Hi Vic You can use your MFJ to measure the impedance of the balun. Connect one of of the balun (short both wires together) to the center of the MFJ coax connector and the other end, shorted together, to the shell of the connector. Use the MFJ to measure the impedance of the inductor formed at the frequency to be used, say 1850 kHz. If the impedance is 5 or more times the 50 ohm line impedance, you have a good balun for 160m. If that is the only band you expect to use it on, you are done.
If you expect to use it over more bands, say 80 and 40m as well, tune the MFJ to those bands also and make the same neasurement. With a good core, the impedance should hold through these bands as well, or even be higher. Good luck and 73 Bob N6WG -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Vic Rosenthal Sent: Wednesday, April 06, 2005 3:39 PM To: Elecraft Reflector Subject: [Elecraft] Balun question I made a simple 1:1 receive-only balun for 160 meters by winding 9 bifilar turns of no. 24 enameled wire on an FT37-77 toroid. I connected a 50-ohm resistor to the output and my MFJ antenna analyzer to the input. On 1.8 MHz it shows a resistance of 50 ohms, an inductive reactance of 1 ohm, and an SWR of 1.0:1. My question is, did I make a 'good' balun? Are there other tests I should do? It's job will be to isolate a receiving loop antenna from its feedline, to keep the nulls deep and reduce noise pickup. The RANT feature of the K2's 160-meter option has made it possible for me to use a ferrite loop which is only 21 inches (53.3 cm) long and has a s/n ratio much better than my inverted L transmitting antenna, even without the balun. I'll put details on my website after I finish testing it. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
