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Post by Night Ranger on Aug 17, 2011 17:30:27 GMT -5
I've been thinking about building a screen reflector for my Lazy H antennas to get an additional 3db of gain and make them uni-directional instead of bi-directional. The problem is cost of materials. A properly sized screen reflector for the Lazy H antenna on 27 MHz is going to be about 72 feet wide and about 72 feet tall. I could use a tuned parasitic reflector and save materials, but I would lose the multi-band gain advantage of the Lazy H antenna with a full sized screen reflector.
The screen reflector could be made of mesh wire like metal chicken wire or individual horizontal wires spaced less than 0.1 wavelength apart. I've been thinking of all the sources of cheap metal to make the screen reflector out of. On the absurd side a giant curtain of old computer CD's would actually work as CD's contain a solid layer of aluminum. Maybe I could call AOL and tell them I have a few thousand people who want to sign up. I'm joking of course.
Then it hit me. There are several hundred acres of woods out behind the house. While exploring the woods I saw pieces of an ancient barbed wire fence running through the woods. The fence is so old most of the post have rotted and fallen down. Some post have completely rotted to dust. Most of the barbed wire is buried just below the surface with roots, leaves, and dirt all over it. The fence also contains one strand of razor wire which is thicker than the barbed wire, and it is in better shape. I started pulling the old rusted barbed wire up out of the dirt. Who ever built this fence is probably long dead and gone. I'm not sure how many acres this ancient barbed wire fence covered, but I may have just found the cheap source of metal for my 27 MHz screen reflector.
On another note, I was using my west facing Lazy H on 38 LSB last night. A station in Maui, Hawaii broke me (World Radio Triple Zero) and said I sounded like a local. I'm in South Carolina. Not bad for a cheap home made wire antenna.
Night Ranger
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Post by spitfire441 on Aug 17, 2011 18:22:16 GMT -5
I have a 2500' spool of aluminum wire from Tractor Supply for around $25. That is going to make my Lazy H and a dual rhombic for 40m up. Nice on your contact with a wire, i love wire antennas. BTW you were S9 sunday night, for less than 5 minutes. Glad to hear from you though. Need to get the 40m thing rolling....winter is coming, I'll hgave more time.  |
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Post by Night Ranger on Aug 17, 2011 19:43:58 GMT -5
I have a 2500' spool of aluminum wire from Tractor Supply for around $25. That is going to make my Lazy H and a dual rhombic for 40m up. Nice on your contact with a wire, i love wire antennas. BTW you were S9 sunday night, for less than 5 minutes. Glad to hear from you though. Need to get the 40m thing rolling....winter is coming, I'll hgave more time. I did not think about electric fence wiring, and it is cheap!. I'll buy a 1/2 mile roll and make the screen reflector with that. Thanks! Last Sunday I heard you come back and then the DX path between us closed. Poof! Gone! Not even a whisper after that. Oh well. |
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Post by spitfire441 on Aug 18, 2011 5:49:56 GMT -5
I have a 2500' spool of aluminum wire from Tractor Supply for around $25. That is going to make my Lazy H and a dual rhombic for 40m up. Nice on your contact with a wire, i love wire antennas. BTW you were S9 sunday night, for less than 5 minutes. Glad to hear from you though. Need to get the 40m thing rolling....winter is coming, I'll hgave more time. I did not think about electric fence wiring, and it is cheap!. I'll buy a 1/2 mile roll and make the screen reflector with that. Thanks! Last Sunday I heard you come back and then the DX path between us closed. Poof! Gone! Not even a whisper after that. Oh well. Sometimes the answer is right in front of you. Thats what I love about radio guys, pull on each other for ideas and we are good at doing it on the cheap! |
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Post by Night Ranger on Aug 18, 2011 12:24:26 GMT -5
I did not think about electric fence wiring, and it is cheap!. I'll buy a 1/2 mile roll and make the screen reflector with that. Thanks! Last Sunday I heard you come back and then the DX path between us closed. Poof! Gone! Not even a whisper after that. Oh well. Sometimes the answer is right in front of you. Thats what I love about radio guys, pull on each other for ideas and we are good at doing it on the cheap! I searched Tractor Supply's web page and it turns out they have one in my area, so I paid them a visit. I walked away with a 1/2 mile roll of 17 gauge galvanized steel wire. It was cheaper than the aluminum, but probably harder to cut. In any case I'll find out how many 27 MHz screen reflectors consisting of only horizontal wires I can make out of a single roll. I'll start with the west facing Lazy H first, since it does not make much sense to send half of my RF out over the Atlantic ocean. I have had the occasional contact in Bermuda, but not enough to waste half my RF output on. Most of my U.S. F layer skip on 11 meters comes from west of South Carolina. I also need to move my west facing Lazy H back in to the woods as it is currently picking up too much static from the power lines in front of the house. Once I get that working I'll probably put a screen reflector behind the Lazy H facing up the East Coast towards Pennsylvania. Additional nice features of a 27 MHz Lazy H with a screen reflector is it has forward gain over a single mono-band dipole all the way down to 14 MHz. Also the gain goes up as I move towards 10 meters. On last plus is you can put a second Lazy H on the opposite side of a single screen reflector and make the direction switchable. Some of the shortwave broadcast stations do that. Night Ranger |
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Post by Tombstone (R.I.P.) on Aug 22, 2011 14:41:42 GMT -5
The lazy H sounds like a wicked antenna although I'm not that familiar with them. The screen reflector should help a lot, I hope that it works out well for you. I'm still off the air since the lightening strike and I'm still collecting parts before I arrange for a bucket truck to put me on the roof. The coax change will be a problem since I have most of it on the ceiling inside and since I installed it a suspended ceiling was put up. I picked up a used A99 but have to buy a ground plane kit for it. I have a 1 to 1 balun that will mount as close to the feed point of the antenna as possible. I'm not a fan of stick type of antennas but I'm mountened on a chimney and I don't want to put anything heavier up and damage the chimney when high winds hit. I was considering using the original coax if it checks out that it isn't shorted. Does anyone have any input on that? The aluminum ground wire burnt off like it wasn't even there, so I'm going to make a ground line out of three conductor romex house wiring. I'll twist all three conductors together at each end. That should give me a heavy ground. Just my input, I'd like to use a lazy H but I rent here and I'm lucky that they let me have an antenna at all. Considering my low location right at the Ohio river, I get out well and recieve well with the A99.
Tombstone
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Sandbagger
Administrator/The Boss 
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Post by Sandbagger on Aug 22, 2011 19:42:57 GMT -5
The lazy H sounds like a wicked antenna although I'm not that familiar with them. The screen reflector should help a lot, I hope that it works out well for you. I'm still off the air since the lightening strike and I'm still collecting parts before I arrange for a bucket truck to put me on the roof. The coax change will be a problem since I have most of it on the ceiling inside and since I installed it a suspended ceiling was put up. I picked up a used A99 but have to buy a ground plane kit for it. I have a 1 to 1 balun that will mount as close to the feed point of the antenna as possible. I'm not a fan of stick type of antennas but I'm mountened on a chimney and I don't want to put anything heavier up and damage the chimney when high winds hit. I was considering using the original coax if it checks out that it isn't shorted. Does anyone have any input on that? The aluminum ground wire burnt off like it wasn't even there, so I'm going to make a ground line out of three conductor romex house wiring. I'll twist all three conductors together at each end. That should give me a heavy ground. Just my input, I'd like to use a lazy H but I rent here and I'm lucky that they let me have an antenna at all. Considering my low location right at the Ohio river, I get out well and recieve well with the A99. Tombstone If you can, consider upgrading the antenna to an IMAX-2000. It's still a stick antenna, but it works noticably better than the A99. Also, don't skimp on the gauge of the ground wire. Last week our 6 meter/220 Mhz repeater was hit with a direct strike. It pretty much destroyed the colinear 220 antenna (but it still works as a 1/2 wave), and killed a voltage regulator in the 220 repeater. But the 6 meter repeater survived intact, with the only other damage being a line voltage monitor. The antenna tower was grounded by a ground rod, connected by a copper braid strap. The massive current flow through that ground strap heated it up so much that the braid melted and fused into a solid copper strap. But it held so most of the lighning flowed into the ground via the ground strap. Had it failed, the current would have found other paths to ground and would have likely fried more equipment in the process. So whatever you use for your ground lead needs to be able to handle the current. And the longer the ground wire, the heavier it needs to be. |
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Post by Tombstone (R.I.P.) on Aug 22, 2011 23:27:21 GMT -5
Thanks for the info, Sandbagger. My ground wire had melted places in it but it burned off at the rod in the ground, so it seems to have taken a lot of current. If the coax isn't shorted, what do you think of still using it? As far as the Imax antenna, I've heard a lot of complaints that they break in high winds. I know that they work better than the A99.
Tombstone
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Post by Night Ranger on Aug 23, 2011 8:02:34 GMT -5
Thanks for the info, Sandbagger. My ground wire had melted places in it but it burned off at the rod in the ground, so it seems to have taken a lot of current. If the coax isn't shorted, what do you think of still using it? As far as the Imax antenna, I've heard a lot of complaints that they break in high winds. I know that they work better than the A99. Tombstone I have owned two Max-2000 antennas. They were both in the top of 70 foot plus tall pine trees. The first one lasted from 2003 until 2009, and then the strong March winds we get every year in South Carolina snapped it. The second Max-2000 exploded in 2010 after a lightning bolt hit it. Performance wise the Max-2000 worked well, but my old aluminum .64 wave Radio Shack ground plane was probably the best. I have tried to use coax that took a lightning strike in the past. It still worked, but the SWR was higher after the strike even with a new antenna at the other end. I imagine the line loss per foot was higher as well. For skip talking the Lazy H is probably the best out of all the antennas I have tried. Below is a list of various base antennas I have used over the years; 1) Radio Shack 5/8ths wave aluminum ground plane - Good antenna 2) Radio Shack 1/2 wave big stick - Fair 3) Radio Shack .64 wave aluminum ground plane - Great antenna - 500 watts PEP max 4) Vertical 1/2 wave dipole hung from a high tree limb - Not bad, but not great 5) Horizontal 1/2 wave dipole - Great for nulling out sources of interference like jammers or power line static 6) Horizontal extended double zepp - Works well for skip. Good rejection off the sides 7) Horizontal full wave tall rectangle shaped loop/quad - Good skip antenna. Very little rejection off the sides 8) Vertical full wave tall rectangle shaped loop/quad - Kicks butt if given some height above ground 10) Vertical 3 element Yagi beam - Great for DX and local 11) Horizontal Lazy H antenna - Excellent skip antenna. The best skip antenna I have used so far. 12) Solarcon Max-2000 - Good local antenna and long range DX antenna. At 75 feet up at the base of the antenna it worked skip stations at 1500 miles plus very well, but seemed to put in a weaker signal to skip station less than 1000 miles. Night Ranger |
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Post by homerbb on Aug 23, 2011 8:08:24 GMT -5
About the coax I'd say test it and see, however, there is a stubborn old fellow about 20 mikes out from me who also suffered a lightning strike which took out his radio. He replaced the radio, but he insisted his coax checked out, and his SWR is good. He continues to use the coax, but is barely perceptible on my receive, and to others also. If there is any white noise I can not tell what he's saying. Before the lightning strike that was not the case.
I know a meter and SWR are good indicators of coax condition, but performance will tell a fuller story. You may do alright with the current coax, or not.
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Post by cbrown on Aug 23, 2011 9:14:54 GMT -5
Forget the GP kit on the A99; they really don't do anything and since you plan on putting a 1:1 balun on the antenna anyway, you'll save some $.
As for the coax, you can test it to check it. When I took a strike on my system, I thought about just replcing the radio as the antenna and coax look to be untouched. My elmer at the time actually told me to replace everything, since I couldn't be 100% sure what paths the lightning took when it hit.
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Post by Tombstone (R.I.P.) on Aug 23, 2011 14:58:31 GMT -5
Yeah, you're right. I know better than to use the old coax.
Tombstone
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Post by Night Ranger on Sept 9, 2011 12:20:56 GMT -5
This weeks Classic Radio Roundup proved the need for me to go ahead and put a screen reflector on my Lazy H facing towards Pennsylvania. The skip was coming in really strong from Mexico, Central and South America, and the Caribbean on Wednesday evening. All I could hear was strong Hispanic speaking stations and the roar of countless AM carriers.
After the F layer skip fell out I could hear much weaker sporadic E skip coming from the Great Lake states. I never did hear anyone in Pennsylvania, but I was hearing Indiana, Michigan, and Wisconsin. With the increasing solar flux the signals coming from stations south of the U.S. will be more of an interference source for me. A full sized screen reflector has substantial rejection, and the south end of my Lazy H facing Pennsylvania is aimed right at Central America and southern Mexico.
Night Ranger
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Sandbagger
Administrator/The Boss
Posts: 6,250
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Post by Sandbagger on Sept 9, 2011 15:03:29 GMT -5
This weeks Classic Radio Roundup proved the need for me to go ahead and put a screen reflector on my Lazy H facing towards Pennsylvania. The skip was coming in really strong from Mexico, Central and South America, and the Caribbean on Wednesday evening. All I could hear was strong Hispanic speaking stations and the roar of countless AM carriers. After the F layer skip fell out I could hear much weaker sporadic E skip coming from the Great Lake states. I never did hear anyone in Pennsylvania, but I was hearing Indiana, Michigan, and Wisconsin. With the increasing solar flux the signals coming from stations south of the U.S. will be more of an interference source for me. A full sized screen reflector has substantial rejection, and the south end of my Lazy H facing Pennsylvania is aimed right at Central America and southern Mexico. Night Ranger Yea, we hoped the conditions would be favorable for you to get in there agin Wednesday night. We had a little bit of skip, but it was not all that great. We were also caught in a deluge of rain all day Wednesday which flooded a lot of local areas (even more so than Irene did a week prior), so the presence of the storm may have blocked the E-layer stuff to us during the roundup, as it was mostly a laid-back-local affair. |
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