Today's Message Index:
----------------------
1. 07:33 AM - Re: antenna (Robert Sultzbach)
2. 07:33 AM - Re: antenna (Robert Sultzbach)
3. 07:36 AM - Re: firewall penetrations (Ken)
4. 09:11 AM - Re: firewall penetrations (Eric M. Jones)
5. 10:23 AM - Re: antenna (Robert L. Nuckolls, III)
6. 12:08 PM - Re: antenna (Brian Lloyd)
7. 01:18 PM - Re: Re:Garmin 296 power/battery (Dale Ensing)
8. 01:35 PM - Re: antenna (Robert G. Wright)
9. 01:37 PM - Re: antenna (simon miles)
10. 02:39 PM - Re: antenna (Brian Lloyd)
11. 03:28 PM - Re: antenna (Robert L. Nuckolls, III)
12. 03:53 PM - Re: antenna (Robert L. Nuckolls, III)
13. 09:30 PM - Re: Old Stuff (Mauri Morin)
Message 1
INDEX | Back to Main INDEX |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: Robert Sultzbach <endspeed@yahoo.com>
--- "Robert G. Wright" <armywrights@adelphia.net>
wrote:
> --> AeroElectric-List message posted by: "Robert G.
> Wright" <armywrights@adelphia.net>
>
> On Comant's spec sheets for DME/Transponder
> antennae, what is the
> significance of "Power RF?"
>
>
>
> Rob
>
>
>
>
>
>
> browse
> Subscriptions page,
> FAQ,
> http://www.matronics.com/Navigator?AeroElectric-List
>
>
> Admin.
>
>
>
>
>
>
>
>
>
>
>
Message 2
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: Robert Sultzbach <endspeed@yahoo.com>
--- "Robert G. Wright" <armywrights@adelphia.net>
wrote:
> --> AeroElectric-List message posted by: "Robert G.
> Wright" <armywrights@adelphia.net>
>
> On Comant's spec sheets for DME/Transponder
> antennae, what is the
> significance of "Power RF?"
>
>
>
> Rob
>
>
>
>
>
>
> browse
> Subscriptions page,
> FAQ,
> http://www.matronics.com/Navigator?AeroElectric-List
>
>
> Admin.
>
>
>
>
>
>
>
>
>
>
>
Message 3
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: firewall penetrations |
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
Hi Eric
Except for not having magnetos, I have that and more all going through a
single firewall opening. More than a hundred wires for dual efi and
ignition etc. I preferred two openings but space was tight and one
opening turned out to be easier for me. Most low voltage efi sensors are
shielded. Power and ground wires such as fuel injector wires or
contactor coil feeds are twisted/braided pairs where convenient in
accordance with good aeroelectric book wiring practice. All ground wires
(except the two firewall to engine ground straps) go through that
opening which I think is a good thing. FWIW just this week I
investigated the signals with a scope and could find no evidence of
crosstalk or problems due to routing everything through the same
opening. I had expected to find some magnetic coupling but did not. I
even temporarilly rerouted the normally noisy ignition coil feeds (high
current pulses with 100 volt or so spikes) but it made no difference to
anything that I scoped.
Separate subject but the 1994 subaru DIS ignition coils (4 cylinder) are
physically one unit with a minor effort to isolate the iron cores a bit.
I believe I did see evidence of secondary coupling evidenced by short
duration high voltage spikes in the high voltage circuit when the
alternate coil fires. Could of been just crosstalk in the spark plug
wires but I suspect magnetic coupling at the coils.
Ken
Erich_Weaver@URSCorp.com wrote:
>--> AeroElectric-List message posted by: Erich_Weaver@URSCorp.com
>
>
>Listers:
>
>Lots of wire hanging around my RV-7A right now, waiting to be tamed. Im
>following the Z-13/8 architecture and using a GRT EFIS/EIS. I labeled
>items on the Z-13 figure as being either aft or forward of the firewall,
>then sorted through the various EFIS/EIS wire call-outs to make a list of
>all the wires needing to go through the firewall so I could plan wire paths
>a little better:
>
>1 battery bus to battery contactor
>2 battery contactor to the S704-1 relay for the backup alternator
>3 battery contactor to main bus
>4 master switch to battery contactor
>5 push to start switch to starter contactor
>6 regulator for back-up alternator to backup alternator (two wires)
>7 regulator for main alternator to main alternator
>8 left ignition switch to p-mag (two wires)
>9 right ignition switch to p-mag (two wires)
>10 Groundpower switch to groundpower contactor
>11 EIS to CHT(8 wires)
>12 EIS to EGT wires (8 wires)
>13 EIS to Hall effect current sensor (two wires)
>14 Tach (EIS to P-mag)
>15 EIS to OAT sensor (not sure where to put OAT sensor yet)
>16 EIS to VDO oil pressure sensor
>18 EIS to oil temp sensor
>19 EIS to fuel pressure sensor (two wires)
>
>I would like to minimize the number of firewall penetrations. Are any of
>the above wires likely to cause problems with any others when bundeled
>together? Did I overlook any wires?
>
>For practical reasons only, Im considering two penetrations for the wires,
>one for the various contactor wires near the left side of the firewall, and
>the other for everything else, near the center or slightly to the left.
>
>Any thoughts from those that have been there before would be appreciated
>
>thanks guys
>
>Erich Weaver
>
>
>Erich Weaver
>URS Corporation
>130 Robin Hill Rd
>Santa Barbara CA 93117
>805-964-6010
>FAX 805-9640259
>
Message 4
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: firewall penetrations |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
Many times we copy successful methods long after new and better ways of doing things
are available. The idiom of firewall penetration devices using leather washers
and two crescent-shaped stainless parts came from the days of metal-cowled
airplanes and "A petrol-proof flexible tubing at last: an invention of the
greatest importance to aviation NACA TM-48 October 1921". The FAA firewall-penetration
flame test was designed for metal airplanes and engines where burning
was a common hazard.
My hunch is that too much attention is paid to this relatively minor task. What
might make more sense?--Armored fuel lines, fuel shutoffs, Purple-K; and a flame
detector under the cowl.
My Glastar instructions include a stainless steel firewall--but it looks like extreme
overkill to me. 3M Dot Paper will pass the FAA test and weighs a tiny fraction
of stainless steel sheet.
Consider fire safety as a complete system. Those towel bar holders and firestop
should not be depended upon as the whole solution.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=30164#30164
Message 5
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 04:08 PM 4/22/2006 -0500, you wrote:
>--> AeroElectric-List message posted by: "Robert G. Wright"
><armywrights@adelphia.net>
>
>On Comant's spec sheets for DME/Transponder antennae, what is the
>significance of "Power RF?"
>
>
>Rob
Hmmm . . . seems my reply was truncated. For antennas, there's
a design limit for the maximum power you can expect it to
handle. For example, a simple DME/Transponder antenna for
mounting to the bottom of an airplane could be severely
taxed at say 10,000 watts. It could be a current issue
where some part of the antenna might be overheating and
be damaged (not a problem with DME/Transponder antennas
because while PEAK power is perhaps 100-200 watts, the average
power is measured in milliwatts. If it's a voltage issue
(gaps in construction or capacitors arc over) then peak
power is a significant concern irrespective of
average power.
In any case, a DME/Transponder antenna you purchase for
use on an aircraft isn't going to be at-risk for damage
by any radio installed for that purpose at the power levels
commonly supplied. A 50-ohm antenna accepting 250 watts
of power sees peak currents on the order of 2.5 amps
and peak voltages on the order of 110 volts. Generally
not a big thing in the aviation antenna world.
The same company may well make antennas rated in the
killowatts where such things are a design challenge.
They may have a data sheet format that says
"tho shalt put a power rating on thy product"
so even the lowly DME/Transponder antenna gets a power
rating.
This gives rise to the neophyte's dilemma, "Gee, there's
a power rating stated for this product I might want to
buy for my airplane . . . how and why would I consider
this as significant for my buy-decision?" The answer
in this case is, "No big deal."
Bob . . .
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
Message 6
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
Robert G. Wright wrote:
> --> AeroElectric-List message posted by: "Robert G. Wright" <armywrights@adelphia.net>
>
> On Comant's spec sheets for DME/Transponder antennae, what is the
> significance of "Power RF?"
Transmitting antennas are usually rated for how much transmitter output
power they can handle. Remember that transponders and DMEs have
transmitters and transmit with peak power levels on the order of 200-300
watts. They transmit in short bursts so that the average power is low
but still, the peak voltages and currents are those of the 300W level.
This can cause arcing internally to the antenna if it isn't rated for
this power level.
But if the antenna says it is for a DME or transponder, you are pretty
safe using it for that function.
--
Brian Lloyd 361 Catterline Way
brian-yak at lloyd dot com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery
Message 7
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re:Garmin 296 power/battery |
--> AeroElectric-List message posted by: "Dale Ensing" <densing@carolina.rr.com>
Thanks Bob, you said
"We have three laptops in the family that use L-I batteries
for portable use and ALL are used as many hours or more with
external power plugged in. None of the instruction manuals
suggest that this is a 'bad' thing to do."
Bob,
The laptop experience is one of the reasons I asked the question. My wife
gave me her laptop when she needed to upgrade for her business. She had
always used the laptop with external power. When I tried to use the battery
I found it now has a very short endurance. Maybe 10 minutes. I know NiCads
develope a memory...do L-I also do that? Have tried cycling the L-I but no
luck.
Dale Ensing
do not archive
Message 8
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "Robert G. Wright" <armywrights@adelphia.net>
Bob, you're so quick on replies, you even beat me to labeling myself the
neophyte that I am! I'm just trying to wrap myself around all the info out
there on airframe and panel wiring that Revision 11 just can't hold. I'm
weighing the desire to do all my own wiring (time and learning) against
farming the panel out to $omeone el$e just to have it correct. Too bad
there're no avionics seminars around my area for the next foreseeable
future....
Rob
>
>On Comant's spec sheets for DME/Transponder antennae, what is the
>significance of "Power RF?"
>
>
>Rob
Hmmm . . . seems my reply was truncated. For antennas, there's
a design limit for the maximum power you can expect it to
handle. For example, a simple DME/Transponder antenna for
mounting to the bottom of an airplane could be severely
taxed at say 10,000 watts. It could be a current issue
where some part of the antenna might be overheating and
be damaged (not a problem with DME/Transponder antennas
because while PEAK power is perhaps 100-200 watts, the average
power is measured in milliwatts. If it's a voltage issue
(gaps in construction or capacitors arc over) then peak
power is a significant concern irrespective of
average power.
In any case, a DME/Transponder antenna you purchase for
use on an aircraft isn't going to be at-risk for damage
by any radio installed for that purpose at the power levels
commonly supplied. A 50-ohm antenna accepting 250 watts
of power sees peak currents on the order of 2.5 amps
and peak voltages on the order of 110 volts. Generally
not a big thing in the aviation antenna world.
The same company may well make antennas rated in the
killowatts where such things are a design challenge.
They may have a data sheet format that says
"tho shalt put a power rating on thy product"
so even the lowly DME/Transponder antenna gets a power
rating.
This gives rise to the neophyte's dilemma, "Gee, there's
a power rating stated for this product I might want to
buy for my airplane . . . how and why would I consider
this as significant for my buy-decision?" The answer
in this case is, "No big deal."
Bob . . .
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
Message 9
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: simon miles <simon.miles@skynet.be>
I'm intrigued. Why does a transponder or DME draw such high power? My
radio only draws about 5 watts and that seems to work perfectly well -
or is the peak draw actually much higher?
Simon Miles.
Brian Lloyd wrote:
> --> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
>
>
>
> Robert G. Wright wrote:
>> --> AeroElectric-List message posted by: "Robert G. Wright" <armywrights@adelphia.net>
>>
>> On Comant's spec sheets for DME/Transponder antennae, what is the
>> significance of "Power RF?"
>
> Transmitting antennas are usually rated for how much transmitter output
> power they can handle. Remember that transponders and DMEs have
> transmitters and transmit with peak power levels on the order of 200-300
> watts. They transmit in short bursts so that the average power is low
> but still, the peak voltages and currents are those of the 300W level.
> This can cause arcing internally to the antenna if it isn't rated for
> this power level.
>
> But if the antenna says it is for a DME or transponder, you are pretty
> safe using it for that function.
>
Message 10
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
simon miles wrote:
> --> AeroElectric-List message posted by: simon miles <simon.miles@skynet.be>
>
> I'm intrigued. Why does a transponder or DME draw such high power? My
> radio only draws about 5 watts and that seems to work perfectly well -
> or is the peak draw actually much higher?
It doesn't draw high power. It is just that it transmits very short
bursts of high power so while the peak power is high, the average power
(which is what your power bus has to deliver to the radio) is very low.
Think of it this way. It might transmit with 100W for 1/100th of a
second every second. The peak power is 100W but the average power is 1W.
The durations and rates are different than that in real life but it
gives you the idea how it works.
--
Brian Lloyd 361 Catterline Way
brian-yak at lloyd dot com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery
Message 11
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 03:33 PM 4/23/2006 -0500, you wrote:
>--> AeroElectric-List message posted by: "Robert G. Wright"
><armywrights@adelphia.net>
>
>Bob, you're so quick on replies, you even beat me to labeling myself the
>neophyte that I am! I'm just trying to wrap myself around all the info out
>there on airframe and panel wiring that Revision 11 just can't hold. I'm
>weighing the desire to do all my own wiring (time and learning) against
>farming the panel out to $omeone el$e just to have it correct. Too bad
>there're no avionics seminars around my area for the next foreseeable
>future....
We are ALL neophytes at many things. I presume your presence
here on the List is search out useful things to apply to your
decision making and/or to enhance your abilities to take on
new tasks. It's my pleasure and that of many others to share
what we've learned toward your goals.
Bob . . .
Message 12
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 08:08 PM 4/23/2006 -0700, you wrote:
>--> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
>
>
>simon miles wrote:
> > --> AeroElectric-List message posted by: simon miles
> <simon.miles@skynet.be>
> >
> > I'm intrigued. Why does a transponder or DME draw such high power? My
> > radio only draws about 5 watts and that seems to work perfectly well -
> > or is the peak draw actually much higher?
>
>It doesn't draw high power. It is just that it transmits very short
>bursts of high power so while the peak power is high, the average power
>(which is what your power bus has to deliver to the radio) is very low.
>
>Think of it this way. It might transmit with 100W for 1/100th of a
>second every second. The peak power is 100W but the average power is 1W.
>The durations and rates are different than that in real life but it
>gives you the idea how it works.
Brian nails it. Consider that power is a rate thing and does not
consider duration. For example, cruising down the road may require
40-50 horsepower from your engine . . . but how does that translate
to energy? To speak of energy, you must consider duration. Driving
500 miles might take ten hours . . . so while the power was 50 h.p.,
the energy was 500 horsepower-hours.
You can have a 100 watt lightbulb on the ceiling that you
turn on for one second out of each hour. Peak power is 100
watts, energy is 100/3600 watt-hours or 1/36th of a watt-hour.
Your transponder puts out a stream of 0.45 microsecond wide
pulses at 100W, or what ever the "power rating" of your transponder
is.
See http://www.airsport-corp.com/modec.htm
The strings happen over a span of 21 uS and repeats several times
each time the REPLY light on your transponder lights up. One might
say that the AVERAGE power for a reply of all "1" in the bit stream
approaches 50 watts . . . but this is still very periodic and even when
your're being painted by several radar sites, the average power over
say 10 seconds is less than 1 watt which accounts for about 100 millampers
of the input power to your transponder . . . the rest being lost
in running associated circuitry and losses in the transmitter's high
power output stage.
Tying this back to the antenna power rating question, knowing that
peak power is as much as 200W, the designer might have some voltage
issues to
consider but from an average power handling perspective, current
stresses to the antenna are trivial.
Bob . . .
Message 13
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
--> AeroElectric-List message posted by: "Mauri Morin" <maurv8@bresnan.net>
How 'bout the one for resistor color stripes?????
Bad Boys Rape Our Young Girls But Violet Gives Willingly
Black Brown Red Orange Yellow Green Blue Violet Gray White
0 1 2 3 4 5 6
7 8 9
Mauri Morin
Polson, MT
RV-8 N808M (reserved)
C180 N2125Z Flying
SEMPER FI
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|