Today's Message Index:
----------------------
1. 05:37 AM - Noise in Handheld Tx signal (Lapsley R. and Sandra E. Caldwell)
2. 07:07 AM - Re: Re: Z8 scrapped . . . ()
3. 07:13 AM - Re: Re: Z8 scrapped . . . (Robert L. Nuckolls, III)
4. 07:13 AM - Re: Noise in Handheld Tx signal (Robert L. Nuckolls, III)
5. 07:49 AM - Re: Solid State Contactors -- SuperSwitch? (James Robinson)
6. 09:28 AM - Re: Solid State Contactors -- SuperSwitch? (Robert L. Nuckolls, III)
7. 11:18 AM - Re: Z8 scrapped . . . (jonlaury)
8. 12:05 PM - Re: Re: Z8 scrapped . . . (Mark Richards)
9. 12:17 PM - Re: Z8 scrapped . . . (jonlaury)
10. 01:17 PM - Re: Re: Z8 scrapped . . . (Robert L. Nuckolls, III)
11. 01:29 PM - Re: Re: Z8 scrapped . . . (Robert L. Nuckolls, III)
12. 01:29 PM - Re: Re: Z8 scrapped . . . (Robert L. Nuckolls, III)
13. 04:03 PM - Re: Solid State Contactors -- SuperSwitch? (ROGER & JEAN CURTIS)
14. 05:48 PM - Re: Z8 scrapped . . . (jonlaury)
15. 07:02 PM - audio panel and com wiring (Dan Ballin)
Message 1
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| Subject: | Noise in Handheld Tx signal |
As is frequently the case, once you truly identify the root cause of a problem
the solution is obvious.
In this case we were using an external headset with the A24 hand held without an
external PTT. In other words we were using the hand held Tx button for the
PTT. The owners manual did not say if the external PTT was either recommend or
necessary with an external headset.
After discussing the problem with ICOM tech support they told me that when you
press the hand held TX button it connects the internal mic as well as the external
mic to the transmitted carrier. Consequently when we tried to transmit without
the engine running the Tx signal was reasonably quite but with the engine
running the mic in the hand held picked up the cockpit noise and transmitted
it along with the voice from the headset mic.
Correction of this problem was easy we just used an external PTT. Just one more
wire in the cockpit
I suspect that this may be common to other handhelds.
Roger
Time: 04:54:24 PM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Subject: Re: AeroElectric-List: Noise in Handheld Tx signal.
At 06:51 PM 2/28/2010, you wrote:
> >Caldwell" <lrsecaldwell@earthlink.net>
> >
> >We have a problem with excessive noise occurring in an ICOM A24.
> >Receive is good. The noise only occurs in the transmitted signal
> >while the engine is running, The noise is so bad the the voice is
> >not understandable. If the operator is about 100 ft from the A/B
> >with the engine running the noise is down to a level that is acceptable.
>
> >Th hsndheld is completely independent of the a/c. Internal
> >batteries and operation on the rubber duckie antenna. A headset is
> >used. Two different A24's with different headsets exhibit the same problem.
> >
> >There are no avionics in the plane except for the handheld. To
> >eliminate the possibility of interference from instruments or
> >alternator we tested with the master off and the problem still exists.
>
Then it's not electrical noise. Sounds more like acoustic
noise coming in through the microphone(s).
> >Previously the A24 was used acceptably with an open cockpit biplane,
> >a Murphy Renegade.
> >
> >One possibility could be excessive gain using the external mike, but
> >I am skeptical since it was acceptable in the biplane
> >
> >Any suggestions?
>
You need to identify the nature of the noise. Props sound
different that exhausts which sound different than
ignition, strobes, EL panel inverters, etc.
If you key the hand-held with the external headset
disconnected and a tape over the built in microphone,
is it quiet then?
Bob . . .
Message 2
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| Subject: | Re: Z8 scrapped . . . |
John,
I'm vaguely interested. What is it you are running that requires 30 amps
of power running as a backup? Is that air-conditioning? If you're
essential + engine bus pulls 30 amps, you've got big dependencies. This
is a backup up right, ala emergency power source?
Glenn E. Long
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
jonlaury
Sent: Sunday, March 07, 2010 10:27 PM
Subject: AeroElectric-List: Re: Z8 scrapped . . .
<jonlaury@impulse.net>
nuckolls.bob(at)aeroelect wrote:
>
> ... SNIP
> My recommendations for optimizing Noah's adaptation
> of an SD-20 into his project is replace the SB-1
> regulator with a generic "ford" style regulator,
> add a b-lead contactor to implement fat-wire
> disconnection when parked. Take field power/
> voltage sensing directly from the battery bus
> through a fusible link then to 5A breaker, crowbar
> ovm and then to contactor+regulator bus
> connection. Placard the system against
> simultaneous operation of both alternators.
>
> Bob . . .
Bob, previously I stated my desire to use a standby 30a ER alternator in
place of the SD 8 in Z-13/8. I've been lurking as others, like Noah,
pushed the thread.
I have a B&C LR-3 for the main alt and intended to use another one for
the standby. I have a mechanical "either, or" lockout device for the two
alternator field switches. As long as the two systems are mutually
exclusive, am I correct to understand that the prohibition re dual
LR-3's, mentioned at the beginning of your post, no longer applys? And
that the suggested mods in the quote above for Noah's system would not
apply to Z-13/8 as I intend to modify it?
Thanks,
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=289592#289592
Message 3
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| Subject: | Re: Z8 scrapped . . . |
>
>
>Bob, previously I stated my desire to use a standby 30a ER
>alternator in place of the SD 8 in Z-13/8. I've been lurking as
>others, like Noah, pushed the thread.
Understand.
>
>I have a B&C LR-3 for the main alt and intended to use another one
>for the standby. I have a mechanical "either, or" lockout device for
>the two alternator field switches. As long as the two systems are
>mutually exclusive, am I correct to understand that the prohibition
>re dual LR-3's, mentioned at the beginning of your post, no longer
>applys? And that the suggested mods in the quote above for Noah's
>system would not apply to Z-13/8 as I intend to modify it?
Generally. Here's some data points to ponder for
creative integration of two alternators onto a
single bus:
(1) You can have two alternators "always on" but
be aware that their ability to share total loads
is poor to nil . . . it takes special regulators
that talk to each other and direct the choir for
the proper mix of field excitation. Hence it is
recommended that two alternators be used in a main/sb
or main/aux mode where one is used to back up the
other.
(2) You can still operate in an always-on mode IF
you set the regulator setpoint for the aux alternator
about a volt lower than the main alternator. Like
the SB-1 controller functionality illustrated in
Z12. This provides an automatic transfer of load
to the aux alternator if the main shuts down.
CAUTION
This configuration offers a risk of NOT being
aware of a main alternator failure. The SB-1
regulator has circuitry that senses when the
aux alternator becomes loaded and lights a light.
That same light is use to annunciate alternator
overload . . . reduce loads until the light stops
flashing. If you don't have and SB-1, then some
simple circuit that watches alternator field
voltage and lights a light for anything over
1 volt of applied excitation is called for.
(3) You can operate in an either/or mode where
only one alternator is switched on at a time.
In this case, a low volts warning light prompts
the changeover.
CAUTION
I would advise against wiring the two systems
such than turning one alternator on disables the
other. There is no risk to hardware by having both
alternators on at a time . . . but crafting circuits
common to both systems adds a risk of single failure
disabling both alternators. Keep them separate.
-----*****-----
Beyond these three rules-of-thumb, I recommend striving
for max-cold of ship's wiring when all switches are
off. Try to limit protection for small always-hot
wires to 5A breakered, 7A fused. Strive for minimum
parts count. Strive for simple switching protocols
that limit if not eliminate any possibility that
mis-positioning of switches can go unnoticed and
negate your best laid plans and fondest wishes.
All of these ideas are NOT regulations. Just because
you do something that is not specifically illustrated
in the Z-figures is not necessarily courting unhappy
days in the cockpit. We build experimental airplanes
and exploration of alternative recipes for success
is encouraged . . . with limitations. Study, understand
and take action by DESIGN to eliminate single points
of system failure . . . which INCLUDES pilot understanding
of how the system will or will not function.
Bob . . .
Message 4
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| Subject: | Re: Noise in Handheld Tx signal |
At 07:21 AM 3/8/2010, Lapsley R. and Sandra E. Caldwell wrote:
>As is frequently the case, once you truly identify the root cause of
>a problem the solution is obvious.
>
>In this case we were using an external headset with the A24 hand
>held without an external PTT. In other words we were using the hand
>held Tx button for the PTT. The owners manual did not say if the
>external PTT was either recommend or necessary with an external headset.
>
>After discussing the problem with ICOM tech support they told me
>that when you press the hand held TX button it connects the internal
>mic as well as the external mic to the transmitted
>carrier. Consequently when we tried to transmit without the engine
>running the Tx signal was reasonably quite but with the engine
>running the mic in the hand held picked up the cockpit noise and
>transmitted it along with the voice from the headset mic.
>
>Correction of this problem was easy we just used an external
>PTT. Just one more wire in the cockpit
>
>I suspect that this may be common to other handhelds.
Great datapoint! Thanks for sharing.
Bob . . .
Message 5
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| Subject: | Re: Solid State Contactors -- SuperSwitch? |
good morning Bob
I was hoping you would offer some comment on these devises. Pros / cons / etc
Jim
James Robinson
Glasair lll N79R
Spanish Fork UT U77
________________________________
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Sun, March 7, 2010 6:02:40 PM
Subject: RE: AeroElectric-List: Solid State Contactors -- SuperSwitch?
>
>
>If you are
>planning on using one of these devices in your airplane, make sure you
>purchase the ones for a DC load. Some of the ones for AC load,
>require a zero crossing to switch and will not work for
>DC.
The device being discussed is offered by an aviation
equipment specialty house as a replacement for contactors
(where bi-directional current flow is needed) and another
version (relay) where uni-directional current flow will
suffice. They are expected to function in a DC power
system.
Bob . . .
Message 6
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| Subject: | Re: Solid State Contactors -- SuperSwitch? |
At 09:41 AM 3/8/2010, you wrote:
>good morning Bob
>I was hoping you would offer some comment on these devises. Pros / cons / etc
I've not seen detailed engineering data on any such
products to date. Certainly, the technology exists
to fabricate solid stage contactors. I think the
race car hobby/industry has been flirting with them
for some years.
My personal knowledge as to the performance of
products currently offered for sale is zero. I
would be interested seeing the detail data sheets
and/or doing lab tests on a device to look at
things like on-resistance, off leakage, transient
immunities, conducted noise, performance at temperature
extremes.
We KNOW that hard-metal contactors have VERY good
OFF and ON switching characteristics. Further, they're
simple, rugged and offer good value (service life and
performance vs. acquisition costs).
So the short answer is that pending further enlightenment
on my part, I'm not able to offer any insight.
Bob . . .
Message 7
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| Subject: | Re: Z8 scrapped . . . |
longg(at)pjm.com wrote:
> John,
>
> I'm vaguely interested. What is it you are running that requires 30 amps
> of power running as a backup?
>
> Glenn E. Long
>
> --
Hi Glenn,
I like to do arc welding while flying ;-).
I was initially considering Z-19 but was always a little uncomfortable with the
finite supply of power if alt 1 quit. So it wasn't so much that I needed 30 amps
(it's a 40a unit, but pulleyed to reduce wear, so 30 a @ max cruise rpm) as
what was available at a reasonable price and weight. Ignition, fuel pump, EFI
, navcom, EFIS put my electrical needs at about 12-15 amps. With just engine
needs at about 10-12 amps.
The extra alternator gives me more comfort and less weight for the same cost than
an extra battery.
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=289659#289659
Message 8
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| Subject: | Re: Z8 scrapped . . . |
Hi Bob:
Excellent description. I have a follow-up questions to #2:
(2) You can still operate in an always-on mode IF
you set the regulator setpoint for the aux alternator
about a volt lower than the main alternator. Like
the SB-1 controller functionality illustrated in
Z12. This provides an automatic transfer of load
to the aux alternator if the main shuts down.
CAUTION
This configuration offers a risk of NOT being
aware of a main alternator failure. The SB-1
regulator has circuitry that senses when the
aux alternator becomes loaded and lights a light.
That same light is use to annunciate alternator
overload . . . reduce loads until the light stops
flashing. If you don't have and SB-1, then some
simple circuit that watches alternator field
voltage and lights a light for anything over
1 volt of applied excitation is called for.
Wouldn't the aux come on whenever the system loads exceed the main
alternator's capability and the system voltage drops below the set point
of the aux regulator, not just when the main alternator fails? So set
up in that configuration, wouldn't the two LR-3's work just like the
LR-3/SB-1 combination except for the annunciation function? Then,
wouldn't you be able to tell which alternators are on and how hard each
is working by the load meters? In that situation, does it really matter
if they don't share the loads?
Thanks
Mark
Message 9
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| Subject: | Re: Z8 scrapped . . . |
nuckolls.bob(at)aeroelect wrote:
>
> >
> >
> >
> >
>
>
> Generally. Here's some data points to ponder for
> creative integration of two alternators onto a
> single bus:
> ....SNIP....
>
> Bob . . .
Give a man a fish and he eats for a day.
Teach a man to fish and he eats for a lifetime.
I am now a fisherman.
Thanks Bob.
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=289670#289670
Message 10
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| Subject: | Re: Z8 scrapped . . . |
>
>
>Wouldn't the aux come on whenever the system loads exceed the main
>alternator's capability and the system voltage drops below the set
>point of the aux regulator, not just when the main alternator fails?
>So set up in that configuration, wouldn't the two LR-3's work
>just like the LR-3/SB-1 combination except for the annunciation
>function? Then, wouldn't you be able to tell which alternators are
>on and how hard each is working by the load meters? In that
>situation, does it really matter if they don't share the loads?
>
Very perceptive. You're correct. The caveat is to make SURE
the alternator with the higher setpoint is adequately cooled.
There have been any number of advisors calling for de-rating
an alternator's load or adjusting pulleys to slow it down . . .
with some notion of increasing service life for forestalling
early failure due to "working too hard".
Every alternator is capable of running for rated service
life (usually thousands of hours) at FULL rated output.
If the OBAM aircraft community is guilty of an important
function of well considered design is that we generally
haven't got a clue as to how well we cool . . . or don't
cool some temperature sensitive components.
There are thousands of 60A or larger alternators flying
very successfully on OBAM aircraft with very low failure
rates due to overheating. But this probably has more to
do with accidental de-rating. Few airplanes need more than
20A of snort for 90 plus percent of their missions.
Many of those builders thinks he can install some power
hungry electro-whizzy because he believes he's got lots
of headroom in the as-installed alternator.
When we certify a new alternator, rules of the game
call for an extended climb at Vy with the alternator loaded
to full rated output. We plot the temperature rise curve
in order to extrapolate the asymptote (temperature rise
ceiling). We then correct for hot day conditions. Anticipated
worst case for temperatures on diode heatsinks and stator
windings cannot exceed manufacturer's ratings.
So before you launch off to deliberately allow one
alternator to operate continuously in a current limited
condition (usually a few percent higher than nameplate
rating), be prepared to determine that the alternator
is not running with one foot in a bucket and the other
in a fire.
Back in the heyday of light twins with generators,
turning on all electro-whizzies demanded that BOTH
power sources carried their "share" of the load.
This is really easy to do with carbon pile regulators.
A simple equalizer winding added to the regulator's
magnetics would allow the two regulators to compare
notes and shift loads between generators for balancing.
http://aeroelectric.com/Pictures/Schematics/Parallel_Aircraft_Generators.jpg
Sharing was important then because service life (brush
wear) was affected by system loads. Alternators do
not suffer such problems . . . but they're more difficult
to parallel too.
Designing a system that expects one of two alternators
to operate in a current limited mode is not an automatic
recipe for failure . . . but you need to do your
homework.
Bob . . .
Message 11
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| Subject: | Re: Z8 scrapped . . . |
>
>
>I was initially considering Z-19 but was always a little
>uncomfortable with the finite supply of power if alt 1 quit. So it
>wasn't so much that I needed 30 amps (it's a 40a unit, but pulleyed
>to reduce wear, so 30 a @ max cruise rpm) as what was available at a
>reasonable price and weight.
Service life is not enhanced by slowing it down.
Performance in the original automotive application
counted on thousands of hours under condtions far
worse than on your airplane. If you'd really like
to get 40A from it, change the pulley ratio. It
will run cooler by turning faster for the same
load.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 12
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| Subject: | Re: Z8 scrapped . . . |
>
>Give a man a fish and he eats for a day.
>Teach a man to fish and he eats for a lifetime.
>
>I am now a fisherman.
>
>Thanks Bob.
Thank YOU for helping spread the value of
what this List has to share.
Bob . . .
Message 13
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| Subject: | Solid State Contactors -- SuperSwitch? |
If you are
planning on using one of these devices in your airplane,
make sure you
purchase the ones for a DC load. Some of the ones for AC
load,
require a zero crossing to switch and will not work for
DC.
The device being discussed is offered by an aviation
equipment specialty house as a replacement for contactors
(where bi-directional current flow is needed) and another
version (relay) where uni-directional current flow will
suffice. They are expected to function in a DC power
system.
Bob . . .
One of the devices referenced previously on
this website http://www.futurlec.com/RelSS.shtml pictured an AC device
JGX-1505FB. I seem to recall way back in a previous life that some of
these
similar devices required that the output go to zero before it would shut
off. I may be wrong, since it has been many moons since I have worked
with
this device. This is why I mentioned above to be careful when selecting
your solid state relay.
Roger
Message 14
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| Subject: | Re: Z8 scrapped . . . |
nuckolls.bob(at)aeroelect wrote:
>
> >
> >
> > (it's a 40a unit, but pulleyed
> > to reduce wear, so 30 a @ max cruise rpm)
> >
> >
>
> Service life is not enhanced by slowing it down.
> Performance in the original automotive application
> counted on thousands of hours under condtions far
> worse than on your airplane. If you'd really like
> to get 40A from it, change the pulley ratio. It
> will run cooler by turning faster for the same
> load.
>
>
> Bob . . .
>
> ---------------------------------------
AHA! Point taken.
J
DO NOT ARCHIVE
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=289713#289713
Message 15
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| Subject: | audio panel and com wiring |
This may be obvious to most, but I found a flaw in my wiring schema
that I figured I'd share. This is somewhat specific, but I am sure
many are in a similar situation. I have a Lancair Legacy with a PMA
7000 audio panel and SL30 as com 1 and an SL40 as com 2. I wired the
panel using Z-14 (2 separate battery/alternator busses). The issue is
that I wired com 1 and the audio panel on the same buss, so if I loose
power on that buss, I have lost the ability to use a com. Since the
default for the PMA when it is off is com1, com 2 is not available.
The solution is to make sure com 1 and the audio panel are on
different busses. Of course all I have to do is hit the crossfeed and
things are good again, but in a busy stressful situation I'd rather
have the default a working com.
Dan Ballin
LEG2 #286
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