> Quoted from Fred (“Skip”) K6DGW… > (1) The MFJ-259x series of antenna/feedline analyzers havean N coax > connector. Using the BL2, you can connect it to the balanced ladder line. How > were you planning to connect it without the balun? As you state it, it does > not sound like a reasonable experiment design.
Not sure what you are saying above. After the e-mail I sent, since the WX was so nice at 77 degrees, I went out to do the measurements. I attached the 450-ohm ladder line to the balanced terminals on the BL2 and the BL2 was itself attached to the MFJ and also the VA1 via my BNC to UHF (PL-259) adapter. I first did resistor checks at 3.5 MHz to find that all was working as it should in this setup. With 200 ohm resistor on the BL2 terminals using 4:1 I measured 49 ohms with essentially zero X (reactance). In 1:1 mode, I read 203 ohms and 1 or zero on X (it was changing back and forth). Then I measured with the actual antenna by disconnecting the ladder line from my DXEngineering 4:1 balun and connecting it to the balanced terminals on the BL2. I was on a ladder doing this so I decided not to take too many measurements and focused on 80-meter band only. Within a reasonable error factor, the numbers I found for 4:1 switch on BL2 were consistent (close) to the Bypass SWR reported by my KAT500 for the same frequencies: 3.501, 3.6, 3.7, 3.8, 3.9, and 3.99. Most of the 1:1 measures I made were too high SWR (~15:1 and above). > > The MFJ-259x and VA1 are almost guaranteed to give non-identical results. If > they are large differences, youhave some other problem. If they are small, > they are essentially meaningless for your application. Hope this all helps. Yes, all of this helps. Later this year I will be doing some experiments with the BL2 — not for ham radio, more for my physics interest. I will be measuring the heating of the ferrite core on the BL2 using my Fluke Infrared Temperature gun. I have already measured the time for the ferrite core to come to thermal equilibrium in two different heat baths. An air conditioned room versus the overheated garage on a hot summer day. That was the very first thing I did with my BL2 after I finished building it. Yes, the MFJ and VA1 always give me different results but they are usually close. The VA1 actually is useful because you can easily determine the sign of the reactance where as with the MFJ you need to change the frequency (like moving it up) to watch which direction the reactance term changes. PEH ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
