Today's Message Index:
----------------------
1. 05:17 AM - Re: Strobe discharge pop-pop-pop (Ralph E. Capen)
2. 06:19 AM - Re: Question about Annunciating Lights (Brett Ferrell)
3. 09:16 AM - Re: Cheaper 406mhz plb alternative? (David Chalmers)
4. 10:08 AM - Re: Odd ICOM IC-A200 Power/Ground Instructions ()
5. 12:18 PM - Re: Rotax 914 capacitor (Robert L. Nuckolls, III)
6. 01:02 PM - Re: Shielded Wire (Robert L. Nuckolls, III)
7. 02:56 PM - Re: Shielded Wire (Eric M. Jones)
8. 05:19 PM - Re: XM radio power cord (Robert L. Nuckolls, III)
9. 05:41 PM - Re: Strobe discharge pop-pop-pop (Robert L. Nuckolls, III)
10. 06:01 PM - Re: Question about Annunciating Lights (Robert L. Nuckolls, III)
11. 06:10 PM - Re: Cheaper 406mhz plb alternative? (Steve Thomas)
12. 06:12 PM - Re: Audio panel #inputs vs #sources (Robert L. Nuckolls, III)
13. 06:36 PM - Re: XM radio power cord (Dale Ensing)
14. 09:20 PM - Re: Question about Annunciating Lights (Fiveonepw@aol.com)
Message 1
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| Subject: | Re: Strobe discharge pop-pop-pop |
I'll be trying it outside soon and with the engine later - I'm almost thinking
the engine will drown it out...
-----Original Message-----
>From: Ken <klehman@albedo.net>
>Sent: Jan 9, 2008 11:45 PM
>To: aeroelectric-list@matronics.com
>Subject: Re: AeroElectric-List: Strobe discharge pop-pop-pop
>
>
>Ralph
>Have you tried it outside? My radio picks it up when in a metal hangar
>but not when outside. My intercom picks up a little as well via power
>supply or ground but hardly noticeable with the engine idling. So it
>might not be worth pursuing. The chapter on noise and grounding may be
>helpful. And if it is still noticeable a cheap automotive radio power
>filter on the strobe power supplies also helped in my case.
>Ken
>
>Ralph E. Capen wrote:
>>
>> I'm doing some system testing and I can hear a very slight pop each time my
strobes discharge through my headset. It doesn't break the squelch or prevent
me from hearing the radios - or stereo for that matter. No whining on the charge
cycles and I gotta listen carefully to catch the pop - but it's there.
>>
>> Is this strictly due to the high-voltage discharge in a 12V system? Is there
something I can due to get rid of this? Or should I take gladness that it's
faint, doesn't interfere, it's as good as it gets, have a coke and a smile and.......?
>>
>> Ralph
>
>
Message 2
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| Subject: | Question about Annunciating Lights |
I made my panel out of Honeywell microswitches. It's not really a cheap way,
but the results are nice, and it's fairly straight-forward, with "dead face"
(labels so you KNOW the lamp is out, because it cannot be read unless
illuminated from behind). I also built a push-to-test circuit.
http://www.velocityxl.com/Electrical.htm
(just the pictures)
http://www.velocityxl.com/annunciator.JPG
http://www.velocityxl.com/press_to_test.JPG
http://www.velocityxl.com/IMAGES2/GRT3.JPG
I bought mine from these folks http://www.fmw411.com/
Brett
Quoting Carl Morgan <zk-vii@rvproject.gen.nz>:
> I took Mark's work as a basis, and this is what I ended up with....
>
> Close up:
> http://www.rvproject.gen.nz/photos/2007-06/Web_Img_9760.jpg
>
> http://www.rvproject.gen.nz/dailylog/dailylog_2007-07-28.html the final
> look,
>
>
> http://www.rvproject.gen.nz/dailylog/dailylog_2007-06-18.html and
> http://www.rvproject.gen.nz/dailylog/dailylog_2007-06-19.html for some of
> the fabrication process.
>
> Just another possible source of ideas.
>
> Carl
>
> --
> Carl Morgan - ZK-VII - RV 7A - Inspection next Tue!
> http://www.rvproject.gen.nz/
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of
> Fiveonepw@aol.com
> Sent: 10 January 2008 18:14
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Question about Annunciating Lights
>
>
> Here's another take on rollin' yer own:
>
> http://websites.expercraft.com/n51pw/index.php?q=log_entry&log_id=5126
>
> Click on fotos for bigger view and Next Entry>> for more info (several
> pages) including wiring diagram, part #s etc...
>
> From The PossumWorks in TN
> Mark Phillips
>
>
> ----------------------------------------------------------------------------
> --
> Start the year off right. Easy ways to stay in shape in the new year.
>
>
> 10:16
>
Message 3
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| Subject: | Re: Cheaper 406mhz plb alternative? |
There's a good review here http://www.equipped.org/SPOT_ORSummer2007.htm
On 1/9/08, Charlie England <ceengland@bellsouth.net> wrote:
>
> ceengland@bellsouth.net>
>
> Anyone know any details about this product?
>
> http://www.findmespot.com/explorespot/spotmessenger.aspx
>
> IF it's using the public SARSAT satellites, maybe it would still work
> after the 1st mandatory subscription lapses. (Still be a lot cheaper
> than typical PLBs with built in GPS.)
>
> Charlie
>
>
Message 4
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| Subject: | Re: Odd ICOM IC-A200 Power/Ground Instructions |
Tim the 18 awg and 10 amp fuse is the broad brush
approach, one size fits all. Yes its overkill. You could
use a smaller awg wire and fuse. Also sometimes
people gang off of existing 10 amp CB's and therefore
18 awg is the correct wire size. I used 5 amp and
stayed with the 18 awg because I had it; A short run of
20 awg would work fine. They're just covered their bases.
Notice 13.8 volts spec? You can take some IR loss with
a 14.3-14.5 volt buss.
The wire diagram clearly shows ONE power and ONE
ground with a daisy chain or jumpers. Sorry have no
idea what he's talking about. TWIST? Really. May be
this is new and it does help but I am stumped. I went
with one wire for power and ground. George
If you find a 100% answer why, email me please, thanks
PS Its a great radio but instructions are lousy.
>From: Tim Lewis <Tim_Lewis@msm.umr.edu>
>Subject: AeroElectric-List: Odd ICOM IC-A200
>Power/Ground Instructions
>The ICOM IC-A200 (VHF Comm radio) installation
>instruction
(http://www.aeroelectric.com/Installation_Data/Icom_ICA200_Installation_Manual.pdf)
>depicts a 10 amp breaker, and tells the installer to "Use
>2 pairs of #18 AWG wires for power and power
>grounding wiring." This struck me as odd, since a
>single 18 AWG wire is normally used with a 10 amp
>breaker, and since the IC-A200 is rated to draw only
>2.6 amps (during transmit).
>I called ICOM tech support and spoke to Mike, who told
>me that I should indeed use two 18 AWG wires for
>power and two 18 AWG wires for ground, and that the
>two wires should be twisted together "to reduce
>interference". He further recommended twisting the end
>of the two wires together, aided by solder, and crimping
>this assembly into the supplied Molex terminal.
>I expressed some skepticism about the efficacy of
>twisting two 12V power wires together to reduce
>interference. I was unable to elicit an explanation of
>the mechanism by which the alleged interference
>reduction was to be achieved. I was also unable to
>elicit an explanation of why it should take two 18AWG
>wires in parallel to supply 2.6 Amps (peak) to
>a radio. I elected not to engage Mike in a discussion of
>the advisability of crimping a connector to a soldered wire.
>Does anybody have insight into reasoning or
>experience that lends credibility to the idea that two 18
>AWG wires should be used for power (and two for
>ground) in an ICOM IC-A200 radio installation?
>Thanks,
>Tim Lewis
---------------------------------
Never miss a thing. Make Yahoo your homepage.
Message 5
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| Subject: | Re: Rotax 914 capacitor |
At 12:13 PM 1/9/2008 -0800, you wrote:
>
>Hi All,
>B&C offer a couple different capacitors, 10,000uF @50VDC and 47,000uF
>@16VDC. Is one of these appropriate for use on the Rotax alternator?
>Thanks, Kevin
This is not a really critical capacitor with
respect to value but 16v is bit low for
a rating. 25V or more is the target. Furhter,
the "rule of thumb" for sizing is 1,000 uF per
amp of alternator output so the 10KuF/50v is
pretty good for the SD-8. Your system would
be better served by 20KuF/25V or larger.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 6
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| Subject: | Re: Shielded Wire |
At 06:12 AM 1/10/2008 -0800, you wrote:
>
>Bob:
>
>Maybe this is a little clearer:
>
>All the wires in the wing are shielded.
?Why?
>The wire used is MIL-DTL-27500TG2T14. That particular one is 12AWG, two
>conductor, twisted pair, shielded and sheathed. The unshielded version was
>not available without special order and long lead time. The weight
>difference between shielded and unshielded was 2.75lbs for 1,000 feet so I
>got the shielded version.
>
>There are no manufacturer's recommendations per se. Sizing for loads was
>done as per AC43-13-2A based on the power consumption rating for each load.
>
>All power loads have a power lead and a return lead. The sensors have how
>ever many wires are required by the sensor.
>
>Ignoring connectors, fuses, switches, ground buss etc, all power loads were
>to be routed as follows:
>
> Power lead: Bat(+) -to- Load.
> Return lead: Load -to- Bat (-) and, Load -to- Airframe (at Local
>Ground) -to- Bat (-)
> Shielding: - Bat(-) -to- Airframe (at Local Ground)
>
>I can't find where I read it but something led me to believe that if you
>were going to use shielded wire it was OK to do it the way I did.
I'm not sure I'm interpreting you words into an
accurate schematic of your architecture but since
the use of shielding where shielding adds no value,
then exactly how you wire it has no significance
with respect to performance.
>So, given that I am going to use the wire I have, that I am going to run a
>return lead for all power loads and that I want to hook up the shielding on
>the wire, what is the correct way to do it?
>
>Regarding the return lead, I'm pretty clear that the return lead should not
>be grounded at the Bat (-) and at a Local ground. Quote from your response:
>
>" One and only one ground . . . local is probably fine
> but not both places . . ."
>
>No problem changing it but why is it such a bad thing to do it that way.
>Using the landing light as an example. What harm does it cause to ground it
>locally and also run a lead back to the bat (-). Why is that worse than
>only grounding locally and the corollary, why is that not better than only
>running the lead back to the bat (-). Is the same applicable to the
>strobe's power unit and the fuel pump. Would it be the same for something
>like a flap actuator motor.
My personal goals for system design are to achieve
the desired level of performance with a minimum of
parts and minimized $time$ to acquire/install/maintain.
You appear to be asking advice for doing things that
I would not choose to do because they do not add
value under the design goals stated. Doing doesn't
necessarily degrade performance but it's certain
not to enhance it. Are there risks for venturing outside
the simple ideas that support conventional wisdom?
Difficult to predict but probably not.
>Regarding the shielding: I'm less clear on this. Removing the local ground
>from the return lead will also take the shielding out of the ground path
>from the Load to the Bat(-). But what about grounding the shielding itself.
>Again using the landing light as an example, what is the difference between
>grounding at both ends and grounding only at the Bat(-). Is the same
>applicable to the strobe's power unit, fuel pump and flap motor.
>
>Looking forward to your explanations.
A detailed trek through the physics from which
conventional wisdom and common practices evolved
is beyond the scope of what I can do here on
the List. I did a short-course on noise propagation
issues and solutions a few years ago at Hawker-
Beech . . . and that was a 4-hour, Power-Point
presentation.
Suffice it to say that if my mental image
for what you've described is correct,
then there is no reason to expect degradation
of performance and no reason to expect an
enhancement of performance. I.e, shielding
added without specific noise propagation
problems to be solved only adds to weight
of the airplane and cost of ownership. It
follows then that I have no advice based
on physics to offer for "doing it right".
Bob . . .
Message 7
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| Subject: | Re: Shielded Wire |
Okay, cut this message out and punch three holes into it and stick it into your
book. This is the cat's meow on coaxial cable shielding and grounding from Kimmel
Gerke Associates. I hope they balance my liberal use of their stuff with
the free advertising given here.
http://www.emiguru.com/kgb/sum1996.htm Kimmel Gerke Bullets.
"For many designers, cables and connectors are an afterthought. After all, they
just connect things together, right? But cables and connectors are major entry
and exit points for EMI into and out of electronic systems. They act as "hidden
antennas" for radiated energy, and "hidden conduits" for conducted energy.
"In fact, cables and connectors are so important, they are the often the first
things we check out when troubleshooting EMI problems in a system. Here are a
few thoughts on cable and connector design for EMI.
Trade off shielding for filtering. If you don't filter I/O interfaces, then you
must assume that the highest frequencies inside the unit will end up on the cable
wires. (Or you must assume the cables will intercept the highest frequencies
and bring them into the unit.)
"Just because that RS-232 interface is only operating in the kilobaud range doesn't
stop higher frequencies from hitching a "free ride" on the cables. We've
solved many radiated problems (emissions and immunity) by adding simple filters
to interfaces that were only supposed to carry "slow" or "low frequency" signals.
"The alternate to filtering the cables is shielding the cables. We generally prefer
to filter slower cables, since it's usually more cost effective and easier
to maintain EMI integrity.
"Ground the cable shield. If you do decide to use shielded cables, then the immediate
question becomes how best to ground the cable shield. The correct method
depends on both threat frequencies and circuit impedance levels.
"For problem frequencies below 10 kHz [audio], the preferred approach is to ground
one only one end of the shield. This is to prevent "ground loop" coupling
from the cable shield to the inner wires. This is particularly important for preventing
60 Hz coupling into low level/high impedance circuits used in audio
or instrumentation systems.
"Unfortunately, this is exactly the wrong thing to do for high frequency threats.
For most RF situations [above 10 kHz], the preferred approach is to ground
both ends of the cable shield, to minimize coupling at the open end due to standing
wave effects. So what do you do if both threats exist? You can ground one
end with a small capacitor (1,000- 10,000 pf typical) or you can use two shields
- one grounded on one end, and the other grounded on both ends. In the latter
case, the shields must be insulated from each other.
"One more case where both ends must be grounded is the low frequency/low impedance
case, where magnetic fields are the major culprit. In this case, the strategy
is to minimize "loop size" by providing an adjacent return path for noise
currents. This is often necessary in electrical sub-stations, where large 60 Hz
magnetic fields exist due to the high current levels. Most of the time, however,
single point grounding at low frequencies is the preferred approach.
"Use Care With Connector Terminations. This is extremely important for shielded
cables with EMI threats above about 1 MHz. Poor joints (or worse, "pigtail" connections
from the shield to the connector) are a leading cause EMI-induced failures
on shielded cables. We've seen 20 dB increases in emissions, and 10 fold
reductions in ESD immunity due to poor connections. (Remember, with a 1 nsec
edge rate, ESD is a 300 MHz EMI problem.)
"To maintain high frequency cable shield integrity, you need a circumferential
bond between the cable shield and the connector shell. In addition you need full
metal-to-metal between the mating connectors.
Finally, you need a solid connector-to-chassis connection. One problem we often
see here is with chassis connectors that overlap connector cutouts. The imprecise
fit creates a slot that very effectively couples high frequency energy directly
to/from the cable shield. Think in terms of a garden hose -you need a very
tight connection at the faucet, or else it leaks.
"What About The Cable Shield Itself? Yes, this is a valid concern, but only after
you have addressed the connector termination issues. For frequencies below
about 10 MHz, most cable shielding materials behave about the same, and provide
very respectable amounts of shielding. For frequencies above about 10 MHz, however,
the cable construction becomes important. Loose single braids become increasingly
leaky, so above 10 MHz, you may need high density braid shields. Double
braids work very well here, as do braid over Mylar cable shields. For high
frequencies, both shields should be connected together. "
--------
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=157322#157322
Message 8
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| Subject: | Re: XM radio power cord |
At 06:06 PM 1/9/2008 -0500, you wrote:
><densing@carolina.rr.com>
>
>A question regarding an XM Express radio that I use in the airplane and in
>the car.
>
>The power cord for the XM radio has a cigarette lighter type plug, is
>about three feet long with a mini coaxial plug on the radio end. Clamped
>on the cord are two cylinder shaped plastic devices (for lack of a better
>descriptive word). There is one on the cig. liter plug end and another
>smaller one on the radio end.
>The wire used in the power cord is very stiff and difficult to keep
>organized and out of the way. I would like to substitute another power
>cord that is coiled and stretchy. Much easier to manage and keep neat.
>What are the devices clamped on the cord and what is their function? What
>will be the impact if I used a power cord without the devices.
I suspect these are ferrite noise filters which
are commonly added to commercial products for the
for the purpose of reducing conducted electro-magnetic
interference between devices connected with the cable.
See:
http://www.aeroelectric.com/Pictures/Filters/Ferrite_EMI_Filter_2.jpg
http://www.aeroelectric.com/Pictures/Filters/Ferrite_EMI_Filter.jpg
If the devices you're seeing are similar in nature, then
it's probable that your device will FUNCTION if fitted
with a cord that does not have the filters.
But like any non-qualified device use in the airplane,
you should be cognizant of potential for interference
from the XM radio . . . whether filtered or not. Do some
tests and be ready to turn the radio OFF anytime another
radio system seems not to behave as expected.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 9
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| Subject: | Re: Strobe discharge pop-pop-pop |
At 01:36 PM 1/9/2008 -0500, you wrote:
><recapen@earthlink.net>
>
>I'm doing some system testing and I can hear a very slight pop each time
>my strobes discharge through my headset. It doesn't break the squelch or
>prevent me from hearing the radios - or stereo for that matter. No
>whining on the charge cycles and I gotta listen carefully to catch the pop
>- but it's there.
>
>Is this strictly due to the high-voltage discharge in a 12V system? Is
>there something I can due to get rid of this? Or should I take gladness
>that it's faint, doesn't interfere, it's as good as it gets, have a coke
>and a smile and.......?
When you think about the physics of what's going
on inside a xenon flash-tube, it has a great deal
in common with a lightning strike. As we all know,
a lighting strike can be "felt" both in terms of
magnetic and electrostatic effects, both of which
have the ability to radiate some distance and/or
couple to conductors.
What you're hearing is the broad spectrum, radiated
noise coming directly from the confines of the ionized
gasses in the tube when it fires.
When we put the first strobes on Cessna single-engine
airplanes in the 60's, there was a lot of fuss about
this mini-strike being heard in the ADF receivers.
We tried some glass with conductive coatings (reduced
light output) and fine-mesh screen wire (really hard to
work with).
Somebody finally noted that, "Bee, when you're tuned to
a station that was strong enough to be useable for either
listening or navigating, the "pop" was imperceptible
and effects on navigation nil."
Chances are that in flight, you're going to discover
the same thing. Now, if it does turn out to be a problem,
you'll need to repeat the same experiments we tried 40
years ago and perhaps some new ones. I'm aware of no
current tricks of the trade that would a apply.
Bob . . .
Message 10
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| Subject: | Re: Question about Annunciating Lights |
At 12:54 PM 1/9/2008 -0500, you wrote:
>Bob, it would help if you also added these pictures to the article...
>
>Bret Smith
>RV-9A "Fuselage"
>Blue Ridge, GA
Done. Thanks!
>> A fine piece of work! I've preserved this data in
>> an excerpt of the websit and posted it to:
>>
>>http://aeroelectric.com/articles/Roll_your_own_Annunicator_Panel.pdf
>
> Bob . . .
>
> ----------------------------------------)
> ( . . . a long habit of not thinking )
> ( a thing wrong, gives it a superficial )
> ( appearance of being right . . . )
> ( )
> ( -Thomas Paine 1776- )
> ----------------------------------------
>
Message 11
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| Subject: | Re: Cheaper 406mhz plb alternative? |
As far as 406MHz ELT goes, I currently have an ACK installed in my not-
yet-flying Glasair. This unit is not a 406 MHz unit. With the demise
of satellite tracking on 121.5, I wrote to ACK to ask if they had any
plans to release a 406 unit. The reply was that, yes, they have one
under development. It is an exact replacement for the 121.5 unit,
uses the same remote head, and uses easy to replace, commercially
available batteries (I don't remember what kind, but they were not
Alkaline). I don't remember the price exactly, but it was half of
what the lowest price alternative was. They said to keep watching
their web site and expected it to be available within the first half
of this year.
On Jan 10, 2008, at 9:01 AM, David Chalmers wrote:
> There's a good review here http://www.equipped.org/SPOT_ORSummer2007.htm
>
>
> On 1/9/08, Charlie England <ceengland@bellsouth.net> wrote:
> >
>
> Anyone know any details about this product?
>
> http://www.findmespot.com/explorespot/spotmessenger.aspx
>
> IF it's using the public SARSAT satellites, maybe it would still work
>
>
Message 12
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| Subject: | Re: Audio panel #inputs vs #sources |
At 11:16 AM 1/9/2008 -0500, you wrote:
><recapen@earthlink.net>
>
>Folks,
>
>I have three inputs that should be 'unswitched':
>AOA warning
>Traffic Alert
>AF3400EM Engine monitor
>
>My audio panel (PS Engineering PMA7000MS) has two unswitched inputs.
>Can I tie two of the sources to one input? I think there would only be an
>issue if they both went off at teh same time.
>Alternatively, I can put the third to a switched input and leave the
>switch on.
Put 100 ohm resistors in series with EACH of the three output
before bringing them together whether switched or not. See:
http://aeroelectric.com/articles/Rev11/18Audio_R11.pdf
Bob . . .
Message 13
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| Subject: | Re: XM radio power cord |
Thank you Bob. The 'devices' on the power cord look just like the ferrite
filters in the pictures. And thanks for the alert to possible interference
to other radio systems in the airplane.
Dale
> At 06:06 PM 1/9/2008 -0500, you wrote:
>
>><densing@carolina.rr.com>
>>
>>A question regarding an XM Express radio that I use in the airplane and in
>>the car.
>>
>>The power cord for the XM radio has a cigarette lighter type plug, is
>>about three feet long with a mini coaxial plug on the radio end. Clamped
>>on the cord are two cylinder shaped plastic devices (for lack of a better
>>descriptive word). There is one on the cig. liter plug end and another
>>smaller one on the radio end.
>>The wire used in the power cord is very stiff and difficult to keep
>>organized and out of the way. I would like to substitute another power
>>cord that is coiled and stretchy. Much easier to manage and keep neat.
>>What are the devices clamped on the cord and what is their function? What
>>will be the impact if I used a power cord without the devices.
>
> I suspect these are ferrite noise filters which
> are commonly added to commercial products for the
> for the purpose of reducing conducted electro-magnetic
> interference between devices connected with the cable.
>
> See:
>
> http://www.aeroelectric.com/Pictures/Filters/Ferrite_EMI_Filter_2.jpg
>
> http://www.aeroelectric.com/Pictures/Filters/Ferrite_EMI_Filter.jpg
>
> If the devices you're seeing are similar in nature, then
> it's probable that your device will FUNCTION if fitted
> with a cord that does not have the filters.
>
> But like any non-qualified device use in the airplane,
> you should be cognizant of potential for interference
> from the XM radio . . . whether filtered or not. Do some
> tests and be ready to turn the radio OFF anytime another
> radio system seems not to behave as expected.
>
> Bob . . .
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| Subject: | Re: Question about Annunciating Lights |
In a message dated 01/10/2008 8:21:26 AM Central Standard Time,
bferrell@123mail.net writes:
I made my panel out of Honeywell microswitches.
>>>
Slick! Where were these back when I needed 'em?! Nice work-
Mark
do not archive
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