[MRCA] M&S Net antennas

[Steve Gajkowski]

Start with a low dipole, easiest to make and then work from there.  Also,
not sacrificing any power in a tuner.

 

Not uncommon to get water penetration into coax, or wire for that matter.
Very common to have corroded wire inside the insulation on boats where the
wire is exposed to water.  

Coax seal  or duct seal is a good solution to the problem..  Tape or heat
shrink doesn't keep the water out.

 

  _____  

From: mrca-bounces at mailman.qth.net [mailto:mrca-bounces at mailman.qth.net] On
Behalf Of Alex J Rokowetz
Sent: Tuesday, January 29, 2013 10:31 AM
To: Ray Fantini
Cc: Military Radio Collector's Association
Subject: Re: [MRCA] M&S Net antennas

 

Ray,

As the other M&S net participants can tell you, I used the AT1011 vertical
with a tuner and a 100W output many many times and was heard by most
stations with a good signal.  When using a 20W radio and a tuned AT1011
vertical... different story.  Very hard to get into the net with that setup.
However when using a 20W radio and a resonant dipole (no tuner), everyone
usually copied me very well.  Also, a horizontal dipole antenna usually
provides me with a much lower noise level than a vertical.
 

Alex
K2AJR

  _____  

From: Ray Fantini <RAFANTINI at salisbury.edu>
To: "Military Radio Collectors Association (mrca at mailman.qth.net)"
<mrca at mailman.qth.net> 
Sent: Tuesday, January 29, 2013 10:22 AM
Subject: [MRCA] M&S Net antennas

 

Wanted to get something up and working for the M&S Net, got lots of radios
so that's not an issue but the problem appears to be antennas. Over the last
couple weeks I have discovered a couple things. First, of all the low
frequency antennas I have installed at the QTH the only good antenna I have
right now is a half wave inverted V cut for 160. My other two dipoles cut
for 40 and 20 meters both have coax full of water. Who would have thought
that if you have the ends open where they connect to the center sections
that water would get in and eventually come out the end of the cable in the
shack, I was surprised! Second, nothing I have appears to resonate at 5.3 Mc
and antenna tuners are harder to just throw together than first thought.
Third, I know nothing about antennas and propagation.  can tell you all
about VHF and microwave path analysis but this HF stuff is all voodoo, when
everyone starts all the arguments about NVIS and the like my eyes just glaze
over.  So with all this in mind this last weekend I strung up a vertical
wire insulated  one foot out from the top of the tower down to an insulated
support about thirty feet to a box with a taped coil and capacitor in it
tuned for minimum reflected power back at the radio. I think this would be a
vertical antenna, although do not know if it's affected by being that close
to the face of the tower. The problem is general consensus was that just
about everyone who was able to copy me says my signal sucks, so now it's
time for some improvements on my end. First question: is a vertical antenna
worth using? Can the poor performance be an issue on not having enough
radials? Would there be an advantage to shunt feeding the antenna to the top
of the tower? Or am I just wasting time working with a vertical in the first
place? And that leads to the second question: would it be better to just
throw together a dipole cut for that frequency and put that up? Or maybe the
same antenna as a sloper or inverted V?

 

RF


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