Date: Mon, 19 Jul 1993 10:58:24 -0500 (CDT) From: "Jeff M. Gold" Subject: LB Quad review To: qrp@Think.COM Message-Id: <01H0Q2ZIYWR6AH2S9U@tntech.edu> X-Vms-To: IN%"qrp@think.com" X-Vms-Cc: JMG Mime-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=US-ASCII Content-Transfer-Encoding: 7BIT OK, Here is the review I promised: Lightning Strikes Review of the Lightning Bolt 5 band, 2 element cubical quad: Gain: 8db F. to B. 26 Side Lobe 50 Boom diam. 2" Turning radius 10.6' Weight 25lbs Arm Length 13"4" Actual SWR measure after installation using given assembly measurements: 10 Meters: 28.000 2.0:1 28.200 1.7:1 28.300 1.5:1 28.500 1.12:1 28.700 1:1 29.000 1.2:1 29.700 1.6:1 12 Meters: 1.5:1 or better 15 Meters better than 1.4:1 17 Meters 1.5: or better 20 Meters: 14.000 1:1 14.100 better than 1.2:1 14.350 1.2:1 * I just did what the instructions said and did no tuning (yet) ---------------------------------------------------------------------- The Saga Begins: I really wanted a directional antenna. All the work involved scared me. I saved for a while and went to the big Hamfest in Huntsville, Al. This was my first big ham fest. I had enough money to buy a two element 3 band Yagi. I would then save for the tower and the rotor. I went to the hamfest and hung around the antenna booths asking a lot of questions. I came across the Gap booth and there seemed to be a bunch of people who had previously purchased a Gap Vertical and were very happy with their purchase. My elmer has been using the Gap with very good results for a long time. I ended up spending my money on a Gap. The Gap was very easy to assemble and put up and I have used it for two years. I really love QRP and was getting the directional antenna bug again. A friend has a quad and I think they are really nice looking and have heard him up against a local Mosley tri-bander chasing DX. The quad seemed to get through a lot better. About a year ago I sent for the literature on the Lightning Bolt five band two element quad. I read a lot about the pros and cons of quads versus yagis and decided on a quad. The work involved and the cost kept me back. Progress A friend offered me 30 foot of tower that matched 30 foot of tower that held my TV antenna, this was the first sign that I needed to take some action. The second sign was that my TV antenna was about dead. The third sign was the article in CQ magazine saying the Lightning Bolt really worked well. I took the old TV antenna down from the tower and mounted a new one on my roof attached to the chimney. Had loads of fun with wrong parts and such. This freed up my tower. The only problem was that I had very large trees all around the tower. I got out my chain saw and tuned it up. I ended up having to take down seven trees that were all 70 foot or bigger. Luckily a new ham friend happened by with his pickup and helped out. Instead of cutting up the trees, we hooked them to the truck and pulled them into some acreage I don't use. I then had to pull the top of the tower off and added an extra 10 foot section and put the top section back on . This turned into quite a project. This was bested by putting up of the 21 foot section of thick walled steel pipe. I think anyone who puts up a tower needs to find a friend with a Cherry Picker. Without any special devices except for a climbing belt and rope, we managed to drop the mast down through the middle and back thru the appropriate support. Building the Antenna All of this was taking place over a month and a half period. My antenna had arrived about three weeks after cutting down the trees. The intsructions were only a few pages long. There was only one unclear part in all the instructions. This involved the tuning stubs for the reflector element. There is a section that describes an eight inch variable stub and then the next section gives exact measurements for the stubs for each of the 5 bands. I chose to use the specified measurements and didn't figure I wanted to mess with this antenna if in fact I ever got it all assembled. I took my time building it. I assembled the spider parts one night then built the reflector then the driven element. You only need to be careful with the wire. It likes to coil back up and could really get you hurt if you let go of it. We were pretty carefull cutting the wire which was a little hard because of the type of wire, but nothing to worry about. It is really pretty easy to put together and very light. Finished Well we finally got everything built and I wanted to see the antenna work. The temperature was about 99 degrees and much hotter on the roof. It took about 5 hours in the hot sun getting the elements on the boom and the rotor working right. I went into the house very nervously. I took out my MFJ digital antenna analyzer and hooked it to the antenna. I let out a big sigh of relief and went outside yelling and screaming. My friend who was helping me was still strapped to the top of my tower and was very relieved to hear the good news. On the Air We were both pretty heat sick at this point, and drenched. I turned on the radio and actually plugged in a microphone, something I hadn't done in a while. I worked VP5M in the Caicos Isands on 15 meters, then I8UDM first call thru a pileup on 17 meters, CT1GG/CU3 first call to the Azores on 17 meters. I hooked up an antenna switch and went back and forth between my Gap and the Quad. the Gap would read 51 and the quad would read 57 to 59. In some cases I couldn't even hear the station on the Gap and he would be nice and strong on the quad. The Real Test WS4S, the only other QRPer in town came over the same evening to help work on a friend's tube rig. He had to play with the new antenna before we started on the rig. The first thing he did was turn the power on the rig down to 1 watt and worked 4X1EL, after which I worked him also. He was grinning and getting ready for some serious experimenting. He turned the power down to 20 MW and wokred Z36CXN in Macedonia. I really wanted the same station, so I cheated and cranked the power all the way up to 70MW. Next he said. "this will be futile, but I am going to call CQ." He turned the power to 50 mw and called CQ once. He said, "this is futile." I said, "you better stop talking about QRP that way, try again." He called one more time and YO8CDC came back to him. He talked to this guy on 20 meters and turned the power down to 10mw. The RST was 549. Next he worked HA5HC in Hungary. He started with 50mw and the RST was 579. He started chatting and turned the power dwon to 10mw. The RST was now still 579 and Emil reported the signal was nice and strong. Next he turned the power to 1mw and the RST went all the way down to 559 with a good report. Conard, WS4S talked with Emil for quite some time on LOW POWER. Guess Well my feeling is the antenna is working ok and that I got my money's worth. As I keep saying, "you shouldn't have low expectations on performance just because you are using low power." 72 Jeff, AC4HF ====================================================================== Date: Mon, 19 Jul 93 22:52:07 PDT From: dh@deneb.csustan.edu (Doug Hendricks) Message-Id: <9307200552.AA12846@deneb.csustan.edu> To: qrp@Think.COM Subject: Hamstick Mobile Antennas I read Chuck's account of going mobile CW, and Jeff's antenna review, so I just had to tell you about my Great Antenna Adventure. August 2nd I will be mobile on 20 and 40 cw as I make the trip to Kansas to visit my father. I am traveling alone, so if you hear me calling cq, answer. Ok, guys, here comes my adventure with an antenna. About a month ago I was inspired to take my rig with me when I make my trek across the US to visit my father in Kansas. So, I needed a mobile antenna. I purchased the hamstick model from Lakeview Co., Inc. 3620-9A Whitehall Rd., Anderson, SC., 803-226-6990. I bought the 20 and 40 meter resonators and the triangle mag mount. Came to about $75. About a week or 10 days went by and one day the Big Brown Goodie Truck stopped by and delivered my antennas. Wow was I excited. I immediately opened up the 40 meter resonator, read the instructions, albeit not too well as you shall see. I quote: "Note: The Exposed whip lengths shown are approximate. Actual lengths will depend on several factors including mounting position, coax length, other antennas in the area and matching method. Again do not allow the whip to enter the close wound loading coil area of H.F. antennas." This was the paragraph that led me astray. Ah hah, they don't want any whip in the coil part, ok....so I looked at the suggested length chart for the 40 meter band....let's see if I want it resonant at 7.000, it needs to be about 40" long. Hmmn, usually they are off a little....the total length is 47" so I will cut 5" off. That was going to give me 2" extra. So, I went to the shop, got out the hack saw and cut off 5" of the whip. BIG BIG MISTAKE. Notice that I did not hook it up to the rig and check the SWR, nooooo, not KI6DS, he is too "smart" for that! After I cut off the whip, I put it in the resonator, tightened the screws and mounted the antenna. Tuned the rig to 7.005 and checked the SWR. OH MY GOD!!! It was about 5 to 1. Whoops, started up the band, tuned farther and farther, the top edge of the CW portion coming up, let's see, darn, SWR still out of sight. I'm beginning to realize at this point that I have done something terribly wrong. I am hoping that the antenna will at least be resonant in the SSB portion, no way, as I approach 7.3 I find out that the antenna has an SWR of 3.5 to 1, entirely unacceptable. When I finally found the resonant frequency, it was at 7.445, not really a great spot for mobile cw work. I called the company. Butch was really nice, told me that yes I had screwed up by cutting the whip, but not to feel too badly, I wasn't the first to do so......that made me feel really great. I asked and was told that another whip would be $6...so I ordered one. Now those of you who are astute will be saying "why didn't he use the other whip from the 20 meter antenna?" Not to be, my friends, as you see Dougie, the antenna wizard of the west, had also trimmed the 20 meter whip at the same time as he was trimming the 40 meter. It was even worse, as I cut 7" off the 20 meter whip. Why did I do that? Dumb I guess, I don't know. (You aren't the first to ask, my wife beat you to it!) Shoot, I had the hacksaw in hand, one whip was cut, might as well get the other one done while I was at it....... What was the fix? Ok, here is the solution that I found. I got a piece of 1/4" round stainless steel rod, cut it 2 inches long, put it in my milling machine and faced off both ends square. I then drilled an 1/8" hole in each end about 3/4" deep. Then I drilled and tapped a hole for a 4-40 screw about 1/4" from each end to hold a set screw. Put the end of the whip in one end, the cut off end in the other, and instant connector. Works like a charm. Doesn't look too good, but I tell all of my friends that it is a "special thig-a-ma-jig that goes on this antenna". They look at it, shake their heads and mumble about "antenna's are weird" as they look at the SWR meter that is reading 1.1 to 1. How does the antenna work? First contact was with a Salt Lake City station. He gave me a 579, I was using 2 watts. He was a 599, but he was running 100 Watts to a dipole up 60 feet. Second contact was on 20 meters. Yes, I had to make "two of those special connectors", but at least I have a matched pair! Har Har. The second contact was SSB, using 2 watts. Talked to a guy on a sail boat about a 100 miles off the coast of Mexico. He was flabbergasted when I told him I was running 2 watts in to a mobile antenna. Hamsticks are good antennas. They are cheap, about $18 per band, the mag mount that I bought cost $35, but it holds the antenna with no problem going 75 mph down the freeway. I recommend them. They get out, they are easy to tune (but for heaven's sake don't trim the antenna whip until you check the SWR first). If you have questions or brick bats, send them to me hear on Internet. 72, Doug ====================================================================== Date: Mon, 28 Jun 1993 10:15:02 -0500 (CDT) From: "Jeff M. Gold" Subject: Great wire antenna To: qrp@Think.COM Message-Id: <01GZWPCXG1SO9JD4CS@tntech.edu> Hi, A good while back I pulled some info about the ZS6BKV antenna from somewhere. I built one for Field Day. This is a 5 band tunerless antenna which was developed using computer modeling. It has a good SWR on 40, 20, 17, 12, and part of 10 meteres. Mine also was resonant at the lower end of 80 and worked fine on 15 meters. It is 92 feet 2 inches of wire (split in half as a dipole) with 40 ft of 450 ohm ladder-line as a matching section. This is then directly connected to some 50 ohm coax.. I used RG58/U. I then took about 5 extra feet of coax and tightly looped it around the end of the coax section nearest the 259 connector to keep out RF. The club used a 440 with an autotuner and a bunch of QRP kits I had built. The antenna was up at about 25 feet to start, then I restrung it to about 40 feet. The 440 easily tuned the antenna on all except 160 meters (no big surprise here). The antenna worked GREAT. After I restrung it at the 40 foot height.. seemed to be able to work everyone first try with the 100 watts and had real good success with the QRP rigs. The antenna seemed to outperform the G5RVs that were strung around at the other tents.. and has the advantage of working a number of bands without a tuner 73 Jeff,AC4HF ====================================================================== Date: 14 Apr 1993 17:15:43 -0500 (CDT) From: "Jeff M. Gold" Subject: Portable vertical To: qrp@Think.COM Message-Id: <01GX0BNEBYDKIB9SQ4@tntech.edu> X-Vms-To: IN%"qrp@think.com" X-Vms-Cc: JMG Mime-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=US-ASCII Content-Transfer-Encoding: 7BIT Hi, being senile, don't remember whether I posted this.. so lets do it again ( I am currently teaching an intro to computers course.. they are all doing a spreadsheet project.. taught them so well..only need to be in the room to answer an ocassional question. Well CQ a while back had an article about a 1/4 vertical made very inexpensively from PVC. I made one and it worked good and so I made a 1/2 wave to see what the difference would be.. worked a lot better.. very broad banded and surprisingly with only 2 radials..really gets the signal out (see Feb 93 QST). These are helically wound. Well been testing both the new MFJ 20 and 40 out and wanted to take them both portable (they both will easily fit in the bottom of my backpack). I have the bottom section of my original 20 meter with 2- 40 meter length radials. I then wound the rest of the needed length to make the equivelent of a 40 meter 1/2 half wave (about 3/4 of the total needed coiling on the top section.. so I wouldn't have to mess up the 20 meter part). First try no reasonable SWR..pigtailed another length of wire.. got a little closer..put one more lenght then cut off a section.. never even soldered them.. didn't space out the windings.. and just used electrical tape to kinda keep things in place while I was playing around. Using the MFJ digital antenna analyzer makes these things easy for me to experiment with. Well I noticed the only difference the coiling seemed to make was to effect the electrical length of the antenna.. thus changing the SWR. Got the SWR down to about 1.3:1.. put a whole mess of tape around the mess I had created and it was just starting to get dark. I ran in the house and got the 2- MFJ rigs and a Gell Cell. The antenna really seemed to be receiving well from my driveway.. Heard someone calling CQ.. gave him a call and he came right back. Think he was a 579 with 100 watts on a Kenwood 450 and some kinda permanent antenna. Think that wasn't bad for 4 watts and some plastic pipe. I took the 20 meter top and replaced it and checked the SWR.. was still perfect.. So I can use the antenna on 2 bands with the same 40 meter radials and just replace the top section. I am next going to see if I can use my small tuner to tune it on someother bands... I am going to come up with a very small light weight multiband portable antenna that will go well with backpacking (day packing that is.. I like to climb mountains in the smokies and set up.. may start using my HW9). 73s Jeff, AC4HF ====================================================================== To: David Adams Cc: qrp@Think.COM Subject: Re: Portable vertical In-Reply-To: Your message of "Thu, 15 Apr 1993 10:19:19 CDT." <9304151519.AA24447@cherry10.cray.com> Date: Thu, 15 Apr 1993 09:17:04 -0700 From: Clark Savage Turner WA3JPG Message-Id: <9304150917.aa05815@Paris.ics.uci.edu> I would echo Jim's comment about "plain ol'" wire antennas for the backpacking at heart. (Not that I don't appreciate the helically wound vertical.....honest!) You can get a 65 foot dipole wound up pretty tight, light and neatly into your pack, along with twin lead if you desire. You can wind back the ends (physically and electrically shorten the antenna.... as in short the physical end of the antenna to the shorter end you desire at, say 16 feet from the center) and have the dipole of your choice. As for me, I have backpacked along the Appalachians with an Argonaut (509) and its matching little tuner. I use a piece of thin wire about 100 feet long and throw it up into a tree in any fashion feasible, then back up to run out the wire as long as is comfortable. I connect the end to the tuner, and I can get on all bands. If I am located well, I do darned respectably on 40 SSB (my favorite place to go QRP lately). I usually carry "D" cells for power, the power to weight ratio is better than gel cells it seems....and I am already pretty loaded just carrying the Argo monster. But I have a heck of a lot of fun. I have also used verticals, but usually wires with fishing line attached and slung over a branch to give me the active quarter wave vertical part, then a couple of random wires on the ground for radials. Seems to work well on the higher bands when I have a fairly low angle to the horizon, but my verticals on the 40 meter band have been to difficult and just unpredictable (75 is probably worse, never tried a wire vertical there....), so the 100 foot wire goes up. Heck, a 100 foot wire is just about all I ever use, even at home! 72 Clark ====================================================================== From: Kevin Purcell (Rho) To: qrp@Think.COM Date: Wed, 2 Jun 93 08:41:32 PDT Subject: The Half Square: A 2 element Bobtail Curtain. Cc: mvjf@mvubr.att.com Jim - W1FMR, mvjf@mvubr.att.com says: I have used one with much success. It was not fed at the top, but at the bottom of 1 element. 1/2 wave _________________ | | 1/4 wv.| | 1/4wave ^ ......Matching circuit to rig here. ####### < Ground screen. It was a non-resonant antenna, tuned with a parallel LC network connected between 1 element of the antenna, and the ground screen (a 3X5' piece of hardware cloth or screen). I say: It certainly is a resonant antenna (it's 1 wavelength long) but you are feeding it at a high Z point hence the parallel LC circuit. Feeding it in the corner seems easier (and does away with the screen). The reasons why this antenna is better than a few others is: 1: the radiating elements are vertical, leading to a lower angle of radio than a dipole at the same height. The horizontal currents in the 1/2 wave "top" section cancel (in first approximation) eliminating radiation upward. Hence its a good DX antenna but a poor "local" antenna. 2. Either the voltage feed or the current feed result in the high currents being at the top of the radiator (unlike a regular bottom fed quarterwave where the current is close to the ground. 3. No ground losses (even with the voltage feed the currents are low in the screen so the losses here are low). 4. You get some gain (and directionality of course) from feeding two phased vertical quarter waves (but not much). There was also a writeup in CQ in the last few months about this antenna -- a few plots of its calculated performance were shown plus details of how to build one (a two band version I think?). Final question which I havent set in my mind yet: is this a balanced antenna? I think it is (think about the currents around the feed point) and should be fed with a balun. But non or the corner fed designs actually do this. It might make a difference if your coasx is horizontal for some distance radiating and picking up high angle waves. This would degrade its prference for low angle signals. As an aside I have seen the Zuni Looper's use Sterba curtain's on 20m at some high to get killer QRP signals. A good idea for field day. Kevin Purcell N7WIM / G8UDP a-kevinp@microsoft.com "We conjure the spirits of the computer with our spells"