2 meter slot-cube antenna
| Feb 17th 2019, 15:12 | |
K9RJTotal Topics: 0 Total Posts: 0 |
Seems like there are several different forums for this antenna. Is this normal? |
| Feb 26th 2019, 22:28 | |
K1WCCTotal Topics: 0 Total Posts: 0 |
Yes, this was a poorly written article. The BOM is not complete, and there should have been a line drawing included. I'm building it, and hope it comes out ok. Tnx for the "correct" parts list. |
| Feb 27th 2019, 08:46 | |
W1VTSuper Moderator Total Topics: 0 Total Posts: 0 |
http://www.arrl.org/files/file/QST%20Binaries/Jan2019/Slot20Pipe20in%20Inches.jpg Picture with dimensions labeled. |
| Mar 12th 2019, 20:23 | |
ve7dvb1Total Topics: 0 Total Posts: 0 |
Got a message from W1VT link: http://www.arrl.org/img/file_types/missing.png. The issue I'm having is that instead one of the 8" on the horizontaI am using the 6" on the horizontal (into the Tee) as the top and bottom cubes each can't be built using 2 (8") and 2(8.5"). There is indeed an 1/8" gap inside of the CPVC coupling so the height of the risers has to be 7 to match the length of the feed point pieces. Fun project though. |
| Mar 14th 2019, 20:54 | |
KC3LMVTotal Topics: 0 Total Posts: 0 |
Can this Slot-Cube antenna for 2M be scaled up to a 6M antenna. Is there a conversion factor to go to 6m? |
| Mar 16th 2019, 10:00 | |
KD5FXTotal Topics: 0 Total Posts: 0 |
I built it from the article and QST online picture. Checked and triple checked all my dimensions. It was resonant at 154 MHz. I tried what W5NBC said to try and put a tab of 1" wide AL foil that is 4" long (just one) on the corner opposite of the match and it now tunes to 146!!! With a bandwidth (2:1) of 145 to 148. So next I will flatten a piece of 1/2" tubing and replace the AL foil with that. |
| Mar 23rd 2019, 17:38 | |
KB9VSBTotal Topics: 0 Total Posts: 0 |
Thanks for the Update! |
| Mar 30th 2019, 17:39 | |
AC8QBTotal Topics: 0 Total Posts: 0 |
Using AL foil works because it's emicivity is different than copper. A copper sheet only changes the diameter of the tube. I am making a new version with 0.050 " added to vertical members of the cube. I tried to add C to tuning but even with a gymic (twisted pair of insulated wire) was too much C. 3rd thing is to use an open stub and see what the smith chart looks like. |
| Mar 31st 2019, 15:38 | |
KC3LMVTotal Topics: 0 Total Posts: 0 |
I was able to find the information on Scaling antennas from and article by W5ALT " Antenna Notes For A Dummy" From that artical and with some math help from my Niece Amy Sefcheck I came up with the following. NOTE I have NOT built or tested it yet 6 Meter Slot Cube Calculation WL = Wave Length, Freq Old = 146.5 MZH Freq New= 52 MHZ WL old =984/ Freq old = 984/146.5mhz = 6.7167 WL new =984/Freq new = 984/52mhz = 18.9230 SF =WL new/WLold = 18.9230/6.7161 = 2.8173 If we round the SF to 2.75 what is the corresponding Freq New 984 / (WL old * New SF) = New SF freq 984/ ( 6.7167 * 2.75) = 53.2729 2 Meter 6 Meter Amount of ½ “ pipe 8.5 * 2.75 = 23.375 23.375 * 6 = 140.25 L in 8 * 2.75 = 22 22 * 2 = 44 Lin 6 * 2.75 = 16.5 16.5 *2 = 33 Lin 4.25 * 2.75 = 11.6875 11.6875 * 2 = 23.375 Lin 1 * 2.75 = 2.75 2.75 * 2 = 5.5 Lin Total 246.5 Lin = 20.55 LF = 2 and a fraction of 10’ pipes |
| Mar 31st 2019, 15:57 | |
KC3LMVTotal Topics: 0 Total Posts: 0 |
I have built the 2M Slot Cube with the revised pipe lengths. I made it in 3 assemblies. The top loop, the bottom loop and the feed point loop. I did all my work on a capped block wall as it is relatively flat. Then after the assemblies were relative parallel and square I combined them together. I had to do a bit of fussing and adjusting with the finished assembly to get everything relative parallel. I have only tested the antenna attached to a 1.5 " x 4' piece of PVC on top of a 6' ladder. The antenna was cocked downward about 30 deg. It worked marvelously. I hit a 2 repeaters 18 miles away on 20 watts. As far as I can tell from my MFJ SWR meter the SWR is quite good maybe as high as 1.5 : 1 on 50 watts. Ill be doing more testing with it the end of April when I meet up with a friend with a High end Analyzer |
| Apr 9th 2019, 09:39 | |
WC0GTotal Topics: 0 Total Posts: 0 |
I built this antenna last week with no problems. One thing I did notice while testing it was how sensitive it is to nearby objects. When mounted in the clear the lowest SWR is 1.2 to 1 at 145.8 MHz. When mounted within a few feet of of my house or a tree the SWR jumps up to over 2.0 to 1. SWR was measured using a Rig Expert AA 230. Total build time was about an hour, |
| Jan 18th 2021, 20:38 | |
KE8KZUTotal Topics: 0 Total Posts: 0 |
Do you have a pic of what the tab looks like? Thank you! |
