while I study up my code.
Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!