[VHFcontesting] MFJ verions of G0KSC LFA's

[Walter Miller, AJ6T]

Zack,

The Cushcraft mounting style that I referred to makes use of a small 
aluminum saddle plus a cylindrical "half-washer" (both with through 
holes) to secure the solid rod elements to the boom using stainless 
steel bolts, lockwashers and nuts.  The elements are not insulated from 
the boom, unlike the original G0KSC design that used insulated tubular 
elements.  I'm sure the element lengths were corrected since G0KSC 
reportedly came to MFJ to model his antennas in this different 
configuration and oversee the redesign.  Cushcraft/MFJ touts this point 
on their webpage. However, some of the photos on the MFJ webpage for my 
antenna (LFA-2M9EL) are incorrect.

73, Walt, AJ6T

On 1/29/2019 7:28 AM, Zack Widup wrote:
> Well, you got me curious, Walt. I'm not sure what Cushcraft mounting style
> is, but are they not insulated from the boom? And the original G0KSC design
> used insulated elements? The lengths of elements will change (increase)
> when going from insulated to non-insulated elements. I have designed (or
> tweaked other designs) and built all the VHF+ Yagis I use and I am really
> familiar with element boom correction factors. I just wonder if the element
> lengths were corrected.
>
> 73, Zack W9SZ
>
>
> On Mon, Jan 28, 2019 at 10:52 PM Walter Miller, AJ6T <aj6t at comcast.net>
> wrote:
>
>> Byron,
>>
>> I have also been intrigued by the LFA Yagi design.  I recently ordered a
>> Cushcraft/MFJ model LFA-2M9EL and I had hoped to get it operational by
>> the January VHF contest.  However, due to construction and tuning
>> problems the antenna is still sitting on the rear deck.  The first
>> problem I ran into was discovering that no hole had been drilled in the
>> boom for the first director. Hmmmm....MFJ quality assurance strikes
>> again.  I had to drill a hole with my hand drill at the specified
>> location.  As you noted, the solid rod elements are mounted "Cushcraft
>> style" to the boom. This is unlike the original G0KSC Innovantennas
>> design that has insulated elements.  I was surprised to discover that
>> the antenna does not have a connector for the coax feed.  You have to
>> make a three-turn coaxial choke balun and connect the flying leads to
>> the screw posts on the loop.  Don't forget to waterproof those exposed
>> leads to prevent water from wicking into the coax.  After all that I was
>> unable to find a smooth resonant point when adjusting the loop size with
>> the antenna pointed skyward.  Now I'm considering making or purchasing a
>> ferrite bead balun to replace the three-turn coaxial choke recommended
>> in the Cushcraft/MFJ manual. I was surprised to discover on the G0KSC
>> website that Innovantennas now offers a bead balun to feed their version
>> of this antenna.  I'll come back to attempt to resonate my LFA-2M9EL
>> when I have time, but for now to say that I am disappointed would be an
>> understatement.  Of course none of this relates to the performance of
>> this antenna once it is tuned up and put on the air.
>>
>> 73, Walt, AJ6T
>>
>> On 1/24/2019 5:50 PM, Byron Tatum wrote:
>>> Hello-   Has anyone used any of the MFJ versions of the 144 or 222 Mhz
>> G0KSC loop fed yagis and would be in a position to provide evaluations of
>> them? I have studied the Innov versions a lot and am very interested in
>> them. I have studied how well they rank in the VE7BQH yagi tables, however
>> I guess the MFJ versions are too new to be included in the tables. I
>> understand that Justin went to MFJ and modeled the LFA's for them using
>> existing MFJ elements and booms (such as on the 13B2 and 17B2) so that new
>> tooling would not be required. I like the 1/4" OD element rods on the Innov
>> antennas. I am a little disappointed in MFJ keeping the 3/16" OD elements
>> but am trying to keep an open mind on this.   Thanks, Byron W5FH
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