I'd like to hear from users of the Force 12 B-1 and B-1/S baluns about their general durability and especially their use for RTTY. I've looked in the archives but don't see a whole lot about them. Fo
Mark, IMO the power dissipated in the Balun will be related to the coax termination impedance at the antenna. If it sees 50 ohms then there will be little current coming back down the shield outer .
Even with a perfect 50 Ohm antenna, there can be significant coax braid current and stress on any balun that is installed! With a perfect 50 Ohm antenna, at the 1500W level the differential-mode feed
I have been running them for about 6 years with no problem on a C4SXL. Many times at full legal on RTTY and in many RTTY contests. Steve KA2KON -- Original Message -- From: "rfman45" <rfman45@hotmail
Even with a perfect 50 Ohm antenna, there can be significant coax braid current and stress on any balun that is installed! With a perfect 50 Ohm antenna, at the 1500W level the differential-mode feed
If the choke is primarily reactive, and the coax braid impedance is also reactive but the opposite sign, adding the choke may *reduce* the net CM path impedance and *increase* the braid current. Maki
Steve has given you the right answer to this. Current squared x resistive ohms = lotsa heat. Not if the current is small enough. And since power is current squared but the current is inversely propo
If the choke is primarily reactive, and the coax braid impedance is also reactive but the opposite sign, adding the choke may *reduce* the net CM path impedance and *increase* the braid current. Maki
Yes, the choke reactance may add to the coax braid reactance producing an increase in the net CM impedance; in fact with certain lengths of coax the braid impedance is high enough that you don't need
All true; and with a well designed ferrite-loaded choke it is exactly the opposite. A common-mode (choking) impedance of several kohms can easily be maintained across a 2:1 frequency ratio. The big a
One reason those folks, which has included me have done that, is because most loaded Yagi-Uda antennas sold by CushCraft and others recommend doing just that in the assembly instructions! [snip] [sni
Okay so how do you route the coax back to the mast from the driven element then? Dangle the coax below the mast? Add another choke at the mast? But wait! The mast is metal too! Just how much of a pro
Oops, I meant dangle the coax below the boom. Chris _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com htt
Below the feedline choke, the outside of the coax is (or should be) almost completely dead to RF, so it can then be taped to the metalwork without further problems. But taping the choke itself onto t
I have built and measured several of the K9YC choke designs with similar results to his. However, you can achieve resistances of several thousand ohms in a less clumsy way. I use the small teflon die
The wood spacer is a good idea, maybe Jim can chime in on how much spacing is needed. This is a real problem with double boom log periodics since both booms are hot with RF, and running the coax alon
Balun Designs is about 30 miles north of me and he made one for me while I watched. The drive was well worth seeing the careful detail and workmanship he puts into his balun's. http://www.balundesign
capacitance between one side of the driven element and the boom. In other words, taping the "choke balun" directly to the boom is making the antenna more UNbalanced! It's amazing to watch people doi
In the past year, I have made and measured (on a network analyzer) seven choke baluns, made of multiple turns (5 to 7) of RG-142 through multiple cores (3 to 5, 2.4" OD) of type 31 material, all depe
capacitance between one side of the driven element and the boom. In other words, taping the "choke balun" directly to the boom is making the antenna more UNbalanced! It's amazing to watch people doin