What I do is connect the choke across the output of a tuner to generate a CM signal across the winding. Adjust the tuner for a good match to 50 Ohms and drive it from a transmitter. That way you have
Jim, I worried that the choke impedance might be too high to be matched by the tuner, but my TenTec 238 matches that Type 52 choke easily from 7MHz thru 30MHz, including resonance where its impedance
Do the maths on saturation - you'll find that core overheating occurs well before saturation for the duty-cycles typical of Ham operation. To quote Amidon: "Overheating of the core will usually take
Note what I said about duty cycles! Steve G3TXQ To quote Amidon: "Overheating of the core will usually take place long before saturation in most applications above 100kHz." Steve G3TXQ This generaliz
Hans, The key qualifier is that the **matched** loss of the combined pair is equal to the **matched** loss of the individual coaxes! The trick is that Zo has changed between the individual case and t
You can also measure loss using a single-port analyser. The underpinning maths is here: http://www.karinya.net/g3txq/wet_ll/tl_formulas.pdf Steve G3TXQ On 06/08/2016 07:03, Richard (Rick) Karlquist w
With a short circuit termination, the line needs to be an even number of quarter-waves long; with an open termination the line needs to be an odd number of quarter-waves long. For the short-circuit t
Some of the accuracy issues can be explored using Dan's excellent TLD software. Say we had 150ft of Belden 9201 which we were trying to characterise for loss on 160m; TLD predicts a matched loss of 0
Steve, Firstly your figures are out for the 50 Ohm system; the figures are 273.9V and 5.5A Once the SWR is no longer 1:1, there is an infinite range of impedances for any particular SWR, and therefor
Steve, Those were rms figures of course; if you need peak values, multiply by 1.414 Steve G3TXQ Firstly your figures are out for the 50 Ohm system; the figures are 273.9V and 5.5A Once the SWR is no
You need to define what you mean by "ring". The antenna will see a conjugate match at 1.85MHz (not 2.24MHz) looking back towards the station end, but I don't know if that's what you mean by "ring"? S
Mike, This member of the "TT community" says that, if you parallel connect the two lengths - outer to outer, and centre to centre, at each end - you'll have a 25 Ohm line with _the exact same_ matche
It's worth remembering that the equations involve _vector_ sums. So just because the current _amplitudes_ in the two legs of a TL might be equal in the two directions, it doesn't mean they are balanc
Bill, I use a very similar antenna system. I measure best feedline current balance when I use an unbalanced tuner (Ten Tec 238) connected through a very short length of RG213 to a 1:1 CM choke mounte
Maximo, I don't think that instrument will allow you to see the Zcm of a choke directly on-screen. However, it looks like it will display |S21| directly. With the choke connected between the two port
Maximo, A test I use to assess the capacitance added by the test jig is as follows: Wind a high-Q air-cored coil and connect a small-value parallel capacitor across it. Measure its resonant frequency
Wes, Thanks, I hadn't spotted that one! Steve G3TXQ On 03/01/2018 19:40, Wes Stewart wrote: On 1/1/2018 3:00 AM, Steve Hunt wrote: ... The problem is that models picturing capacitance between adjacen
For completeness, here's the data referred to by G3RBJ in his paper: http://www.g3ynh.info/zdocs/magnetics/appendix/Toroid_selfC.html Notice how the self-capacitance falls as the number of turns incr
Hi Paul, No, I no longer use the 50 Ohm termination at the jig. I originally included it because I was using long RG174 patch leads between the VNA and the jig and wanted to minimise coax loss at the
Measuring high-Z chokes accurately is challenging, and it's easy to become obsessive about this stuff. I know because I'm probably one of the worst offenders :) But then I ask myself:: if an uncompen