[TowerTalk] 80 Meter trap design needed

[Mark - N5OT]

Well THAT is just way too much fun.  I might have to give it a try!  
Been a fan of W7ZOI since I was a teenager.

Back in the 1970s it was "a QRP transmitter and an RF resistance 
bridge."  I'm guessing that is what they had to do before there were 
MFJ-259Bs etc.

Thanks,
73 - Mark N5OT


On 10/23/2021 2:36 PM, Haring family wrote:
> I see Jim Brown weighed in... and it reminded me of something.
>
> I saw a design that Dan, AC6LA, wrote up in his stuff about AutoEZ... 
> about an auto-switching 2-bander. It was originally done by W7ZOI and 
> then some other guys used it and wrote articles.
>
> It was originally used for 2 harmonic bands, but Dan confirmed that he 
> can use it basically on any 2 adjacent bands.
>
> The scheme was to insert an L-network, where the shunt was a cap and 
> the series was an L and C in series. For the low band, the LC was 
> close to series resonant and the shunt had negligible effect. For the 
> high band, the shunt dropped the impedance and the series-series L-C 
> tuned it a little.
>
> Here's a good link with references, even if you don't play with AutoEZ:
> https://ac6la.com/aecollection6.html#64
>
> _*Dual-Band Vertical with "Autopilot" Matching Network*_
>
> Here's a little modeling study which uses both the EZNEC "L Networks" 
> feature and the AutoEZ optimizer in sort of a unique way.
>
> In 1977 Wes Hayward, W7ZOI, described an interesting dual-band 
> matching network. His Hints and Kinks QST submission is reproduced below.
>
> good luck!
>
> Dave N3AC
>
>
>
> On Sat, Oct 23, 2021 at 9:31 AM Mark - N5OT <r-emails at n5ot.com> wrote:
>
>     Thanks Joe, this was just what I was looking for.  I knew someone
>     must
>     have done this before.  I've slept since I last read about the Battle
>     Creek Special.  Legendary skyhook.
>
>     73 - Mark N5OT
>
>     On 10/23/2021 8:16 AM, Joe Subich, W4TV wrote:
>     >
>     > I think there are designs on the old "Battle Creek Special" web
>     pages.
>     > Try: <https://www.pi4cc.nl/link/mkII.php>
>     >
>     > 73,
>     >
>     >    ... Joe, W4TV
>     >
>     >
>     > On 2021-10-23 7:56 AM, Mark - N5OT wrote:
>     >> I hope to make a trap vertical that works on 80 and 160.  I
>     hope to
>     >> find an 80 meter trap design that can handle full power.  The 80
>     >> meter energy would stop when it gets to the trap, but the trap
>     would
>     >> pass 160 meter energy.
>     >>
>     >> It won't be suspended with wire so smallness and
>     lightweightness are
>     >> not necessary criteria.  I hope someone can just shoot me a design
>     >> and values.  Everything I find searching the internet is less
>     >> straightforward than "make a coil like this and stick a
>     capacitor of
>     >> this value here" which I would think would be the easiest way
>     forward.
>     >>
>     >> Any advice?
>     >>
>     >> 73 - Mark N5OT
>     >>
>     >
>
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