WB0SMX

  43′ Vertical – Part 5 – Matching Network Filed in Antennas on Jun.20, 2010 Next on the list for the 43′ vertical project was the base matching network, to allow reasonable matching to the rig on all bands from 160 meters through 6 meters…   I started by mounting the 4:1 Unun from MFJ on a fiberglass plate, to give it good high voltage characteristics.  This Unun is at a very high impedance point on 160 meters, so develops some very high voltages (up to 5000 volts or more, depending on power levels). The Unun was attached with a 1/4″ x 20 screw through both boards, forming a sandwich.  It is used to drop the high impedance down to a more manageable level on the ham bands.  It basically divides the impedance at the antenna by 4.   Because the coil needs to be about 46 uh, it is too long to fit all in one piece.  So it is cut in two sections and mounted seperately.  By putting the two sections in series, the inductances still add up.  There is about 54 uh total to work wit

  New Etching Solution Filed in homebrew on Jun.20, 2010 When I started working on my matching network for the 43′ vertical, I needed some mounting plates made from fiberglass (high voltage resistant…)  I had read in the QRP-tech yahoo pages that you could use a combination of Hydrogen Peroxide and Muriatic Acid to do the etching.  I had use Ferric Chloride before, and found it to be messy, and somewhat of an environmental hazard.  You really don’t want to pour that stuff out just anywhere… So I mixed 1/2 cup of hydrogen peroxide with 1/4 cup of muriatic acid (like you use in your pool).  I put the copper plated fiberglass into the solution and gently scrubbed it with an old toothbrush.  It only took about 5 minutes for all of the copper to dissolve.   The result was a nice clean piece of fiberglass, and some easily neutralized (with baking soda) etching solution that was safe to dispose of.  Migrated Comments: 2 Responses to “New Etching Solution” Sean O'

  43′ Vertical – Part 4 Filed in Antennas on Jun.20, 2010 When I arrived on Friday, I got out the post hole digger and dug a hole about 2 feet deep. The post was set into the hole and prepared for cement. The radial plate was attached to fix the height above ground level.   The post was leveled on Saturday, and cement was mixed and poured into the hole.  Only one 60 lb. bag was used, as this was a pretty small hole.   After the cement dried for several hours, the remaining few inches were filled with dirt from the hole.  This was done to facilitate moving the antenna to a different location at some point.  I could just cut off the post below ground level and not have to worry about removing the cement portion.   I wanted to be able to telescope the tubing sections up and down, so that the antenna could be easily lowered when we were not up at the ranch using it. But when I started sliding the tubing sections together, the second and third sections became stuck so bad that

  43′ Vertical – Part 3 Filed in Antennas on Jun.20, 2010 The next step was to attach the aluminum tubes to the 4×4 pressure treated post for mounting in the field. I used some 2″ conduit brackets and some 2″ PVC parts to do that.   For the top of the mount, I used a piece of 2″ schedule 40 PVC pipe.  At first I tried to just compress the pipe around the tubing, but it would not compress enough.  So I used my coping saw to cut a slit in the tubing, to allow space for it to compress.  That seems to have worked nicely.   For the bottom, I use a 2″x1″ schedule 40 bushing, with a 1″ x 3/4″ threaded adapter. I thought I might be able to clamp this part as well, but due to its complex structure, it was not possible to compress it.  I will rely on the clamp and copper pipe into the ground to keep it in place, and let the antenna sit on top of it.  That should keep the bottom for hinging out in the wind.   At this stage, I headed up to the ranch to plant the pole in the ground.  O

  43′ Vertical Antenna Construction – Pt 2 Filed in Antennas on Jun.06, 2010 I was hoping that the aluminum tubing could be clamped together at the joints without any modification.  As it turns out, the tubing is too strong to clamp without cutting a relief slot in the outer tubing.  So first, I needed to find two points around the circumference of each tube, to get the slots reasonably lined up across from each other. To do this, I wrapped a piece of paper around each tube, and marked the beginning and end of the wrap around the tube. Then I took off the paper, and measured between the two marks.  Half the distance was marked off as the location of the second slot.  The paper was then wound back on the tube, and the new marks transferred to the tubing. Then the tubing was slotted with my favorite coping saw. After deburring, the next tube was trial fitted into the first, and a stainless steel hose clamp was attached.  This time it held very well. The next step was to deter

  43′ Vertical Antenna Construction – Pt 1 Filed in Antennas on Jun.06, 2010 I’m looking for an alternate antenna for HF operation at the Ranch . I currently have an 80 meter doublet installed at about 30 feet above ground.  That works pretty well with the balanced feedline, but I would like to have an alternative to provide some diversity. So the thought is that I will install a vertical to complement the horizontal doublet. Perhaps when one antenna isn’t quite up to the job for a particular path, the other will be better.  Verticals have long been recognized for their better DX performance, due to their typically low angle of radiation (at or near design frequencies). My criteria is an antenna that works reasonably well on 160 – 6 meters, with low cost and low complexity.  It should be self-supporting (even with our consistently strong wind at the ranch), and require little maintenance.  Probably one of the most discussed antennas on the web today is the 43′ vertical.

  Receiver Noise Bridge – Pt 4 Filed in homebrew on Jun.04, 2010 Once the electrical build and calibration were complete, I used Visio and Photoshop to create some graphics for the control panel.  I also made a graph to convert what the dials say to actual values on the HF and 6-meter Ham bands. The front panel has a resistance control in the top left, scaled from 0 to 287 ohms.  The reactance scale is calibrated for ohms of reactance at 10 mc.  The graph is used to convert this reading to other bands.  The reactance scale is from 67 inductive to 1500 ohms capacitive at 10 mc. The lid contains a graph for conversion of readings to other ham bands. And here is the box with the lid closed… Migrated Comments: 2 Responses to “Receiver Noise Bridge – Pt 4” Peter Says: September 13th, 2016 at 3:11pm Where’s u get the schematic, Thanks wb0smx Says: September 13th, 2016 at 4:41 pm It’s been a long time since I built t