[MRCA] Commo #4 MX-6707

[Tim]

Hi Mark - Nice installation!  I was unaware of the "shoebox" variant for
these antenna matching units.  Just the MX-6707/VRC types usually seen.
Here is what I have learned about the AS-1729/VRC system and how I have
used it if you're bored:
https://www.n6cc.com/as-1729-vrc-vhf-whip-antenna/
Thanks for the link to the Army's failure modes study. Significant issues
with water intrusion, big project to address it.  Lots of them fielded!
Tim
N6CC

On Wed, Jun 5, 2024 at 3:53 PM MilComm Guy <m38inmaine at gmail.com> wrote:

> I received a comment about the high failure rate of the round tuning units
> and he is correct, the military did a study on how to try and correct this.
>
> https://apps.dtic.mil/sti/tr/pdf/ADA118281.pdf
>
> Leaving the antenna tied down opens the spring coils and allows water in,
> also the plastic version develops cracks where water can get in.  When
> looking to buy one check for cracks and make sure the manual tuning knob on
> the bottom turns freely, if not pass on it.
>
> The MX-2799 tuning unit has the spring base mounted separate from the
> tuning unit allowing more flexibility of where you can mount the tuner and
> still have the antenna vertical and no chance of water entry from a tied
> down antenna.
> [image: DSCN0447.JPG]
> [image: DSCN0445.JPG]
>
> Mark
> K1HF
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