Roger, your 56' tower is resonant at about 4.1 MHz - Give or take a bit. I'm modeling it with a 1' x 1' four legged tower. To shunt feed it on 3.5 MHz a #12 wire running 1' from the tower and attache
Has anyone here had good results from any of the non-MFJ impedance meters? I have an MFJ-259 and 269 and they are handy to have but not very accurate in my experience. I have made lab measurements ag
Roger, the strength of your aluminum mast can be calculated. Based on the antenna wind load and the maximum wind in your area you will know if it's going to survive or not. The book Physical Design o
Dave, rather than plan for graceful mast failure we can design for no failure. Designing these things is not difficult and beats worrying everytime a heavy wind comes up. I had a rather flimsy wooden
Gene, does anyone run simulations or calculations on lightning strikes. A common direct stike is 100 kA with a risetime of 8 us, correct? If so, using an inductance of 200 nH/ft, the voltage drop alo
Roger, here's a link to some good information on tower stresses: http://www.heightstowers.com/tower_specs_and_tutor.htm http://www.google.com/search?q=antenna+element+bending+moment+formula&hl=en&lr
For all of you mast users: Here is a link to spreadsheets to figure mast survival. http://www.realhamradio.com/Download.htm Download the Spreadsheet Unzip it Rename the .wk1 files .xls files if your
I'm so bad at putting together anything other than a PL-259 that I order cables from Pasternack. I guess I don't have the knack. Dave --Original Message-- From: kc8hz@hotmail.com To: towertalk@contes
Adding 50 feet of lossless line will not change the VSWR. It will rotate the impedance (seen at the TX end) around the Smith Chart. If the tuner can handle the 'new' impedance as well as the 'old' im
Adding the top hat wires will increase the radiation resistance. If the VSWR was 1:1 before it will be higher after the wires are added. The wires should just about triple the radiation resistance. G