KX-1/MP-1 SWR limits

[k6dgw]

Thanks for all the responses -- I have quite a few things to work on.
To summarize the thread:

1.  Use at least one ground radial.  I have been using the radials that
come with the MP-1, but I notice that things change a bit (like more rx
noise, or Z changes) when I grab the case of the KX-1 or 259.  I'm
planning on clamping the antenna to the rail of the "balcony" (aka
"shelf") on the ship hoping that will provide enough ground.  I'm taking
some wire with me as Plan "B".  

2.  I think I'm going to revisit my idea of marking the coil positions
and not taking some sort of SWR measuring device.  It's pretty obvious
now that marks made using 4 wire radials on a deck made of Trex are not
likely to be very good when the real ground is a 1,000 passenger, steel
boat in salt water!  The "Tenna Dipper" may be the ticket, and easier
than finding a big steel boat in N. Cal. to test with.

3.  Coax length to transform the impedance:  This was a good call from
W3FPR.  N6BV's TLW (on the CD in the 20th ed ARRL Antenna Book) will
help me investigate this from the warmth of the shack.  I may take a
couple or three different lengths of RG-58 if I can figure this out.

4.  And Wayne's reminder to me that the ATU tunes in steps rather than
continuous may be another key here.  A small change in the complex Z at
the antenna connector might move the match point in the ATU closer to
one of the attainable values.

Fortunately, I have some time before we steam off.  

Again, thanks for all the responses

Fred K6DGW
Auburn CA CM98lw

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[Ron D'Eau Claire-2]

Be very careful to wash the antenna, insulators and exposed coils and
connections with fresh water and dry them after each use. It only takes a
couple of hours to build up a layer of conductive salt crust on any exposed
surface, even when it's way above the water line. That "bracing" salt air
you smell everywhere is suspended droplets of salt water looking for things
to condense upon.

On old MF radio installations on large ships, the antenna feed-through
insulators above the radio room up at or above the navigating bridge level
(near the very top of the "house" on a ship) and were usually six inches or
so around and a foot or more long, with all the ripples to make the surface
distance from the hot lead to the ship as long as possible. Still, it was a
necessary duty for Sparky to constantly clean them or the salt accumulation
would short the RF right to ground.


Ron AC7AC



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