[amsat-bb] M2 LEOpack tuning

[Mark L. Hammond]

Hello Mark,

A couple of years ago I had isssues with an M2 2M7 antenna.  SWR would go high, come back down.  Went on for months, up and down the latter, trying to fix. Drove me nuts.  I finally ordered a replacement antenna and swapped out the driven element.   Turns out the issue was this--poor connection between the driven element aluminum "block" and the center pipe!!   After cleaning up the (not visible) corrosion on the underside, where it sits on the center pipe, it was fine.    I swore it was a matching cable, broken solder joint down in the driven element, coax connector...but it wasn't.  All due to bad contact/corrosion between driven element block and main aluminum center pole.   

Might not be your problem--but something to check and remember in case that's a culprit later!

I've had numerous M2 antennas over the years.  Love them, highly recommend.  They are tough, durable, and effective. 

Let us know when you figure out...even if it's in a few years ;-)

73,

Mark N8MH 

At 07:57 AM 4/5/2020 -0500, Mark D. Johns via AMSAT-BB wrote:
>I’ve had my LEOpack antennas about 8 years, but over the winter my station became almost totally deaf on 2 meters. I took the 2 meter beam down and cleaned up a bunch of corrosion around the coax connector, and that seems to have helped the situation, but... I checked the antenna with my MFJ Antenna Analyzer (which I did not have back when I first assembled these antennas) and find that the 2 meter beam is resonant at about 143.95 MHz — just beloww the 2 meter ham band. Up at 145.9, where I would LIKE it to be resonant, my SWR is about 2.5:1. Pretty high. Messing with the tuning sliders only made things worse (these adjust impedance and not necessarily resonance), so I’m wondering, has anyone else found it necessary to trim the elements on these? My calculations are that about 1/8” off each end of the DEs would bring it up the 2 MHz needed. Opinions? -- ***Sent from Gmail on iPhone*** Mark D. Johns, Ph.D. K0JM Professor Emeritus of Communication Studies at Luther College, Decorah, Iowa USA Now residing in Minneapolis, Minn. ------------------------------------------------ "Get the facts first. You can distort them later." ---Mark Twain _______________________________________________ Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb