Hi Tim,
thanks for checking in. I will be calling your guys to inquire about the Yagi
Mechanical program soon. I don’t know if you have been following my ramblings,
but I have plans to make two Moxon 40M yagis out one Telrex 6M46 I have in the
barn. I’m in the process of putting my 200 ft rotating Rohn 55 back up. I
took it down to move the rotator to 5 ft above ground and will put the tower
back up to 155. I plan to put the Moxons at 70 and 140 feet. I’m looking to
do some take off angle analysis because I am on a ridge well above average
terrain and I think the 140/70 arrangement may work more like a higher array,
but I don’t know.
73,
Dave, K4TO
> On Jul 27, 2017, at 11:40 AM, Tim Duffy <k3lr@k3lr.com> wrote:
>
> I have had a stack of two W6NL 40 meter two element Moxon's up for nine
> years. They are converted from Cushcraft XM-240s. Mounted at 185 ft over 120
> ft - both on Ring Rotors.
>
> The modeled results that W8WWV provides in his summary document (URL
> attached) shows the predicted parameters of the Moxon's at K3LR and they are
> pretty much working as per Greg's analysis.
>
> http://www.k3lr.com/engineering/
>
> I continue to be amazed at how good the performance of the W6NL Moxon's is
> when compared to a three high stack of full size four element OWAs that are
> on another tower about 1000 feet away. Sure the big three high stack is
> better - but the Moxon's sure hang tough.
>
> We are also using a monoband stack switch (mounted at the center of the
> array) to allow selection (and matching) of either Moxon, both in phase or
> both out of phase.
>
> 73
> Tim K3LR
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
> StellarCAT
> Sent: Thursday, July 27, 2017 7:53 AM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Modeling the Moxon
>
> Dave's original statement was "can someone model 2 40 meter yagis stacked?"
> .... at the time the discussion was about stacks - then got in to the
> relative performance of 40 meter stacks ... my intent was/is to do just that
>
> ... 2 x 2 element yagis will serve the purpose. If modeling the interaction
> of the 40 on say a 15 (it won't interact noticeably with a 20) then I can
> attempt a Moxon. Note I have modeled a Moxon before with results that seem
> correct ...using NEC2.
>
> Regarding 40 meter stacks ... when I model 2 x 2 element yagis at 140/70 the
>
> increase in gain is only about 1.4db ... which was my original point that
> there isn't a great deal gained from stacking on 40 meters other than the
> change in angle (which again the lowest one will seldom be the better choice
>
> over the stack) and if available having the ability to go 2 different
> directions... extending that to 2 4 element antennas the increase in gain is
>
> even less - less than 1 db. My original comment was you need to get 40's up
> higher and further apart to start to get a bit more gain increase. (that
> stated even with 20's stacked the increase in gain when stacked "properly"
> is 'only' about 2.4 db or so).
>
> Gary
>
>
> -----Original Message-----
> From: Joe Subich, W4TV
> Sent: Wednesday, July 26, 2017 8:00 PM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Modeling the Moxon
>
>
> If you intend to model a Moxon, particularly the Leeson Moxon, you will
> need software that uses the NEC4 engine.
>
> NEC2, commonly used in amateur software because it is free, does not
> handle right angle connections and tapered elements correctly.
> Numerical corrections have been developed for the taper issues
> (primarily by Leeson) but NEC2 still does not handle elements that
> are not parallel very well.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 7/26/2017 6:28 PM, Dave Sublette wrote:
>> I have spent a fair amount of time reading a few of the Moxon construction
>
>> articles about the modified Moxon for 40 meters. I have a spare 6 element
>
>> 20 meter Telrex monobander for 20 meters in my barn. Doing some
>> scratching on paper, it looks like I could build two, two element Moxons
>> for 40 using the material in that yagi. I would need to buy the tubing
>> necessary to build the Tee sections on the end.
>>
>> Since all of the element diameters and taper schedules would be different,
>
>> I should model it. I have the Antenna Model Software package. I haven't
>> used it much. I haven't modeled antennas in over 15 years. I used to use
>> K6STI software when I did and I loved it. Some of the articles I have
>> read say good things about the Antenna Model program. I am wondering if
>> that would be good enough to use on the Moxon.
>>
>> Now I know the Moxon doesn't model well. The W6NL version is the standard
>> and the best advice is to build it like that. But I have all this
>> beautiful aluminum that I don't want to waste. Plus, the 3 1/2 inch boom
>> on the T-rex is really stout enough to handle this antenna. At least one
>> article says they wish they had used a larger boom diameter.
>>
>> I suppose a good plan would be to model the W6NL and then my version on
>> the same software and adjust my version until the results matched those
>> obtained with the W6NL. The question is .. Is the Antenna Model package
>> adequate for the job?
>>
>> A really good answer would be that someone has already modeled the W6NL on
>
>> Antenna Model and would share the file with me. :-)
>>
>> Thanks,
>>
>> Dave, K4TO
>> _______________________________________________
>>
>>
>>
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