[TowerTalk] 80 Meter trap design needed

[WW3S]

my recent 80M trap experience.....my previous 160m ant was an inverted L 
suspended off a hazer on my Rohn 25 tower.....when higher winds or 
storms I cranked the hazer down, so was out of business on 
160M......been looking for an alternative, and one of my other antennas 
is a Hygain Hytower.....most of what I heard about the 160M kit for the 
Hytower wasnt good......I just so happened to have a W2AU 80M trap with 
the ability to mount via tubing......so.....bright idea, I would replace 
the stinger on my Hytower with different size tubing, allowing me to 
mount the trap on top of the hytower, and attach a loading wire to 
it.....I had most of the tubing I needed, ordered what few pieces I 
needed....I built the new stinger to the length of the old one (probably 
my first mistake), attached the trap, and about 47 ft of wire (per the 
instructions from Unadilla for a wire antenna)......tilted the tower 
back up, swr was a little higher than before on 80M, but was less than 
1.5:1 at 1820 so I left it.......worked a few stations on 160, worked a 
few on 80, everything seemed good......until........until I tried to 
work S9OK on 160M.....with the amp.....at about 1400 watts.....calling 
for about an hour and them something went south in a hurry.....swr all 
over the place on 160 and 80.....I havent had the chance to tilt it back 
over but I suspect the trap overheated.......another bright idea that 
wasnt so bright after all.....

------ Original Message ------
From: "Jim Brown" <jim at audiosystemsgroup.com>
To: towertalk at contesting.com
Sent: 10/23/2021 2:54:20 PM
Subject: Re: [TowerTalk] 80 Meter trap design needed

>On 10/23/2021 4:56 AM, Mark - N5OT wrote:
>>I hope to make a trap vertical that works on 80 and 160.
>
>First question is, why a trap? If it's not height, consider a fan.
>
>Second, there's a design for 2-band 2nd harmonic dipoles where there's a loading coil (NOT a trap) near what would be the quarter-wave point of the lower frequency band, with a relatively short wire beyond it. That design has relatively narrow SWR bandwidth on the lower frequency band, but bandwidth comparable to dipole on the higher band.
>
>This design works quite well, and there have been several successful commercial implementations of it. Hypower Antenna Company (tiny ad in QST) sells them, and may sell the loading coils separately. I measured their coils for the 160/80 and 80/40 designs many years ago, and can probably find the data. But it's a fairly easy design to do in NEC, and I recently did one for a 40/20 dipole made from Al tubing for use on CQP county expeditions.
>
>73, Jim K9YC
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