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Author Topic: Rex Bassett Helium Trap Antenna  (Read 968 times)
W4PBU
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Posts: 86




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« on: February 18, 2006, 03:30:01 PM »

I inherited a dipole type antenna.
The trap at the feedpoint is marked as follows
Rex Bassett Helium Trap Antenna.
Model # ?ox 4163
Made by Rex Bassett Electronics
Ft Lauderdale, FL
I can not find anything on them using Google or any other search engine.
Does anybody know anything about these antennas.
The traps or baluns at the end of the antenna are unmarked.
Any help would be greatly appreciated.
Thanks
Dave W4PBU
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N6AJR
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Posts: 9914




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« Reply #1 on: February 18, 2006, 09:08:17 PM »

can you stick it up on a temporary setup and run the mfj 259 on it to see where it  likes it..
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K7KBN
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Posts: 2785




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« Reply #2 on: February 18, 2006, 09:45:43 PM »

I Googled up a "Rex Bassett Inc." in Ft. Lauderdale FL.  Appears to have been a crystal dealer and radio equipment builder/seller.  Didn't pick deep enough to figure out the time frame, but nothing about antennas in the little searching I did.
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73
Pat K7KBN
CWO4 USNR Ret.
K7UNZ
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Posts: 691




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« Reply #3 on: February 19, 2006, 11:13:22 AM »

Dave, let's get the mental picture of this antenna....

You say there is a "trap" at the feedpoint, and some "traps/baluns" at the END of the antenna.

If there is some fixture at the feedpoint, it is most likely a "balun".  Might be 1:1, 4:1, 10:1, almost anything on the older dipoles.

Now about the stuff on the end of the antenna.  Are they really at (or close to) the ends of the wire?  If so, then they most likely are loading coils, not really traps.  Commom practice to shorten a 160 or 80 meter diploe to fit into places too small for a full size dipole.

So, measure the length of the wire from the center (feed point) to the inner end of the loading coil.  Then measure the length of the same wire from center to outter end of the wire.

If there are no other "traps" in the antenna, the length should give you a good idea of what band it was designed to operate on.  

As for the "helium", it's most likely long gone.  At one time it was considered "state-of-the-art" to fill traps, loading coils, etc., with inert gas to protest from weather, and stabilize operation.

But judging from your description, it's an "oldie" for sure....

73, Jim/k7unz
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KA0GKT
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Posts: 555




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« Reply #4 on: February 19, 2006, 04:18:33 PM »

I kind of remember the "Helium" balun advertised in one amateur magazine or another.  Helium doesn't hold water vapor, so the inside of the balun (in theory) doesn't have water problems.  The same could be done with a nitrogen or other gas fill at less cost, helium just sounds exotic IM (Not So) HO.  I don't think that there is much difference dielectrically between He and air as to make one better than the other.

73 DE KAØGKT/7

--Steve
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WB2WIK
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Posts: 20574




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« Reply #5 on: February 20, 2006, 09:10:14 AM »

Helium's actually silly as it's the second smallest molecular size and very, very difficult to hermetically seal except with speciality glass or ceramic bonded to specialty metals.  You might note that no kind of "helium" balloon can contain helium for very long.  I doubt those traps or baluns still have any helium in them.  Cute hype, though.

(As a side note: In high school, I remember we filled some footballs and basketballs with helium.  It didn't stay in there very long in either case, but at least for a little while, it was easy to throw those balls *very* far.)

I do remember the Rex Bassett Company quite well, though.  It's been a long time.  The advice about pulling the antenna up above ground and checking resonance with an antenna analyzer was pretty good.  You can guess the resonant frequency of the dipole between the first set of traps, as it should be a normal half-wave on some band.

WB2WIK/6
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