Getting ready to install another 6M yagi here and building another for a friend. Want to use a choke on the feed line which will be either RG-213 (MIL-C-17 compliant) or on LMR-400UF (super flex). In
That is a 43 mix and a good choice; that is what I use on my 6M yagis. Six to eight is adequate. Carl KM1H _______________________________________________ ____________________________________________
You can also use a larger diameter toroid and run multiple turns of your coax through it. The inductance of the choke goes as the square of the number of turns, so 5 turns through one core is like 25
This approach is good on HF, but on 6 meters, with RG213, the trouble is that the minimum bend radius of the RG213 coax forces rather large loops. When the total length of coax is too long in terms o
It aint easy getting 5 turns of RG-213 thru a 2.4" OD dia toroid! The definitve tests for Fairite 43 Mix beads as a sleeve balun was done in the early 80's and published in Scuttlebut and most likely
It doesn't matter -- it's RESISTANCE we want, not inductance. But 6 meters IS a challenge for a choke balun (it's also quite a challenge to measure). As Jim Lux suggested, a multi-turn choke WILL wor
I've used RG142 which is Teflon insulated for high power use but still small in diameter (like rg58). I find that cutting the jacket off allows it to bend enough to fit a 2.4 in toroid pretty easily.
On higher HF and 6M simply winding all the turns in one direction adds a lot of capacitance which defeats the effectiveness. Using RG-142 or RG-303 has been popular for decades on these toroids. Wind
Good point, and that's probably why the measured data shows less improvement for the higher frequencies (as well as the other issues). That's the great thing about (the other) Jim's paper, he has all
not all that tough. I've got one sitting here in front of me. Don't do it outside on a cold day, though. Jim Brown's paper has very high quality measurements done with traceably calibrated lab gear (
I wonder if this can be quantified.. Say you have two pieces of coax side by side that are 1 meter long (about 1 foot loop diameter). Say the spacing is twice the thickness of the jacket.. call it 2
Yes, but resistance doesn't go up as N squared either. Rick N6RK _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@cont
Capacitance between turns always exists, which is what creates the large peak in common-mode impedance at resonance. This is particularly desirable for a monoband antenna because the peak can be plac
By going from the conventional to the crossover method I was able to get a G5RV to cooperate that I was using at the summer cottage decades ago. No amount of twidling of the conventional turns worked
My shop currently has a 8757A, 8753B and an assortment of SA's, sig gens, sweeper, NF meter, cal sets, etc. Older technology but more than adequate for my needs. Plus they show up at rather distress
That can easily happen, as the equivalent lumped capacitance is only a few pF so the resonant frequency is extremely sensitive to small variations in strays. Even a twisted-wire 'gimmick' capacitor c
Yes. I've devised a method of winding transmitting baluns using coax the size of RG8 and RG8X that minimizes the stray capacitance and results in multi-turn chokes that have relatively high choking i
Until the 8510 breaks, since Agilent doesn't support them anymore, even for repairs. (I have an 8510C in the lab here at work, and it has a strange lockup problem...) More power to them. They can put
Until someone comes out with a VNA that does excellent work thru 24GHz for $1000 I'll have to rely on the old workhorse. Im very familiar with the 8510, used it and the other models I have for many