[SMCARA] Antenna Setup
Daniel Metcalf
kb3uun at gmail.com
Tue Nov 25 11:29:08 EST 2014
Found this http://www.fab-corp.com/pages.php?pageid=5.
Even at 1db loss that is a loss of 20.6% of your signal so on a 100 watt
signal one's ERP on a dipole would be something like 79.4 watts assuming
no loss anywhere else in the system and assuming my math is correct.
To tie this into my install questions LL400 at 200 feet on 40 meters has
a loss of 0.66 db so at the antenna with a solid piece of coax the ERP
would be approx 87.1 watts if I add a feed through connector total loss
would be (based on 1db plus coax loss) 1.66db or 30.8% at 100 watts
thats an ERP of approx. 69.2 watts assuming no other loss.
With all of that said is takes approx +-6db to move the S-Meter 1 S-Unit
so to go from S9 to an S8 one would would have to have enough loss in
the system to lower one's ERP to approx. 25 watts. But on the lower end
of the S-Meter during a noisy day this could be enough to keep you from
making contact.
Again this is assuming my math is correct.
Dan Metcalf -- KB3UUN
On Tue, 2014-11-25 at 10:56 -0500, Rene Ramirez wrote:
> http://www.eham.net/ehamforum/smf/index.php?topic=24185.0;wap2
>
>
> On Tue, Nov 25, 2014 at 10:55 AM, Rene Ramirez <w3bnyren at gmail.com>
> wrote:
> Without having a chart infront of me, the loss at HF
> frequencies shouldnt be much more than a 1db tops.
>
>
> On Tue, Nov 25, 2014 at 10:45 AM, Bill Jones
> <merc669 at gmail.com> wrote:
> I figured there would be some. How much, maybe not a
> lot. But that
> loss could be a contact(s). I was trying to save a
> buck or two and
> probably not worth it. And a 125 to 150 foot run
> should not be that
> expensive.
>
> Bill
>
> On Tue, Nov 25, 2014 at 10:39 AM, Daniel Metcalf
> <kb3uun at gmail.com> wrote:
> > 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
> >> >
> >> >
> >>
> ______________________________________________________________
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> >> > Message delivered to merc669 at gmail.com
> >>
> >>
> >>
> >> --
> >> KC3DEZ
> >> www.qrz.com
> >>
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> >
>
>
>
> --
> KC3DEZ
> www.qrz.com
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