There are two major changes in Version 2.0! First change is purely mechanical - no enclosure - the choke is not as compact as it is in the original design. It is not a "one-box" device anymore. Before, the enclosure was keeping the coaxial from damage from garden critters and the brittle ferrite rings from mechanical damage. Now, with the open design, one should be more careful while handling/installing the choke. On the bright side - there is one less male-female N connector couple (less loss and less waterproofing) - now the balun has a male and a female connector on each side, oppose to the two female bulk-head connectors on the box. Because the antenna end (/w male N connector) is longer, there is no need for the short Male-to-Male jumper to the antenna. The open construction also allows for better cooling during high-power operation.
The second change is an electrical one - since there is no limit in space, now the choke has more ferrite rings and less coaxial cable turns (2.5 vs 3.5) through the binocular core. This improves the overall impedance! More ferrite rings - more inductance to make up for the lower number of turns. Less turns on the other hand means a decreased capacitive coupling between the turns on higher frequencies. My MFJ-259B is limited in measuring the complex impedance (Z) up to 650 Ohms. The choke was measuring >650 Ohms up to about 20 Mhz. The impedance is around 500 Ohms at 30 Mhz mainly due to the capacitive coupling between the turns. I have installed an additional plastic "jacket" over the coaxial in attempt to increase the space/dielectric between the turns and decrease the capacitive coupling but can't really tell if this has any effect! I am using the same LMR-240 coaxial (RG-8X type with solid center conductor). The choke should be fine for up to 1.5 kW but I am not planing to use it with more than 1 - 1.1 kW (ACOM 1000 amplifier). For steady 1.5 kW use and with antennas with higher SWR I'll recommend a high-temp cable such as RG-142 (silver/teflon).
The new choke takes a little more space but this is not a big deal. I am planing to put extra mechanical support (another stake) for the choke itself.
The second change is an electrical one - since there is no limit in space, now the choke has more ferrite rings and less coaxial cable turns (2.5 vs 3.5) through the binocular core. This improves the overall impedance! More ferrite rings - more inductance to make up for the lower number of turns. Less turns on the other hand means a decreased capacitive coupling between the turns on higher frequencies. My MFJ-259B is limited in measuring the complex impedance (Z) up to 650 Ohms. The choke was measuring >650 Ohms up to about 20 Mhz. The impedance is around 500 Ohms at 30 Mhz mainly due to the capacitive coupling between the turns. I have installed an additional plastic "jacket" over the coaxial in attempt to increase the space/dielectric between the turns and decrease the capacitive coupling but can't really tell if this has any effect! I am using the same LMR-240 coaxial (RG-8X type with solid center conductor). The choke should be fine for up to 1.5 kW but I am not planing to use it with more than 1 - 1.1 kW (ACOM 1000 amplifier). For steady 1.5 kW use and with antennas with higher SWR I'll recommend a high-temp cable such as RG-142 (silver/teflon).
The new choke takes a little more space but this is not a big deal. I am planing to put extra mechanical support (another stake) for the choke itself.
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