The N-type test loads I received with my Array Solutions VNA2180 were SMA loads screwed to N-type/SMA adaptors! Steve G3TXQ AS-PLS-U Standard Calibration load set PL259 up to 1 GHz $50.00 AS-PLS-N St
Like AC6LA I have no connection to the company, but I note that Danny publishes complex Common-Mode impedance plots for his chokes; I believe that's unique amongst manufacturers. I've checked a few o
Unfortunately that test doesn't subject the balun to the maximum CM stress it might experience in a typical application - at worst it subjects the balun to a CM voltage equal to the full differential
You must take account of the reactive components. If you have only a resistive load, no matter how much you unbalance it you can never generate a CM voltage across the balun higher than the different
Take a look at the voltages in the example I worked using your impedances. There would be no difficulty at all designing balun windings to handle the 452v rms (639v peak) differential-mode signal for
If you derive the expression for SWR in terms of antenna R and X you can differentiate with respect to frequency and determine the conditions for minimum SWR analytically. You'll find that when dX/df
Dan, If you have the time, you might want to try plotting resonant frequency vs height for a linear half-wave dipole and comparing it with one bent into an almost closed square, as in the "cobweb" de
Just found one a plot I did a while ago: http://www.karinya.net/g3txq/temp/dipole_vs_cobweb_tuning.png Steve G3TXQ If you have the time, you might want to try plotting resonant frequency vs height fo
Thanks Dan - I thought I remembered a discussion, but couldn't find it! Suffering badly from last week's "chemo" session at the moment :( Steve G3TXQ I see you beat me to it! You and I discussed this
It's clearly not as simple as a "capacitance to ground" effect. The cyclic nature of the resonant frequency vs height, plus the fact that it is more pronounced over better-conducting ground, suggests
Here are the resonant frequencies I measured of a 10m half-wave dipole on a telescopic push-up mast at various heights above ground in my back yard: 5ft 29.359MHz 10ft 30.499MHz 15ft 30.889MHz 20ft 3
Here are the resonant frequencies I measured of a 10m half-wave dipole on a telescopic push-up mast at various heights above ground in my back yard: 5ft 29.359MHz 10ft 30.499MHz 15ft 30.889MHz 20ft 3
Scale the height by 2 and divide the frequency shift by 2 and it bears comparison with this: http://www.karinya.net/g3txq/temp/dipole_vs_cobweb_tuning.png Steve G3TXQ 20 ft..to 100 ft. But I dont kno
Plus, EZNEC assumes homogenous ground to infinite depth whereas I have this: http://www.karinya.net/bungalow/preparation/prep2.jpg Steve G3TXQ I'm sure if Dan fooled around a while, you could get a c
Some readers may be interested in measurements made on a "real world" antenna - a 100ft doublet centre-fed with window-line. At the shack end of the window-line, the equivalent star-network impedance
Some readers may be interested in measurements made on a "real world" antenna - a 100ft doublet centre-fed with window-line. At the shack end of the window-line, the equivalent star-network impedance
Not sure if this link has yet been quoted in this discussion: http://users.tpg.com.au/users/ldbutler/Line_Diff_Long_Meter.htm Steve G3TXQ _______________________________________________ _____________
Jim, I'll need to dig back through my lab notebooks to see if I made measurements on other bands. A SPICE analysis shows that if you connected that window-line load to the output of an unbalanced tun
Jim, Found a 10.1MHz measurement: Z1 - Window-line Leg 1 to Star Common: 13.7 - j41.1 Z2 - Window-line Leg 2 to Star Common: -2.6 - j84.8 Z3 - Star Common to Ground: 94 - j50 Even greater imbalance!
Rudy, The #52 mix is readily available in size "240" toroids and makes a useful choke for the higher HF bands. Take a look at the performance of 11 turns on two stacked FT240-52 cores; it's the eleve