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Strange Cobra Antenna

V

VA3WPN

Member
Jan 7, 2012
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Iv picked up an antenna, Center loaded Magmount antenna. Its about 63" in total length. The bottom leg is 11" long, and the top wip is about 48" long. The center load coil is a BIG black egg. Its marked with the cobra lable and snake logo on the center load coil. Its all black, and I can not for the life of me find any information on this.

Im trying to tune it to 27.205.. So that its SWR is lowest in the center of the 11m band. Problem is, that right now, the lowest I can get it is around 28 Mhz. Is this a 10m antenna? or am I just not adjusting properly.
 

did someone trim the whip?
that's the only difference between 10 and 11 meter antennas. that way they can sell to 2 markets instead of one.
 
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If this is a used antenna, then the stinger may have been cut so it could be used on the upper frequency's...

One thing you can do, is check SWR on channel 40 and channel 1...

IF SWR is HIGHER on channel 40, than channel 1, then your stinger is too long and you will need to trim some off...
If SWR is HIGHER on channel 1 than channel 40, then the stinger is too short, and you will need to get a longer one.

Sounds like your probably going to be too short and will need to find a longer stinger.
 
Last edited:
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Iv had the antenna hooked up to a RigExpert AA-520, and the SWR dips to 1.1:1 at roughly 28Mhz. So it needs to be longer. Im just not sure about the adjustment. as the lower leg of the antenna is adjustable too...
 
VA3WPN said:
Iv had the antenna hooked up to a RigExpert AA-520, and the SWR dips to 1.1:1 at roughly 28Mhz. So it needs to be longer. Im just not sure about the adjustment. as the lower leg of the antenna is adjustable too...
Click to expand...
The lower shaft also adjusts? That's different...Doubt it will make a difference tho... Is this a NEW antenna? because it sounds like someone cut some off the stinger. (top section)
 
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No thats not the antenna, Ill take a pic and post it up. The center coil is round like an egg. The bottom shaft is solid, but has locking "collar Nuts" on it, allowing for about 1/2" adjustment on either end. So the length is between 11" and 12". The top is 48" long EXACTLY. Im going to put together a 60" long "stinger" tomorrow at work and see how that helps. The over all length of the antenna is around 68"
 
Haven't seen one like that. But since it has the Cobra logo, it should tune on the 11 Meter band..."IF" it's New, and nothing has been trimmed off the stinger, it's possible it has a ground short either in the connector or where the coax is connected in the mount...I would first try a longer stinger tho before tearing into the mount.
 
I built a 2.5" extention to go between the upper wip and the center load, and it brought the SWR dip down to exactly 27Mhz. This gives me room to tweak it. so somewhere the wip was motified or the antenna was ment for 10m to begin with. I will be hooking the radio up to a frequency counter to see what its outputing on and how much power.

Iv never seen a big EGG antenna like this, and Im glad Im not the only one puzzeled by it.
 

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