Towertalk
[Top] [All Lists]

[TowerTalk] Estimating RF Choke impedance

 To: , [TowerTalk] Estimating RF Choke impedance "Tod -MN" Thu, 29 Jul 2010 02:04:27 -0500 mailto:towertalk@contesting.com>
 ```This is a follow up to Jim Brown's note on my measurements of choke impedance using a power meter. As Jim pointed out, the circuit he used on page 31 of his tutorial allows one to measure the impedance of a choke made by winding coax around one or more combined cores. Jim's circuit used a signal generator and an RF Voltmeter [in his case a spectrum analyzer]. By making measurements at several frequencies one can get an idea about performance of a choke over a band of frequencies. Since I happen to have an HP spectrum analyzer and tracking generator I decided to see if I could generate and photograph curves of the impedance of a choke over a frequency range. Jim's "Choke Cookbook" suggests that one use seven turns of coax through five combined toroidal cores of type 31 material to make a choke for 160m and 80m. Since I had a combination of six such cores on hand I decided to make a seven turn, six core choke which I would then measure across the 160 and 80 meter band In addition to the measurement of the choke I decided to measure some small resistors in the same circuit. The curves for the various resistances would allow one to visually estimate the impedance of the choke when the choke curve was compared with the resistor curves. The result of this simple experiment has been posted on my web site. If you have an interest in this you can click on the link below to see the pictures and commentary. Estimating RF Choke impedance www.k0to.us/HAM/Balun/Estimation%20of%20RF%20choke%20impedance.pdf Tod, K0TO _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread [TowerTalk] Estimating RF Choke impedance, Tod -MN <= Re: [TowerTalk] Topband: Estimating RF Choke impedance, DAVID CUTHBERT