Author Topic: All band no tuner needed antenna (This is and endfed antenna)  (Read 8132 times)

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jdh

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Re: All band no tuner needed antenna (This is and endfed antenna)
« Reply #15 on: October 27, 2014, 02:58:12 PM »
Vertical half rhombic is directional.  You have to take that into consideration when setting it up.

RE: terminating resistor

get two sections of PC board, clamp them together, then drill 222 evenly spaced holes through the two boards.  Get 222 100k Ohm 1/2 resistor of your choice of construction.  use the resisters as the meat in the sandwich, put the leads through the board with the foil side out then solder all the leads to the top board, trim the leads, turn the assembly over and repeat.  You now have a 450 ohm 110 watt resistor.  If you shop wisely of have a well stocked junk box the resistor should set you back less than $30.

spacecase0

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Re: All band no tuner needed antenna (This is and endfed antenna)
« Reply #16 on: October 27, 2014, 08:26:28 PM »
I know someone that did a similar thing to make a 50 ohm dummy load,
it worked for about 5 years and then stopped working so well, it was kept inside in good conditions,
so no idea what made it quit working, it all looked just fine when looking in the sides, and it was never overloaded,
and it looked quite hard to take a part and fix,

anyone know what may have gone wrong ?
do others have things like that work well for a long time ?

Lamewolf

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Re: All band no tuner needed antenna (This is and endfed antenna)
« Reply #17 on: October 29, 2014, 06:29:00 AM »
Vertical half rhombic is directional.  You have to take that into consideration when setting it up.

RE: terminating resistor

get two sections of PC board, clamp them together, then drill 222 evenly spaced holes through the two boards.  Get 222 100k Ohm 1/2 resistor of your choice of construction.  use the resisters as the meat in the sandwich, put the leads through the board with the foil side out then solder all the leads to the top board, trim the leads, turn the assembly over and repeat.  You now have a 450 ohm 110 watt resistor.  If you shop wisely of have a well stocked junk box the resistor should set you back less than $30.

For SSB & CW work the resistor only needs to be rated at half power of the transmitter.  Therefor I ordered a 50 ohm/50 watt non inductive resistor from Mouser Electronics that cost about 12 bucks when you factor in shipping.  The resistor comes in a TO220 style case so it cab be bolted to a heat sink which I do recommend doing.  I used a 50 ohm resistor because I'm feeding it with a 9:1 balun to convert it to 450 ohms and that way you can swap ends with the resistor and the antenna feed point to change its direction of radiation.  You can do this manually or through the use of a relay switchbox.  But whatever end the resistor is connected to will be the direction of maximum radiation.

Captain Crunch

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Re: All band no tuner needed antenna (This is and endfed antenna)
« Reply #18 on: October 29, 2014, 08:52:35 PM »
At $479 I think I'll pass on the Chameleon !  I only have about $25 in mine and it works great........

If you can build the same thing for $25 then good for you! I do not have a large junk box to experiment so I've to buy everything brand new all the time  >:(  On their Google + page Chameleon Antenna are talking about a new no tuner terminated antenna that they'll sell for about $99:

https://plus.google.com/+ChameleonAntennaOfficial/posts/5VnD8uUVhW7

I don't know how the antenna will be installed and/or what are the requirements to get it to work but the SWR curve looks very good:



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Lamewolf

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Re: All band no tuner needed antenna (This is and endfed antenna)
« Reply #19 on: October 30, 2014, 06:18:54 AM »
If you can build the same thing for $25 then good for you! I do not have a large junk box to experiment so I've to buy everything brand new all the time  >:(  On their Google + page Chameleon Antenna are talking about a new no tuner terminated antenna that they'll sell for about $99:

https://plus.google.com/+ChameleonAntennaOfficial/posts/5VnD8uUVhW7

I don't know how the antenna will be installed and/or what are the requirements to get it to work but the SWR curve looks very good:



That's good and probably something like what I built, but looking at the swr curve, I think mine has it beat because its pretty flat from 160 to 10 meters with the exception of 30 meters where its around 2.5:1 for some reason.  Don't know if its the wire length I used or maybe the environment I had it setup in but my LDG Z11 Pro2 tuner would handle it with no problems if I needed 30 meters.

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