[SMCARA] Antenna Setup
Daniel Metcalf
kb3uun at gmail.com
Tue Nov 25 10:39:03 EST 2014
Bill,
When I was a teenager I had a job that enabled me to work on the S-3B
Viking II (one of the aircraft I worked on is in the museum parking lot
it has 770 on the side of it). I worked on two projects for that
aircraft namely the AG-65M Maverick Missile Installs where I was in
charge of the wiring harnesses from the fuselage to the weapons pylon
and the second project was a test kit to verify wiring of the aircraft's
radar altimeter. Several S-3s were lost during night-time carrier
operations due to the fact the radar altimeter was indicating that is
was safe to retract the landing gear and flaps and when the pilots did
they stalled and dropped the plane into the ocean. Several crews were
lost. We went to Jacksonville, FL to examine the aircraft from the
Checkmates squadron before their deployment and I am glad we did. With
what we discovered it was amazing the systems worked at all. Anyway I
digress.
It was working to verify the wiring of the radar altimeter systems that
I became very familiar with using a TDR. This device sent a signal
through the wiring and was able to graphically show us where each of the
bulkhead connectors were and any defects that may have been in the
wiring. While examining a aircraft one day, I was told by an engineer
that at each of those bulkhead connectors we were losing approx. 3db of
signal. Which to put in simple terms, through each bulkhead connector we
were losing approx. half of the signal. Now I understand the frequencies
we use are much much lower than that used by the Radar Altimeter system
and at those higher frequencies it does not take much to cause loss. But
if I am not mistaken there is still some truth in the logic that there
is loss of signal each time we go through a in-line barrel connector. It
may not be 3db like it was in the aircraft but there is some.
Dan
On Tue, 2014-11-25 at 10:03 -0500, Rene Ramirez wrote:
> Honestly. Ive never EVER liked that crap. Its just tar/mastic and if
> you ever have to get into that barrel connector, you are better off
> just cutting it. Either that or a whole bunch of mineral spirits to
> help loosen it. Seriously..cut it.
>
>
> That being said. If you must use a barrel connector use Scotch-3m
> linerless rubber tape and 88+ (its thicker) followed by a liberal
> amount of scotch-kote. That combination is good to like...88Kv,
> buryable and comes off with a little pursuasion from a razor knife.
>
>
> On Tue, Nov 25, 2014 at 9:44 AM, Bill Jones <merc669 at gmail.com> wrote:
> I was going to ask your #2 also since I have the end-fed to a
> post and
> thought of just extending it by 100feet what the downside
> would be if
> I barreled connected it and then sealed it with coax seal
> rather than
> pull a new cable from the shack to the new antenna I was
> thinking of
> to replace the end-fed next year.
>
> Bill
>
> On Tue, Nov 25, 2014 at 8:37 AM, Daniel Metcalf
> <kb3uun at gmail.com> wrote:
> > Good Morning All,
> >
> > Just wanted to get some thoughts on a personal antenna
> installation that
> > I have been considering. Please let me know what you think.
> >
> > Earlier this year I purchased a 160 sloper from Jim (KJ4WAS)
> but have
> > not installed it yet for a couple reasons. First, I needed
> to get
> > everything together to do the install and Secondly, I needed
> to wait for
> > the leaves clear off of the tree that seems to be the best
> candidate for
> > the installation. Lastly, having two back surgeries in a
> single year
> > have limited my ability to get it done.
> >
> > A couple things have been ringing in my head as possible
> issues so when
> > my launcher failed (line broke and I lost the weight on
> launch) last
> > night I was not too heart broken.
> >
> > Possible Issues:
> >
> > 1) Between my house and the tree in which I would like to do
> the install
> > is my vertical antenna and radial field. I have been
> considering the
> > effects that could be caused by running the new feed-line
> either over or
> > under the existing radial field.
> >
> > 2) The tree in which I would like to do the install is ~60ft
> tall and
> > greater than 100ft from the house so I am seeing that I am
> going to need
> > ~200ft of coax (which I already have) the thing that I have
> been
> > considering is if I should leave the feed-line as one piece
> or put in an
> > in-line adapter at the base of the tree.
> >
> > My current thinking is that Issue #1 is going to be the
> bigger issue. So
> > much so that I might need to consider a different tree or
> would be
> > inclined to move the vertical antenna to another part of the
> back yard.
> > Which for anyone who has installed a vertical would know how
> much of a
> > pain that would be especially with buried radials, coax and
> an 8ft
> > galvanized pipe driven in the ground as the base.
> >
> > For Issue #2 I am thinking of just leaving the coax as a
> single piece to
> > avoid any possibility of water getting into the connectors.
> The losses
> > for the coax at 200ft is only ~0.66 db on 40m to ~1.76db at
> 6m based on
> > JefaTech's Website and based on needing the full 200ft of
> LL400 so the
> > distance is not that big of an issue.
> >
> > Any thoughts?
> >
> >
> > Thanks,
> > Dan Metcalf -- KB3UUN
> >
> >
> ______________________________________________________________
> > SMCARA mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/smcara
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:SMCARA at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list:
> http://www.qsl.net/donate.html
>
> > Message delivered to merc669 at gmail.com
>
>
>
> --
> KC3DEZ
> www.qrz.com
> ______________________________________________________________
> SMCARA mailing list
> Home: http://mailman.qth.net/mailman/listinfo/smcara
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:SMCARA at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list:
> http://www.qsl.net/donate.html
> Message delivered to w3bnyren at gmail.com
>
>
>
More information about the SMCARA
mailing list