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@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
>>
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|