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Phone: 760-747-3343 FAX: 760-747-3346 Mail: PO Box 462222 Escondido CA 92046 e-mail Info@ Palomar- Engineers.com |
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PPalomar® Engineers |
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Model BA-4-1500 Kit |
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Purpose. This kit is designed to convert from coaxial cable to ladder line at full legal power at 100% duty cycle from 1.8 to 30 MHz. It provides conversion from unbalanced coax to balanced ladder line and gives a 4:1 impedance step-up to reduce SWR on the coax. |
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Application. A dipole can be used as a multi-band antenna by using a tuner to convert the impedance to 50 ohms for the transmitter. On its fundamental the dipole impedance will be about 75 ohms. But on its second harmonic its impedance will be on the order of 3500 ohms. If 50 ohm coax is connected directly the SWR on the fundmental will be 1.5 but on the second harmonic it will be 70. The 4:1 balun changes these to 2.7 on the fundamental and 17.5 on the harmonic. A 9:1 balun would be even better but it is very difficult and expensive to build with adequate bandwidth that will stand up to this service. 4:1 is the best compromise for performance and cost. Of course the ladder line changes the impedance seen at the balun depending on its length. But there still is a wide range of impedances seen from band to band and a very rugged balun is required to cope with it. |
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Model BA-4-1500. Kit consists of two type T200A cores, two colors of #14 teflon insulated wire, a SO-239 UHF connector with stainless steel ground lug hardware, and winding instructions. Operate open or in a case of your choice. It is for use from 160 through 10 meters at full legal power at most impedances encountered. |
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Model BA-4-1500................$32.50 |
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+ $8 S&H. Tax in Calif. |
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Note: $8 S&H is “per order”. Order more than one and S&H is still $8. |
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www.Palomar-Engineers.com Updated 4-28-08 |
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