AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |
Back to Blog
How To Test A 49-1 Unum3/12/2021
Common sence would tell me its junk But never had a balun before so I have not a clue Bought to set up an 80 meter dipole, have made several over the years but never used a balun.If you have an antenna analyzer, connect it to the input of the balun and connect a 50 ohm resistor across the antenna terminals.
Lacking an analyzer, connect your rig through an swr meter to the balun and connect a power resistor (20 - 50 watts, non inductive) across the antenna terminals. Cant do that Connect your antenna and see if it will tune ok, not best, but last resort. You will also need a short jumper wire, an 8 length of 16 wire will do. Test A 49-1 Unum Series To MakePut the two resistors in series to make 50 ohms and put that across the output of the balun. Pick the desired operating frequency and you should see a 1:1 SWR on the analyzer. Now attach the one end of the jumper to the center of the two resistors. A more severe test is to attach the grounded jumper first to one side of the series pair, and then to the other side, and check how much the SWR changes. A pair of 100 Ohm resistors in series would be better. Bought to set up an 80 meter dipole, have made several over the years but never used a balun.. The fact that huge numbers were sold for this purpose does not enhance their suitability, it just shows we (collectively) dont understand baluns very well. If the objective is the reduces feed line radiation (and related effects), then a balun that tends to force equal but opposite phase feed line currents is needed. A voltage balun tends to force equal but opposite phase feed line currents ONLY when the load is perfectly symmetric (or balanced), a current balun tends to force equal but opposite phase feed line currents for ALL loads. A 1:1 current balun with high common mode (or choking) impedance is better suited to the application.
0 Comments
Read More
Leave a Reply. |