K7ALA - 20M Yagi

20M Yagi broken

nospam@example.com (John) — Thu, 12 Mar 2009 16:28:38 -0600

You know, I haven't been very faithful about entering stuff here. But I did want to write down that when guying the 20M make sure the ground is not soft. During the K5D escapades, I tried to use my 20M beam on soft soil (warmed by the sun after being wet all winter), and the ground gave way and my 20M fell over breaking 3 of the dowels. Of course having made this myself it was a pretty easy fix. But I also added another change which was to put wire connectors at each location the dowels attach to the boom/element supports. This makes it a lot easier to disconnect the elements for transportation and since the wire lengths are still the same (I made sure to cut everything just right so they would remain the same length), they have the same SWR. I might add photo's later, but this is probably enough.

20M Yagi completed

nospam@example.com (John) — Mon, 17 Nov 2008 22:44:59 -0700

It's always nice to get a project done and then get to test it out. Today I was able to get my 20M mini yagi finished. And I was able to test it out. My first contact was in Alberta Canada. And my 2nd contact was NE of Tokyo Japan. Wow - that was awesome. Of course I had to turn the antenna to hit these different places, but I had taken my gear out side and setup right under the antenna so it was no problem. It's Nov 17th and there is no snow and the weather was approx 45-50 deg F. I think. So sitting outside was ok with a jacket.

They were my first HF DX contacts (if Canada is not DX, then Japan was my first HF DX). And my 3rd and 4th overall HF contacts. It's sure nice when plans come together.

The bands were not too good today, and so that makes it even more amazing. I was only hoping for Hawaii, but when I heard the J callsign I wasn't sure he would be able to hear me, like maybe he was using an amp. But when I called out he heard me and gave a 5-7 signal report, and I was getting a 5-7 from him. I was using 100W, my 20M mini yagi up about 15'-18' on a buddipole tripod - I could have gone higher but that's where my guying was set for and I hate re-guying.

Yagi's really do cut down on the noise from other directions. And that was nice. But I was really surprised to get Japan. Like I said these were my 3rd&4th contacts and my 1st&2nd were using the buddipole dipole. Which works well, I contacted an Oklahoma person who gave me a 59 the other day with the buddipole, and heard NY state and Michigan, etc.

The next project is probably to figure out how to get something up more permanetly (family willing).

-------------------

Final yagi notes...
-The first driven element SWR readings are on another post.
-After figuring out I had a bad UHF crimp the other night, today's reflector element SWR are as follows...
--To start, the original length of 10" beyond the dowels was at 12.986 = 1.2
--I had calculated that my best resonant freq should be at 13.573 for the reflector in order to be 5% lower than the driven - presuming I could get the driven close to where I wanted. The driven set the other day could be better, but it was close.
--So I needed to go up 0.587K, again the trimming for this yagi seemed to be 1"=1Khz - I'm not sure if that's always true on all yagi's, but it seems to hold pretty true for this project. So I needed to cut off approx 5-1/2" or so. I started by measuring 6" from the end of the dowel and cut off the remainder (mostly to make sure they were exactly the same on both sides). And when I was done, I found out both cut pieces were 5".
--The antenna went up and swr was checked. The best resonance was 13.490->13.525 = 1.2
--Down again
--I was afraid to cut off anymore, but I decided to take off 1/8" to see what that would do, because it was already so close.
--Up again
--Best resonance, 13.505->13.535 = 1.2
--But I wanted something nearer to 13.573, not at the end of my 1.2 range.
--Down again
--I got brave and cut off 3/8" after doing some validations that seemed like the 1"=1K was still true.
--Up again
--Best SWR, 13.515->13.560 = 1.2 And that is close enough. I'm leaving it there.

-So I removed the UHF temporary wiring and connected the permanent long wire from coil to coil on the reflector. Then I took the coax and connected it to the driven and decided to cut off some more. I wanted the best resonance to be around 14.287 (middle of General SSB). So some more calcs and off came some more, leaving 7/16" off both ends.

- Best resonance was 14.210->14.234 = 1.1 !!!!!!!!!!!!!!!!!!!!!!!!!YIPPIEEEEEEEEEEE
Close enough! And to check the higher end 14.350 = 1.8 - not to bad, it would be nice if it was better, but I'm not taking any more chances with cutting the wires to short.

I think the picts I've uploaded so far are enough for anyone to duplicate the steps. Hopefully so.

And thanks be to KJ5VW for the initial project. I know he copied someone else from a while back - but even though I complained about not having some real explicit instructions, without him and those he gave (which were good enough), I would never have been able to build this.
Thanks

Yagi - I thought today it would be finished

nospam@example.com (John) — Sat, 15 Nov 2008 22:57:16 -0700

Due to a lack of dedicated time to work on it, I certainly thought an almost full day to finish it up would be enough - but I was wrong. Actually I was wrong about having a full day. It took a lot longer to get all of those leaves up first than I had expected. So about 2pm I started on the yagi. I had 90% of the elements done. I had cut the wires from the coil out to the ends on all 4 ends. The reflector got 10" off the ends (instructions said he ended up with 6") and the driven got 2" off the end (instructions said to start with 2"). I also had the wires cut for the driven, to go inward from the coil to the center where it would meet the feedline (except the feedline part wasn't started yet). And I had a wire cut to go from the coil to coil on the reflector, but the instructions said to put that on after you made the reflector resonate lower than the driven, so it wasn't completed (only one side had a spade connector - the other end was left longer and without any connector so I could make it perfect when it was all together and was ready for it).

So I attached the elements to the boom-base(s). Oh yeah, early on in the instructions it said to buy 1-1/2" and 1-1/4" bolts. Well, I've mentioned them before, but when I went to attach the 1-1/2" bolts through the dowel and through the base - they were too short. So I had to go buy 8-32 2" brass bolts (I already have the washers and nuts). And I have a dipole called the 'buddipole' which came with a tripod and mast. I figured I could use this instead of buying another mast. So I also bought a 3/8" to 1/2" pipe thread - adapter, and u-bolt for it. I didn't need the 3/8" part, but because it was smaller I thought it woud clamp to the boom nicely. It did, but because the outside OD was smaller at the top, when I bolted it with the u-bolt, and attached the whole thing to the mast, one side tilted down because the u-bolt was holding the adapter at an angle, thus the angle transfered to the whole yagi when it was screwed onto the mast. Anyway so I then bought a 1/2" x 1/2" pipe thread adapter and attached it instead. The u-bolt didn't like the extra girth of the 1/2x1/2, but I managed to make it work. So, after getting the elements attached to the boom I decided to attach the UHF to the element wires. I had thought about what to do, and I almost went with some kind of 'project box' where everything would be watertight. But I decided that a blank face plate for a wall outlet would do fine and I'd caulk it when it was working. I marked it up and drilled holes - the main hole I didn't have a big enough sized bit so I had to kind of ream it with other bits to make it large enough. I soldered the red into the center and wrapped the black around a mounting 'machine' screw for the UHF and then attached the face plate with screws to the mast and base plate. It's now pretty secure and after some caulk should be fine. If I leave it outside, I'll use some putty to keep the water out of the top connector. It all worked out well and I was pleased at how it was coming along.

So now for the fun part. I connected a coax to the UHF and the boom to the mast - that wasn't to fun, and raised it up. Silly me, I had forgotten to guy the mast and over it went. I caught it just in time to keep anything from crashing or breaking and scolded myself for that oversight. So then I brought the mast down, guyed the thing and sent it up again. I hate guying when there is only 1 person. Although I've realized I can make it easier if I use multiple levels of guy ropes. The first one was put at the lowest mast section, so even with wind, the whole thing can't come over as I send up one section at a time, and add guys at other mast section points.

Well, now came the moment of truth. I connected my MFJ 259B to the lower end of the coax and set the switch to 10-27, turned it on and dialed it to around 14Mhz. I found the best swr at 13.942 at 1.2, and I was impressed. It's about what the instructions said ... "the driven should resonate below 14.000 Mhz...". I'm a General Class right now and I don't know CW, so I'm stuck on SSB up at 14.225-14.350 so it has to have good swr up there. And up at those levels the swr was 3.1-4.4, so I had some wire to trim. Down came the mast and the instructions suggested that approx 1" should be close to 100K up in freq. Since I needed about 280K in difference I decided to cut off 1" from both sides to start. I sent it back up and tested swr again. The best swr I could get was 14.030 - 14.098 at 1.3, and that's pretty good, except it's out of band for me, but 14.120 was at 1.4 so I knew I was close. So down again and I cut off 1" from the end on the red side and went to the black side and it was just a bit longer than the red. So I ended up leaving the same amount on both ends - out beyond the dowel end - leaving 7/8". I didn't pick that, it was just what was left after trimming the 2nd 1" on both sides. So up again, the best swr was 14.200 at 1.2, whooooo! I was pretty close if not close enough. I moved around a bit and at 14.227 I was still at 1.2. And at 14.349 (adjusting the MFJ to an exact freq is difficult, so I got close enough), the swr was at 1.9. Well, I wasn't sold, but I'm close enough to move on and I might come back and take a bit more - much much less than before.

Well, I needed to make a trip to a store before it closed and I decided this would be a good point to stop. So I brought the antenna down and took all of my stuff inside and left. When I came back it was getting close to sunset and I realized I had to be quick. Originally I had wanted to use the UHF and red/black wires I'd attached to the driven element, for setting and testing the reflector element. But since I had taped the wire with electrical tape (per instructions) and screwed the face plate to the boom, I decided to use another UHF and solder another wire on it. I did that, and the solder on both jobs went smoothly on and looked good. I attached a black wire to the outside screw hole. Now remember that I had not put any wires on the inside of the coils on this reflector element yet. So I cut some, quickly wrapped it around the screw on the coil and taped it into place into the center of the beam. So what I had were 2 wires merging on both sides of the UHF. I twisted them together (on both sides) and thought I would be ok since the instructions had made a comment that as long as both were the same length..... well I wasn't sure but it was the easy way. So, I connected up the coax to this new UHF on the reflector and sent up the mast. I connected it to the MFJ 259B and the SWR read >25. What? Why? What was so different? Was it because of the twisted wires? Well, I've gone on long enough for this post. But suffice it to say that I brought it down, removed the reflector UHF and wires, removed the driven UHF and wires, took those and put them on the reflector element and up again, the SWR was >25. I was so frustrated. I figured it must be the coils. What else could it be? Could it be the coax? Is there a break in it and the cold made it shrink? I move the dials on the 259B all over, and the I couldn't get the SWR down at all, but I could get some readings to change when I got to the VHF area. 116.57 gave me R=0 and X=191 but SWR was still >25. Incredible! How in the world could the front one get 1.2 and the back one get >25 with the other readings staying at R(Z)650>? I guess I am out of my league. So I brought it down, unhooked the wires and the UHF and face plate, put them back on the front and decided I should test the front again. By the way, it's DARK now. So I had to go get some work lights from the garage in order to see the 259B and what I was trying to do.

Ok, so I'm expecting to see something close to what I saw before and it shows me SWR >25. I am beyond confused.

I took it all down, every last part, removed wires, removed elements, disabled the tripod and mast and took them all inside, that was enough.

After it was all put away I grabbed the 259B to remove the batteries - I use rechargables - and as I did so, hit the Power button. It came on and showed 5.?? SWR. What? No cable, just dead air and SWR of 5+. So I grabbed my coax and put it back on. It showed something close to that also. I'm not sure what's going on, but it's looking like the 259B. And I wanted to make sure the cable was secure so I tightened it and the SWR went to >25 immediately. WOOOOOOW, what a revelation. I did it again and again, loosen then tighten, loosen then tighten and each time I tightened, it pegged >25+, and when I release it by just a 1/4 turn or less, it came back to normal.

I could have gotten this thing done today if I would have noticed this outside. Either my 259B does not like the coax tightened - or more likely my PL-259 on the coax is not crimped well and when fully tightened it pulls the cable way from the connector and things get out of hand. I'm not sure which, but it's pretty obvious it's one of the two and I'm betting it's my crimping skills or lack there of.

I'll have to see what I can do tomorrow and see if I can not only get this done, but maybe, just maybe try it out.

Here are some pics from today...

Shot of beam on ground just as I'm getting started.	Another angle of the whole beam on the ground.	Another shot of whole beam.	Driven coil, black side - coil wrapped in electrical tape.	Driven, black side, off the end of the dowel.
Center of driven before UHF	Driven before UHF	Reflector element, 10" off the dowel.	Driven red wire before any trimming.	One of the reflector coils - no wire going toward center
Dowel mounted to base plate with 8x32 2" brass.	Center of reflector before any testing.	3/8" to 1/2" pipe adapter	3/8" to 1/2"	Reflector - other side before any testing
UHF face plate mount	UHF face plate mount	UHF face plate mount - red wire soldered on.	UHF face plate mount upside down	UHF face plate, red and black attached
UHF face plate finally attached	Up in the air, testing driven.	Reflector - temporary UHF for testing	Reflector UHF for swr testing	Reflector - another shot of UHF for swr testing
The new 1/2" to 1/2" pipe adapter to keep the boom level instead of 3/8" to 1/2" adapter.

Yagi dowels attachments

nospam@example.com (John) — Wed, 12 Nov 2008 22:39:14 -0700

I was able to get the dowels attached to the boom today. I wasn't sure if the wire that goes on the dowel length wise (the element) was supposed to go on the top, or on the side (or front) of the dowel. It doesn't say. And if on the side, doesn't the wood get in the way of the reflector element and the driven element? Additionally if on the side, the rear reflector would have to be on the back and the driven would have to be on the front (thus with wood possibly interfearing. So that didn't seem right, but because the coil(s) have 2 bolts in them, and the rest of the wire for the element has to attach to those coil bolts, it mattered how I mounted the dowels with reference to the coil bolts.

Anyway I asked another and they thought the wire should be on top of the dowels. So I drilled the holes into the side of the dowels and through the side of ends (the ends are 1"x2" oak attached to the boom). Although it looks like I need longer screws to go through the dowel and the 1"x2" oak end(s), because the 8x32x1-1/2" are just not long enough.

With the instructions I'm following, I'm not sure how they made this. But at least it gave me the basic overview and tried to give some details and I just have to work out the rest. The details just aren't so detailed.

Yagi progress

nospam@example.com (John) — Mon, 10 Nov 2008 23:16:30 -0700

Well I've been slowing working on the new 20M yagi. I have been taking pictures and I'll add them a bit later. As mentioned before I couldn't find any Oak 4' 5/8 dowels around here (not at HomeDepot nor Lowes), - one could waste a lot of time looking around. But HD did have some "hardwood" 4' 5/8" round dowels. I don't know what 'hardwood' means, but I broke one of them, so it's obviously not very hard.

So I ended up near Lowes and bought one from them. Their 5/8" 4' long says it's "Poplar" wood. It's about the same as the HD pieces. I've shaved off the ends to fit into the 1/2" pvc, and I've wrapped the pvc with the 7'+ long wires as instructed and wrapped those in electrical tape. I also took the 8'6" beam and attached the 2 end pieces (24" long) and the round dowels will attach to these - but I've not done that part yet. I need to clamp the elements onto the ends and drill holes to hold them to the beam. Once that is done then I'll need to finish wiring it.

I'm thinking I should put some wood sealer on this stuff so it doesn't rot, it would be rather easy to replace, but why go to that effort after making it once?

I still have the question about whether the beam should be 8'6" or 8'3-1/2", but I may just have to test swr and reception/transmission to determine what's best.

Yagi parts purchased

nospam@example.com (John) — Thu, 06 Nov 2008 00:33:07 -0700

Well I went to Home Depot today and I was pleasantly surprised that they had quite of bit of what I needed. I found some 5/8 oak dowels but they were only 3'. They did have some 4' hardwood (not oak) but I guess that will have to do. If I want 4' oak I'll have to order them from an internet site and who knows how long that will take - and since winters here - I can't work out in the back yard as normal. Anyway they had the 1"x2" oak for the boom and for the 1"x2" x 24" base plates. I also got a 4' piece of 1/2" sch40 pvc for the (4) 4" pieces for the coil assemblies. I also found the (8) #8-32 x 1 1/2" and (8) #8-32 x 1 1/4" brass bolts, brass washers and brass nuts. The original website didn't include the washers in the parts list. But they are called for in the text. Also the parts list says to buy a 1"x2"x8' 6" oak boom. But then later it says to "Cut a 1" x 2" piece of oak to a length of 8' 3-1/2" ", without any explanation as to why they said 8'6". And that kind of stuff just confuses me. But I bought a 9' piece of 1"x2" oak piece and I'll have to decide which length to cut it. I'll probably go with the 8' 6" and test the final outcome, and then if it's not right, reduce it to the 8'3-1/2". But in my education with this so far, I'm pretty sure there is some calculation to say how long, or how far apart the elements on the driven need to be from the reflector, and so maybe I'll spend some time looking for that information and that might tell me which size to cut the boom. In addition something that was never spoken about in the instructions was the boom orientation. Perhaps they think I'm smarter than I am? But are we supposed to put the 2" wide and the 1" high when attaching the parts, or should I put the 1" wide and 2" high. If you don't understand what I just said, essentially I'm wondering if the boom should lay on it's 2" side or 1" side? However, since I have just a bit of a clue I know that a piece of 2x4 is stronger in a horizontal configuration when the 2" is down and the 4" is to the side. So using that concept, this piece of 8' 3-1/2" would be stronger having the 1" on the bottom and top, and the 2" out to the sides. The reason this was important to me was so the boom is able to hold up to winds and such, but more importantly I couldn't find any "L" brackets that were only 1". At HD I found 2" wide "L" brackets in the "Fasteners" isle. So by placing the 1" on the top and bottom, the 2" "L" will fit nicely against the side of the boom and to the "Base Plates" as they are called in the instructions. The "L" brackets I bought are kind of short, I hope they are long enough to hold the "base plates" as instructed (the 2nd hole is to be 1" from the end of the base plate). does that mean the "L" bracket needs to go from the boom out almost 1 foot? Or does it mean that this 2nd hole will not be touching the "L" bracket at all? But finding all of this at Home Depot wasn't to bad. I'll have to add an image here of the pieces in case anyone else needs some clues. But my HD trip cost me $43.15 (tax incl).

So, in the instructions it says to use a 8-32 bolt,washer,nut to fix the "base plate" to the "L" bracket which is attached to the "boom". Which one of the #8-32 (1-1/2 or 1-1/4)? It doesn't say. But in one of the pictures it shows that attaching the dowel to the PVC to use the 1-1/4", so I guess that leaves the 1-1/2" bolts. I tell you, those instructions are not very clear, but I'm making progress anyway. It just takes looking over the page and trying to deduct what was meant. But, additionally that same photo which shows using the 1-1/4" bolt also shows that the #22 awg wire (I'll reference this purchase later), goes around the pvc (ok fine), but it then shows #14 awg wire from the coil out to the end of the dowels. But in the parts list there isn't any mention of #14 awg, just the #22 awg. So what gives? Does it matter? I'm new enough that I don't know if any piece of wire - no matter the guage - is ok, or if size matters? Perhaps it doesn't matter but it's confusing when it's not said one way or the other and it's just in a picture.

So I bought 90' of "Hook-Up" wire from Radio Shack. Apparently they have stranded "Hookup" and solid "Hookup" and I sure can't tell why it's called "Hookup" as opposed to any other "22 awg" wire. But I'm trying to follow this set of instructions to the tee, so I found and bought the "Hook-Up" type and also the spade terminals at RS. That cost me another $9.57. I might have saved a few cents buying the terminals at AutoZone or Checker or maybe even Walmart but then I'm wasting more gas which is more than what I would save. And I was getting worn out doing all of this shopping.

And the only reason I'm including prices is because the original (written who knows when) said this costs less than $30 to make. But at the end of 2008 it's material list is up to $52.72 which isn't terrible. But for something like this there is a hidden cost. An antenna analizer which is pretty necessary for getting the wires trimmed correctly. I found a MFJ-259B on ebay for $225. Not a bad price (used 4 times per the owner). So the real cost of the antenna is now up to $277.72.

Maybe I can get some pictures soon and begin the rasping of the dowels and perhaps get the boom and base plates cut to correct length. Maybe this will go together pretty quick?

20M Yagi

nospam@example.com (John) — Wed, 05 Nov 2008 02:40:12 -0700

I found a 20M 2 element yagi I want to build (http://uts.cc.utexas.edu/~hansongr/Miniyagi.htm). The instructions sound like you have to have a clue, which I don't. But I have the parts list (some were ommited in his parts list), but the hardest thing about building is just finding somewhere that has all of these items. This particular yagi needs 5/8" 4' oak dowels and 13' 1 1/4" closet pole - I'm not sure HD or Lowes has these things in the length (or more) that I need, but I'll check tomorrow. It calls for 30+ feet of #22 plastic covered hook-up wire. What in the blazzes is 'hook-up' wire? I know of 22awg, but does this mean stranded or solid, or does it mean something else entirely. ?? Like I said, finding stuff for the first time is the hardest part of my - short - ham experience. Isn't there somewhere that carries everything I need?