I use a 4229 Tuner that I put together many years ago. Part of the build process was winding a balun for the twinlead input of the tuner. Being a ham means being unable to leave well enough alone. I
I have taken standard Tee tuners with the common voltage balun of the 70's and instead, hooked up a short coax to their coax output connector. I run that to a Van Gorden Current balun, and I think it
Loss in ferrite chokes and in baluns wound with ferrites is NOT a function of HEAVY construction, but depends primarily on the characteristics of the ferrite material (the MIX), how the chokes are wo
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sat, 13 Nov 2010 18:23:18 -0600
The LF end of the useful range depends on the raw inductance of the winding which comes from the magnetic material and the turns. The first stop band going up is when the length of the wire (loaded b
Jerry, we all prefer a link coupler tuner. Unfortunately there are no commercial units available anymore, at least not in the amateur radio market. Most of the old Johnson Viking matchboxes on the ma
Question: How does the internal balun in a link coupled tuner compare with the a 'tri-filer' balun such as used in the Nye-Viking MB-V-A? Thanks, 73 de Phil - N8PS -- ________________________________
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sat, 13 Nov 2010 20:43:13 -0600
There is NONE. The output coil is balanced to ground, as are the capacitors, which in my link coupled tuner can be switched from parallel for high impedance loads to series for low impedance loads. T
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sat, 13 Nov 2010 21:09:40 -0600
True for their tuning range. It never was great and hasn't included WARC bands ever. Maybe I'm an old pack rat and should put a few things up for sale, but the last tuner I built (wasn't balanced) I
A link coupled tuner IS a balun. It is not a tuner WITH a balun. It is essentially a tunable air core transformer. Usually (perhaps always) a link coil of just a few turns is the primary of the tran
Of course, the Johnson Matchbox has its secondary capacitors "centre-tapped" to ground; that makes it a "stiff" voltage source. In other words it's a VOLTAGE balun, just like the 4:1 Ruthroff found a
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 14 Nov 2010 11:48:55 -0600
Sometimes we want to FORCE that voltage balance, sometimes we just want to limit feed line shield current on the outside of the line. A home built tuner need not have the secondary capacitors or coil
I think a "very fine hair" is being split here. When this "hair" is measured in dB units instead of linear units the loses become insignificant. While yes the old balanced match boxes are technically
If that's a problem I would prefer to use a couple of high value resistors to leak the charge to ground, rather than compromise the current balance on the TL. Steve G3TXQ ____________________________
It has long been W7EL's contention that you CANNOT force balance in an antenna system by forcing voltage balance on the line, and I firmly agree with him. Balance in ANY circuit is defined by the bal
I certainly agree with respect to loss, but the linear view is important from a dissipation point of view. I do a lot of measurements, mostly to understand and characterize some physical elements or
Jim, I agree! I've been doing some balance measurements on a 100ft doublet I have fed with ladderline. Because of its local environment it's a pretty unbalanced antenna system. I measured ladderline
In my experience, all those harmless fractions of a dB have a nasty habit of getting together and adding up to something more substantial ;) Steve G3TXQ ______________________________________________
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 14 Nov 2010 12:52:35 -0600
But some tuners have shown less than 10% efficiency at the tuning extremes, usually doing a large impedance transformation at 160 meters. That's 10 dB loss, and even at 100 watts it leads to smoked t
Jerry, I must challenge you again on that statement - it simply isn't true of a 1:1 Current Balun at the output of a tuner. The core flux of that Balun - and therefore its loss - is determined by the
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 14 Nov 2010 13:11:42 -0600
Its really difficult to have a wire antenna that is truly balanced. One end nearly always has a different exposure to dielectric and grounded objects than the other leading to differing capacitance t