Today's Message Index:
----------------------
1. 05:03 AM - Re: Questions about protecting the 4AWG wire in a remote battery installation. (Robert L. Nuckolls, III)
2. 08:40 AM - VHF Nav/GS Duplexer (Jared Yates)
3. 11:00 AM - Re: VHF Nav/GS Duplexer (DeWitt (Dee) Whittington)
4. 11:52 AM - Re: VHF Nav/GS Duplexer (The Kuffels)
5. 06:29 PM - Re: VHF Nav/GS Duplexer (Robert L. Nuckolls, III)
6. 06:55 PM - Re: VHF Nav/GS Duplexer (Jared Yates)
7. 08:40 PM - Re: VHF Nav/GS Duplexer (Robert L. Nuckolls, III)
8. 11:51 PM - Re: Questions about protecting the 4AWG wire in a remote battery installation. (Matthew Schumacher)
Message 1
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| Subject: | Re: Questions about protecting the 4AWG wire in a |
remote battery installation.
At 12:59 PM 8/4/2011, you wrote:
>
>List,
>
>I looked through the book and searched the archives, but can't find an
>answer to my question:
>
>I want to mount the battery under the seat and the contactors on the
>firewall. In order to do this I'll need to run 4awg wire about 6 feet.
> From the master contactor I'll run another 4awg wire to the starter
>contactor and I'll terminate my panel feed directly onto the master
>contactor.
>
>I don't see any circuit protection in any of the drawings, but it feels
>wrong to not have a wire that large running that distance unprotected.
You're right. That's why battery contactors are at the
battery . . . else they are not 'battery contactors'.
>Would be be ok to build a fusible link out of some 6awg wire that is
>only 3" long or would that cause to much voltage drop for the starter?
No . . . battery disconnect at the battery is a crash
safety idea . . . we don't run always-hot, high-current
feeders right of the battery in TC aircraft.
>Another option is to mount the contactors under the seat with the
>battery and run a 10awg wire up to the panel and install a fusible link
>on that wire.
Why not take the bus feeder off the starter contactor?
Bob . . .
Message 2
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| Subject: | VHF Nav/GS Duplexer |
I've been wondering lately about how I should provide glideslope input for my GNS430.
I saw several duplexing modules at the aeromart, but many of them had a
threaded connection instead of the usual BNC turn and lock. Are those threaded
connectors available, or should I look for a unit with BNC all around?
The other option that I've considered is making or buying a dedicated antenna,
though I'm not sure where I would put it. Would the elements need to be parallel
to the wingspan?
Message 3
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| Subject: | Re: VHF Nav/GS Duplexer |
Jared,
We had the same dilemma for our 430W. At Oshkosh I too looked at the
diplexers in the AeroMart. I was not impressed. What I saw were three bags
holding 5 units each for $19 per bag. All appeared to have been removed from
Cessnas or Pipers, etc. Yes, super cheap, but I had no real idea whether
they would work properly and many had screw fittings or a combination of
screw and BNC. We wanted all BNC.
So I just went ahead and bought a new Comant CI-507 from Aircraft Spruce
(11-17980) and got free freight and a discount. My situation is different
from most. I have three partners in building a Sportsman, so we split all
costs four ways.
Dee
On Fri, Aug 5, 2011 at 11:00 AM, Jared Yates <email@jaredyates.com> wrote:
> >
>
> I've been wondering lately about how I should provide glideslope input for
> my GNS430. I saw several duplexing modules at the aeromart, but many of them
> had a threaded connection instead of the usual BNC turn and lock. Are
> those threaded connectors available, or should I look for a unit with BNC
> all around?
>
> The other option that I've considered is making or buying a dedicated
> antenna, though I'm not sure where I would put it. Would the elements need
> to be parallel to the wingspan?
>
>
--
DeWitt Whittington
www.VirginiaFlyIn.org
Building Glasair Sportsman with 3 partners
Message 4
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| Subject: | Re: VHF Nav/GS Duplexer |
Jared,
<< I've been wondering lately about how I should provide glideslope input
for my GNS430. I saw several duplexing modules at the aeromart, but many of
them had a threaded connection instead of the usual BNC turn and lock. Are
those threaded connectors available, or should I look for a unit with BNC
all around? >>
The threaded connectors are available (see Mouser.com) but come in several
different types. You really need to know exactly what you need to get the
right one. Much better is to just get the BNC type. Chief seems to offer
the lowest price for the Comant CI-507 at about $130.
<< The other option that I've considered is making or buying a dedicated
antenna, though I'm not sure where I would put it. Would the elements need
to be parallel to the wingspan? >>
I put mine at the center top of my windshield, forward of a cross tube.
Don't even notice it is there when seated. While certainly optimum to have
the dipole parallel to the wing, it shouldn't be critical. Even end-on
(parallel to the fuselage) where dipoles have a null there should be enough
signal bouncing around to be functional. Try it and see.
Or better yet, for $6.00 in parts plus a small box and short piece of
coaxial cable make your own diplexer. See the attached diagram.
Tom Kuffel
Message 5
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| Subject: | Re: VHF Nav/GS Duplexer |
At 10:00 AM 8/5/2011, you wrote:
>
>I've been wondering lately about how I should provide glideslope
>input for my GNS430. I saw several duplexing modules at the
>aeromart, but many of them had a threaded connection instead of the
>usual BNC turn and lock. Are those threaded connectors available,
>or should I look for a unit with BNC all around?
The ones that are threaded but same size as BNC are
probably TNC connectors . . . there threaded cousin
to the bayonet lock BNC. The connectors are readily
available.
The diplexers are offered by several companies. Here's
one by RA Miller
Emacs!
and offered by Aircraft Spruce for under $100
http://www.aircraftspruce.com/catalog/avpages/av570coup.php
The DIY splitter suggested by Jim Wier was posted by
Tom. This can be even simpler to make than what Jim
suggested. I've uses a BNC "T" adapter
Emacs!
which feeds the VOR signal through the top
of the 'tee'. Then there's an RF game to be
played off the branch with the 10pF capacitor
and a couple of BNC chassis connectors
Emacs!
and some long 4-40 screws. You end up with
a more compact and robust version of Jim's
coupler with a minimum of disruption of the
VOR feedline characteristics.
I've got a program working out at Hawker-Beech.
I'll see if I can get a prototype over to the
RF lab and optimize the dimesions of the
10 pF capacitor wiring.
Jim called out exactly 1" overall lead length
for the capacitor. That's because the capacitor
COMBINED with the inductance of the leads forms
a series resonant turned circuit that picks off
the glide slope signal for routing it to the
GS receiver.
Once those dimensions are developed, I can
publish a good DIY project. Or you can build
what Jim has already suggested. It works too.
>The other option that I've considered is making or buying a
>dedicated antenna, though I'm not sure where I would put it. Would
>the elements need to be parallel to the wingspan?
Generally, yes. What kind of airplane are we
talking about?
GS signals on approach are VERY strong. The
antenna can suffer huge indignities of missed
optimization and still get you down the pipe
in good shape.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 6
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| Subject: | Re: VHF Nav/GS Duplexer |
Thanks everyone, I'm intrigued by the DIY duplex option, assuming that I can
find the parts. I especially like Bob's idea of a design that minimizes
losses to the VHF signal, since that was my only motivation for a separate
GS antenna. The airplane is a Bearhawk, which is a tailwheel tube and
fabric fuselage with a aluminum skin from the instrument panel to the nose
bowl.
On Fri, Aug 5, 2011 at 9:24 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 10:00 AM 8/5/2011, you wrote:
>
> >
>
> I've been wondering lately about how I should provide glideslope input for
> my GNS430. I saw several duplexing modules at the aeromart, but many of them
> had a threaded connection instead of the usual BNC turn and lock. Are
> those threaded connectors available, or should I look for a unit with BNC
> all around?
>
>
> The ones that are threaded but same size as BNC are
> probably TNC connectors . . . there threaded cousin
> to the bayonet lock BNC. The connectors are readily
> available.
>
> The diplexers are offered by several companies. Here's
> one by RA Miller
>
> [image: Emacs!]
>
> and offered by Aircraft Spruce for under $100
>
> http://www.aircraftspruce.com/catalog/avpages/av570coup.php
>
>
> The DIY splitter suggested by Jim Wier was posted by
> Tom. This can be even simpler to make than what Jim
> suggested. I've uses a BNC "T" adapter
> [image: Emacs!]
>
> which feeds the VOR signal through the top
> of the 'tee'. Then there's an RF game to be
> played off the branch with the 10pF capacitor
> and a couple of BNC chassis connectors
>
> [image: Emacs!]
>
> and some long 4-40 screws. You end up with
> a more compact and robust version of Jim's
> coupler with a minimum of disruption of the
> VOR feedline characteristics.
>
> I've got a program working out at Hawker-Beech.
> I'll see if I can get a prototype over to the
> RF lab and optimize the dimesions of the
> 10 pF capacitor wiring.
>
> Jim called out exactly 1" overall lead length
> for the capacitor. That's because the capacitor
> COMBINED with the inductance of the leads forms
> a series resonant turned circuit that picks off
> the glide slope signal for routing it to the
> GS receiver.
>
> Once those dimensions are developed, I can
> publish a good DIY project. Or you can build
> what Jim has already suggested. It works too.
>
>
> The other option that I've considered is making or buying a dedicated
> antenna, though I'm not sure where I would put it. Would the elements need
> to be parallel to the wingspan?
>
>
> Generally, yes. What kind of airplane are we
> talking about?
>
> GS signals on approach are VERY strong. The
> antenna can suffer huge indignities of missed
> optimization and still get you down the pipe
> in good shape.
>
> **
>
> ** Bob . . .
> ////
> (o o)
> ===========o00o=(_)=o00o========
> < Go ahead, make my day . . . >
> < show me where I'm wrong. >
> ================================
>
>
Message 7
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| Subject: | Re: VHF Nav/GS Duplexer |
At 08:50 PM 8/5/2011, you wrote:
>Thanks everyone, I'm intrigued by the DIY duplex option, assuming
>that I can find the parts. I especially like Bob's idea of a design
>that minimizes losses to the VHF signal, since that was my only
>motivation for a separate GS antenna. The airplane is a Bearhawk,
>which is a tailwheel tube and fabric fuselage with a aluminum skin
>from the instrument panel to the nose bowl.
Okay, Cessna put tens of thousands of GS antennas just
above the compass centered on the windshield. A simple
dipole 17" long fed in the center with 50 ohm coax
will perform quite well.
We had a fancy, clear plastic molded housing that
contained a copper foil strip. A short length of RG174
(itty-bitty 50 ohm coax) fed the center and took the
feed-line under the windshield and upholstery trim. I think
it spliced onto RG58 to take the signal on to the
GS receiver.
If you can manage RG400's larger diameter, it would
be the material of choice for getting the GS signal
down to your panel mounted receiver.
I proposed a methodology for fabricating a GS antenna
in the chapter on antennas . . . but forget the toroid
cores . . . they add no observable value.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 8
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| Subject: | Re: Questions about protecting the 4AWG wire in |
a remote battery installation.
On 08/05/2011 03:59 AM, Robert L. Nuckolls, III wrote:
>
>> Another option is to mount the contactors under the seat with the
>> battery and run a 10awg wire up to the panel and install a fusible link
>> on that wire.
>
> Why not take the bus feeder off the starter contactor?
>
>
> Bob . . .
Bob,
Seems like your solution is to put the battery contactor near the
battery, and the starter contactor on the firewall with the bus feeder
and alternator wired to that.
That is what I'll do, but doesn't that leave the 4awg wire between the
two contactors unprotected or will the battery contactor fail before the
wire does? Are you saying that this wire doesn't need to be protected
because it can be switched off by the pilot?
Thanks for the answers,
schu
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