[SMCARA] Antenna Setup
Bill Jones
merc669 at gmail.com
Tue Nov 25 10:45:56 EST 2014
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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>>
>>
>> --
>> KC3DEZ
>> www.qrz.com
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