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6m and 10m inv V calc
I question my calculations for a inverted-V dipole length for 50150 and
28400 into a 4:1 balun. I think they came out too short for 200ohms center Z Can someone confirm my two calculations? Thank you! |
#2
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6m and 10m inv V calc
Pete wrote:
I question my calculations for a inverted-V dipole length for 50150 and 28400 into a 4:1 balun. I think they came out too short for 200ohms center Z Can someone confirm my two calculations? Thank you! Why don't you download the free EZNEC demo, which will do an inverted-V, and see what it says? http://www.eznec.com/demoinfo.htm -- Jim Pennino Remove .spam.sux to reply. |
#3
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6m and 10m inv V calc
Ralph Mowery wrote:
Why are you using a 4:1 balun with a dipole ? If it is a simple dipole with only one wire in each direction instead of a folded dipole the impedance is around 70 ohms. If you decide on a balun it should be a 1:1. When adjusted for the lowest swr you may find that 1.4 to 1 is about as low as it will go if you use a 50 ohm coax. "Pete" wrote in message ... I question my calculations for a inverted-V dipole length for 50150 and 28400 into a 4:1 balun. I think they came out too short for 200ohms center Z Can someone confirm my two calculations? Thank you! With a V, you can get the feedpoint impedance right to 50 ohms.. somewhere around 120 degrees included angle |
#4
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6m and 10m inv V calc
Why are you using a 4:1 balun with a dipole ? If it is a simple dipole with
only one wire in each direction instead of a folded dipole the impedance is around 70 ohms. If you decide on a balun it should be a 1:1. When adjusted for the lowest swr you may find that 1.4 to 1 is about as low as it will go if you use a 50 ohm coax. "Pete" wrote in message ... I question my calculations for a inverted-V dipole length for 50150 and 28400 into a 4:1 balun. I think they came out too short for 200ohms center Z Can someone confirm my two calculations? Thank you! |
#5
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6m and 10m inv V calc
"Jim Lux" wrote in message
... Ralph Mowery wrote: Why are you using a 4:1 balun with a dipole ? If it is a simple dipole with only one wire in each direction instead of a folded dipole the impedance is around 70 ohms. If you decide on a balun it should be a 1:1. When adjusted for the lowest swr you may find that 1.4 to 1 is about as low as it will go if you use a 50 ohm coax. "Pete" wrote in message ... I question my calculations for a inverted-V dipole length for 50150 and 28400 into a 4:1 balun. I think they came out too short for 200ohms center Z Can someone confirm my two calculations? Thank you! With a V, you can get the feedpoint impedance right to 50 ohms.. somewhere around 120 degrees included angle Dittos. Radiates equally poorly in all directions though A rotatable dipole or 2 el beam would be a simple project. |
#6
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6m and 10m inv V calc
JB wrote:
"Jim Lux" wrote in message ... Ralph Mowery wrote: Why are you using a 4:1 balun with a dipole ? If it is a simple dipole with only one wire in each direction instead of a folded dipole the impedance is around 70 ohms. If you decide on a balun it should be a 1:1. When adjusted for the lowest swr you may find that 1.4 to 1 is about as low as it will go if you use a 50 ohm coax. "Pete" wrote in message ... I question my calculations for a inverted-V dipole length for 50150 and 28400 into a 4:1 balun. I think they came out too short for 200ohms center Z Can someone confirm my two calculations? Thank you! With a V, you can get the feedpoint impedance right to 50 ohms.. somewhere around 120 degrees included angle Dittos. Radiates equally poorly in all directions though A rotatable dipole or 2 el beam would be a simple project. Nonsense. The difference in broadside gain between a dipole and an inverted V is about 0.5 db. -- Jim Pennino Remove .spam.sux to reply. |
#7
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6m and 10m inv V calc
JB wrote:
"Jim Lux" wrote in message ... Ralph Mowery wrote: Why are you using a 4:1 balun with a dipole ? If it is a simple dipole with only one wire in each direction instead of a folded dipole the impedance is around 70 ohms. If you decide on a balun it should be a 1:1. When adjusted for the lowest swr you may find that 1.4 to 1 is about as low as it will go if you use a 50 ohm coax. "Pete" wrote in message ... I question my calculations for a inverted-V dipole length for 50150 and 28400 into a 4:1 balun. I think they came out too short for 200ohms center Z Can someone confirm my two calculations? Thank you! With a V, you can get the feedpoint impedance right to 50 ohms.. somewhere around 120 degrees included angle Dittos. Radiates equally poorly in all directions though The pattern from a inverted V with 120 degree included angle (30 degree droop from horizontal) is almost the same as a horizontal dipole at the same height. If the apex of the V is about 1/3 of the droop distance higher than the dipole, the "ground reflection" component is about the same. For the 10m example here, the dipole is 5m long, roughly. A 30 degree droop is about a meter on the 2.5 meter leg on the dipole. (e.g. sin 30 is 0.5), so putting the dipole a foot higher (30cm) will give you almost the same pattern as a horizontal dipole. A rotatable dipole or 2 el beam would be a simple project. given the complexity of rotators in general, rigging up two crossed dipoles and a switch might be a better solution. |
#8
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6m and 10m inv V calc
On Jun 10, 11:15*am, Jim Lux wrote:
given the complexity of rotators in general, rigging up two crossed dipoles and a switch might be a better solution. Don't even need the switch.. Just feed the crossed dipoles with a single coax line and off to the races. |
#9
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6m and 10m inv V calc
wrote in message
... On Jun 10, 11:15 am, Jim Lux wrote: given the complexity of rotators in general, rigging up two crossed dipoles and a switch might be a better solution. Don't even need the switch.. Just feed the crossed dipoles with a single coax line and off to the races. Truly. I just hung 40m from 80m wire with some spreaders. If I had more wire I would add a couple more at 80m just for bandwidth. I doubt that 6 and 10 meter cause any interaction with a common feed. At that size a rotatable dipole is easily made with mobile whips. A rotatable dipole takes advantage of the deep nulls. A dipole with 120 degrees included angle is just a droopy dipole. An inverted V with 90 degrees included angle or less has a combination of vertical and horizontal components to its radiation and is more omnidirectional. More so with a metal supporting mast. |
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