Re: Topband: How to determine impedance

2018-01-31 Thread Martin
Topbanders, thanks for all the valuable input. So far i can say the beverage was of great help in the past 160m contest although it still is not optimized. At DL0WH, we didn't work much, we rather tested the performance. Conclusion was: NW works great, SE ..uhm.. not. The K9AY loop

Re: Topband: How to determine impedance

2018-01-29 Thread Grant Saviers
done. 73, John W1FV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Martin Sent: Wednesday, January 24, 2018 6:28 AM To: topBand List Subject: Topband: How to determine impedance Topbanders, for the construction of the beverage ( a 2 wire reversible bevera

Re: Topband: How to determine impedance

2018-01-29 Thread John Kaufmann
esting.com] On Behalf Of Martin Sent: Wednesday, January 24, 2018 6:28 AM To: topBand List Subject: Topband: How to determine impedance Topbanders, for the construction of the beverage ( a 2 wire reversible beverage, that is) from my post a few days ago i wanted to know how to measure or

Re: Topband: How to determine impedance

2018-01-29 Thread Grant Saviers
Another line Z measurement technique is with a scope and reasonably fast risetime (few nsec) pulse generator. Terminate about a 20' length of line with a variable non-inductive pot or carbon comp resistor selection and drive a pulse at the other end and adjust the resistance for minimum

Re: Topband: How to determine impedance

2018-01-26 Thread Mike Waters
Hello Martin, I have other equations here: www.w0btu.com/bev_ant_impedance-math.html Other charts, matching transformer ratios, etc. are on www.w0btu.com/Beverage_antennas.html 73, Mike www.w0btu.com On Wed, Jan 24, 2018 at 5:27 AM, Martin wrote: > Topbanders, > for the

Re: Topband: How to determine impedance

2018-01-26 Thread Martin
Am 26.01.2018 um 02:42 schrieb Richard (Rick) Karlquist: You don't need to divide by length. You are darn right. I just verified it. I found Zo=sqrt(L/C) on a forum and thought this can't be right because coax like rg58 has C about 100 pF PER METER. So i modified the formula, verified it

Re: Topband: How to determine impedance

2018-01-26 Thread Richard (Rick) Karlquist
On 1/24/2018 3:27 AM, Martin wrote: With both ends open, measure capacitance C of DUT, divide it by it's length ( C' = C/m) . Shorten one end, measure inductance of DUT, divide it by length ( L' = L/m) . Now calculate Z= 1000 * squareroot(L'/C') You don't need to divide by length.

Topband: How to determine impedance

2018-01-25 Thread Martin
Topbanders, for the construction of the beverage ( a 2 wire reversible beverage, that is) from my post a few days ago i wanted to know how to measure or determine the impedance of the open wire. I stumbled across a very simple method some of of you might know , some might not. Anyway, here is