[TowerTalk] TowerTalk Digest, Vol 139, Issue 51

[David Gilbert]

Better gain bandwidth and better F/B bandwidth.  I.e., .... (gain and 
F/B) x (bandwidth).   Possibly I could have written that more clearly.

Marginally less peak forward lobe gain.

Dave   AB7E




On 8/1/2014 10:02 AM, Marsh Stewart wrote:
> "Compared to even a full sized 2 element yagi, a properly engineered Moxon
> will have better gain and F/B bandwidth, considerably higher F/B, a somewhat
> broader front lobe, and only marginally less gain (0.5 db or so)."
>
> So does it "have better gain" or "only marginally less gain"?
>
> Marsh, KA5M
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of David
> Gilbert
> Sent: Friday, August 01, 2014 11:57 AM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] TowerTalk Digest, Vol 139, Issue 51
>
>
> Rick's comment below is spot on ... all of it.   Compared to even a full
> sized 2 element yagi,  a properly engineered Moxon will have better gain
> and F/B bandwidth, considerably higher F/B, a somewhat broader front
> lobe, and only marginally less gain (0.5 db or so). I don't remember how
> front-to-side compares.
>
> Anyone interested should check out the fairly exhaustive work on the
> topic by Cebik (whose books, ironically enough, are periodically
> promoted on this reflector).
>
> 73,
> Dave   AB7E
>
>
>
> On 8/1/2014 9:15 AM, Richard (Rick) Karlquist wrote:
>>
>> On 8/1/2014 8:38 AM, K7LXC--- via TowerTalk wrote:
>>>>    I'm leaning towards buying a Cushcraft XM240 and then modify it
>>>> with  a
>>> Moxon modification as a few of you suggested.
>>>
>>>       Okay, what are the big advantages of a Moxon over a  stock CC 2L
>>> 40?
>>> The CC has 250 kHz of bandwidth and for a given boom length the gain
>>> would be
>>> the same or similar. Please elucidate.
>>>
>>> Cheers,
>>> Steve    K7LXC
>> The 250 kHz of bandwidth is only SWR bandwidth, not gain or F/B, and it
>> is specified at the fairly high SWR of 2:1.  We don't know what the
>> gain or F/B bandwidth is, and the manual recommends one of 3
>> settings:  CW, low phone, or high phone.  That is a red flag.
>>
>> A Moxon, for several reasons, has a greater bandwidth both in terms
>> of gain and SWR, and has a F/B that is unobtainable with an ordinary
>> 2 element Yagi.  It is actually better than a full size 2 element
>> Yagi.  It's the next best thing to a SteppIR.  Actually, it
>> is better than the SteppIR when working large frequency splits (still
>> prevalent in contests), since the bandwidth is instantaneous.
>>
>> It is amazing to me the amount of corporate inertia that must
>> be present to prevent Cushcraft from offering the modified version
>> of their XM240 as an off the shelf product.  The engineering has
>> fallen into their laps.
>>
>> Rick N6RK
>> _______________________________________________
>>
>>
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