[TowerTalk] M2 40M2L

[W2RU - Bud Hippisley]

I live in the Adirondack Mountains of upstate NY, with weather fairly similar to central NH.  I own both a 40-2CD (predecessor to the XM240) and an M2 40M2LL (linear loaded elements).  In the past, I've owned a Mosley S-402 (discrete loading coils at the element centers), a Hy-Gain (can't remember the model #, but it had linear loading, as well), and full-size 2-element and 4-element 40-meter monobanders.

I believe the M2 shorty 40 is mechanically far superior to the 40-2CD.  So much so, I would far sooner have that 40-meter antenna at the top of my tower than any of the others I've used.  Electrically it is not superior, however, because ice and snow will cause the frequency of minimum SWR to move more than 50 kHz.  I can't say for sure how far, since my "dry weather" minimum SWR frequency is 7.050, and sometimes in the winter it drops below 7.000.  Most of the year I was unable to run legal limit with my Alpha 99 because the reflected power protection circuit would kick it off the air on the low end of the band, but there have been times during the winter months when accumulated ice allowed me to get back to 1500 watts.

It is my OPINION, based on rather rudimentary and not always consistent S-meter measurements of received signal strengths while rotating the 40M2LL, that the "dry weather" forward gain of my 2-element array disappears by the bottom of the band (with the beam assembled with the 7.050 dimensions).  Next time I take it down, I'll make some element changes to move the sweet spot on the forward gain curve down 25 kHz or so, but I have some serious EZNEC modeling work to do first.

Despite its mechanical limitations, my 25-year-old 40-2CD was a phenomenal performer year-round until about four years ago, when a massive October ice storm broke it into smaller parts.  That's when I switched to the M2.  If I ever get any spare time one of these years, I'll finish rebuilding the 40-2CD with the W6NL strengthening mods so I can put it back up.  One can never have enough aluminum up in the air.

I'm not familiar enough with the XM240 to know if it has any strengthened members a la W6NL, but if that's the direction you choose, I'd make sure it does or I'd add some before putting it up.  Ice storms are no stranger to your part of the country!

Bud, W2RU


On Nov 9, 2010, at 10:11 AM, Shane Mattson-->K1ZR wrote:

> Any M2 shorty 40 owners out there?  I'm soliciting your feedback on the
> performance/construction/maintenance etc as I'm considering purchasing this
> antenna.  Any comparisons to the Cushcraft XM240 would be helpful as well.
> My plan is to install a 2EL 40 at 100' on a hilltop in southern NH in a
> high-wind zone.
> 
> TNX.
> 
> -Shane K1ZR