Today's Message Index:
----------------------
1. 12:16 AM - Re: AeroElectric-List Digest: 8 Msgs - 06/18/12 (Franz Fux)
2. 03:55 AM - Re: Generator suppressor (Robert L. Nuckolls, III)
3. 04:01 AM - Re: SL-40 (Robert L. Nuckolls, III)
4. 04:21 AM - Re: Generator suppressor (Jay Hyde)
5. 07:39 AM - Re: Generator suppressor (Robert L. Nuckolls, III)
6. 07:43 AM - Re: Viking Schematic (Robert L. Nuckolls, III)
7. 07:55 AM - Re: Hall Effect rpm sensor (Robert L. Nuckolls, III)
8. 08:33 AM - Re: Hall Effect rpm sensor (Mike Welch)
9. 09:26 AM - Re: Generator suppressor (Jay Hyde)
10. 10:24 AM - Re: Viking Schematic (user9253)
11. 12:52 PM - Re: OBS resolver signals (David Josephson)
12. 01:12 PM - Antenna length (Rob Henderson)
13. 02:21 PM - Re: Antenna length (Peter Pengilly)
14. 04:55 PM - Re: Antenna length (John MacCallum)
15. 07:17 PM - Re: Antenna length (DeWitt (Dee) Whittington)
Message 1
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Subject: | Re: AeroElectric-List Digest: 8 Msgs - 06/18/12 |
only intermittent access to e-mail until June 19th, in an urgent matter contact
info@lastfrontierheli.com
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Subject: | Re: Generator suppressor |
>, but I am not sure of what values of inductance and capacitance to
>use- does anyone have these values squirreled away somewhere so that
>I can make a new suppressor?
Not sure what these would be. I'd leave them
off until you find that they are necessary.
Most generator noises were antagonistic to
ADF and low frequency nav services. You probably
don't need them now.
Bob . . .
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At 08:22 AM 6/18/2012, you wrote:
Bob,
A good thought, but the first fuse blew as I was doing that very
thing (running with the alternate feed switch closed). So for the
last 12 hours or so, I have run with the alternate switch off. Just
strange that it took 12 hours to pop again. Like one of the guys
suggested, when I do my tests I might find the radio draw is dancing
around the 5A limit...so over time it would probably eat away at the
fuse until it fails. I guess the easy fix could be to throw the 7.5 A
in there, but it still bothers me that the radio specs indicate the
high end draw at tx should be 3.5A (going from memory here) or close
to that. I am off to the field now and hope to gather some useable
information today. Just hope I don't blow a fuse out there...should
get up to about 110 in Phoenix today.
As I mentioned before, fuses should be 'de-rated'
about 25%, 50% doesn't hurt a thing. If your radio
is drawing that much current, there has to be a reason.
What are your bus voltage measurements showing?
Bob . . .
Message 4
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Subject: | Generator suppressor |
Thanks Bob,
I was thinking along the same lines. It seems to me that these are simply a
broad spectrum smoothing filter. I think that I will test run the generator
on my lathe and have a look at the output on a scope to see if it looks too
rough- a mass produced line filter may just do the job if any smoothing is
required.
Jay
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: 19 June 2012 12:54 PM
Subject: Re: AeroElectric-List: Generator suppressor
--> <nuckolls.bob@aeroelectric.com>
>, but I am not sure of what values of inductance and capacitance to
>use- does anyone have these values squirreled away somewhere so that I
>can make a new suppressor?
Not sure what these would be. I'd leave them
off until you find that they are necessary.
Most generator noises were antagonistic to
ADF and low frequency nav services. You probably
don't need them now.
Bob . . .
Message 5
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Subject: | Generator suppressor |
At 06:20 AM 6/19/2012, you wrote:
>
>Thanks Bob,
>
>I was thinking along the same lines. It seems to me that these are simply a
>broad spectrum smoothing filter. I think that I will test run the generator
>on my lathe and have a look at the output on a scope to see if it looks too
>rough- a mass produced line filter may just do the job if any smoothing is
>required.
>
>Jay
That's probably more trouble than it's worth.
Generators produce a lot of trash. A 'scope
picture is almost never informative. A spectrum
analyzer would give you a notion of potential
EMC problems but know that DO-160 calls for
'qualified' devices to shrug off up to 1.5 volts
pk-pk over 1 to 5 kHz
http://tinyurl.com/78kwfk8
and lesser amounts above and below. A 'scope
picture of this is pretty spectacular. Alternators
are less 'spikey' but still offer considerable
ripple voltage.
Any filters you might need would go to issues
in the RF spectrum
http://tinyurl.com/7wrhxbg
and cannot be observed in a time domain display.
Bob . . .
Message 6
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Subject: | Re: Viking Schematic |
At 04:34 PM 6/17/2012, you wrote:
I am helping a friend with a schematic for his Viking powered
airplane. See the attached pdf. Is it safe to eliminate the
Schottky diode in the lower left corner? I want to remove the diode
because it is one more failure point and I do not know if it can
handle the full load of the main bus, perhaps as much as 25 or 30
amps. The concern is a short in the alternator or starter circuit
(Or is this a remote possibility?) with no way to isolate it without
stopping the electrically dependent engine.
Thanks for any advice.
Joe
--------
Joe Gores
The rationale for this design is not clear just
from the schematic. It appears to borrow nothing
from the design philosophies for failure tolerance
offered in the Z-figures. I'd have to know more about
why it was all wired this way. What are the
current demands for the two ignition systems?
Bob . . .
Message 7
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Subject: | Re: Hall Effect rpm sensor |
At 05:21 PM 6/18/2012, you wrote:
>List guys,
>
> Can someone direct me to "complete rpm sensor circuit", including
> either a digital or analog gauge
>that would go along with it?
>
> I have need of something that will display visually a rotating
> motor's shaft. A Hall Effect circuit
>would be fine, but I'm open to anyone's suggestion if they have a
>better idea how to monitor rpms
>of a motor. FYI, the motors will turn at a relatively slow 200-250
>rpm (if that matters).
>
> If you know of a specific gauge, or LCD display, that could read
> these rpms, I'd appreciate that, too.
>
>Thanks in advance,
>Mike Welch
What is the rpm range of interest? Is the
instrument to be permanently mounted or is
it a 'test' or 'setup' environment that could
use a hand-held? See:
http://tinyurl.com/77ulekb
http://tinyurl.com/77lw4bs
If you need a permanent, panel mounted
instrument, you could use something like
this
http://tinyurl.com/7nxrh4w
but you'd need to build a sensor and
some interface electronics. As long as
you're building stuff, the data can be
displayed on a small, analog instrument
where a customized scale sized to your
task is pretty easy.
https://matronics.com/aeroelectric/Catalog/Loadmeter.jpg
Bob . . .
Message 8
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Subject: | Hall Effect rpm sensor |
Bob=2C
Thank you for replying!
Here are some of the parameters:
1) motor shafts are anticipated to rotate between 0-300 rpm2) the tach-di
splays need to be remotely=2C and permanently mounted (in a console)(I real
ly like that digital tach you suggested!!)3) the 'precise' motor rpms do n
ot have to be "highly accurate"=2C but they do need to be consistant.(in ot
her words=2C if the shaft is actually spinning at 307 rpms=2C and the gauge
says "320"=2C that's fine=2C as long as each time it is consistantly off t
he same amount!)
I did find a very nice electronics package that was close to what I'm loo
king for=2C but it had a couple of glitches. First glitch was the rpm rang
e it measured=2C which was way too high=2C and the second glitch was the tw
o 7 segment displays=2C when I would prefer an actual tachometer like the o
ne you suggested. See:http://www.eio.com/p-23310-velleman-k2625-digital-ta
chometer.aspx
Thanks for your help=2C Bob=2CMike
Message 9
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Subject: | Generator suppressor |
Sigh... its never simple :-)
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: 19 June 2012 04:38 PM
Subject: RE: AeroElectric-List: Generator suppressor
--> <nuckolls.bob@aeroelectric.com>
At 06:20 AM 6/19/2012, you wrote:
>--> <jay@horriblehyde.com>
>
>Thanks Bob,
>
>I was thinking along the same lines. It seems to me that these are
>simply a broad spectrum smoothing filter. I think that I will test run
>the generator on my lathe and have a look at the output on a scope to
>see if it looks too
>rough- a mass produced line filter may just do the job if any smoothing
>is required.
>
>Jay
That's probably more trouble than it's worth.
Generators produce a lot of trash. A 'scope
picture is almost never informative. A spectrum
analyzer would give you a notion of potential
EMC problems but know that DO-160 calls for
'qualified' devices to shrug off up to 1.5 volts
pk-pk over 1 to 5 kHz
http://tinyurl.com/78kwfk8
and lesser amounts above and below. A 'scope
picture of this is pretty spectacular. Alternators
are less 'spikey' but still offer considerable
ripple voltage.
Any filters you might need would go to issues
in the RF spectrum
http://tinyurl.com/7wrhxbg
and cannot be observed in a time domain display.
Bob . . .
Message 10
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Subject: | Re: Viking Schematic |
Bob,
My friend is building an RV-12 with an automotive engine, the Viking, which is
fuel injected and electrically dependent. The power requirements for the ECU
are not known but Viking uses 15 amp fuses.
http://www.vikingaircraftengines.com/Wiring%20page.html
I do not like the electrical drawing on the Viking website because there are several
possible points of failure all in series and supplying power to the engine
through only one wire.
I suggested to my friend that he use one of your drawings but he said they were
too complicated. I tried to simplify by removing the E-Bus and E-Bus diode,
while still having a redundant power source for the ignition and fuel pumps
without having always hot wires pass through the firewall. The ignition and fuel
pumps are located on the opposite side (aft) of the firewall from the engine.
If the Alternate Feed Switch is turned on, the engine start circuit is disabled.
This will prevent starting current from flowing through the Alternate Feed
Relay and damaging its contacts. It is intended that the Alternate Feed Switch
be turned on after starting and left on for the remainder of the flight.
My friend prefers circuit breakers even though I recommended fuses. He also wants
to keep weight down by not having a starter contactor.
The Main Bus receives power at each end of the bus. If one connection should
fail, the other will still provide power to the bus.
The engine should keep running with power coming from only the Alternate Feed
Relay or only from Master Contactor or only from the Alternator.
The Viking ECU has two independent (almost) units in one enclosure, although it
only has one wire supplying power. There is no pin-out available for the ECU
37-Pin D-Sub. The only information comes from the Viking website.
The ECU has a SELECT wire that enables one of the two units, depending on whether
the voltage on that wire is high or low. At least that is what I deduced from
the scant information on the Viking website.
The major difference between your excellent drawings and my schematic is that
I have eliminated the E-Bus diode and replaced it with part of the Alternate
Feed switch to prevent starting current from flowing though the Alternate Feed
Relay contacts.
Now, without that E-Bus diode, I am having second thoughts about possible reverse
current due to faults in the starter or alternator circuit.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=376092#376092
Message 11
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Subject: | Re: OBS resolver signals |
On 6/17/12 11:56 PM, AeroElectric-List Digest Server wrote:
> Can anyone explain or point me at any documentation that explains the OBS
> resolver signals for setting the course on a NAV set, e.g. a King 165.
>
> What I know is the the NAV set produces a rounded off square wave at either
> 30HZ or 300HZ. The OBS knob then returns two signals representing the sine
> and the cosine of the position. So for example sine of 90 degrees is 1 and
> cos is zero, sine of 270 degrees is -1 and cos is still 0
>
> What I don't know is whether the returning signals go negative (the older
> CDIs use transformer technology so could easily produce negative voltage) or
> whether they are referenced to the mid point of the excitation signal and
> whether the excitation signal itself goes negative or it just varies between
> 0 and the reference voltage.
If you want to interface with a KX165 you might look at the schematic
of that unit, but the nav radios I'm familiar with (just checked a
couple of older King and Radair schematics) are all capacitor-coupled so
the signal should stay positive with respect to the audio reference
ground. Some CDIs may have a transformer input to prevent ground loops
-- the return side of the transformer would be run back to the nav radio
audio reference ground rather than through the airframe.
A VOR station transmits a reference subcarrier at 9.96 kHz, frequency
modulated with a 30 Hz tone, and amplitude modulation, also of a 30 Hz
tone. The phase angle between the 30 Hz frequency modulation of the
subcarrier, and the 30 Hz amplitude modulation of the main carrier,
corresponds to the angle between north and the direction from the
station to you. The audio input from the nav receiver contains both the
30 Hz AM tone and the 9960 Hz subcarrier with its FM reference
modulation. The CDI or VOR converter demodulates the 9960 Hz carrier so
you now have two 30 Hz tones. The resolver introduces a known phase
shift in the reference; when you turn the OBS knob, you change the
amount of phase shift. The VOR needle is driven by a phase comparator
that measures the phase difference between the 30 Hz variable signal and
the demodulated and phase-shifted 30 Hz reference signal. When the
needle centers, the phase shift is zero because the resolver has
introduced a phase shift equal to the phase difference between the two
30 Hz signals.
Localizer is a different signal entirely but sent on the same wire;
there are two tones, 90 and 150 Hz, and the needle reflects the ratio
between the amplitude of the two tones. When you are on the centerline
of the localizer, you're receiving equal signals from the two sets of
antennas on either side of the centerline, one of which is transmitting
with 90 Hz modulation and the other with 150 Hz.
Message 12
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Hi all
I would like to make a couple of antennas for my Glastar.
Does anyone know what the length is for dipole, or any reason not to "role
my own".
Transponder:
Comm:
Nav:
Marker:
Glide Slope:
UAT:
I will be using Garmin
GTX327
SL30
GMA340
Navworxs ADSB
Thanks in advance for all advice
-Rob Henderson
Message 13
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Subject: | Re: Antenna length |
It is straight forward to figure out the length required from the
frequency of the signal,
velocity = frequency x wave length
so wave length = vel/freq
Using SI units (coz its just easier than imperial)
Velocity = 3 x 10^8 m/s
Freq = 118 to 137 MHz (so centre freq is 126.5 x 10^6 Hz)
So wave length = 3/1.265 m = 2.37m ( about 93 inches)
Most dipoles are half wave, a lot of aircraft antennas are quarter wave.
Wikipedia (or the Aeroelectric connection) can probably explain better
than me - less change of remembering the basic physics wrong!
Peter
On 19/06/2012 21:11, Rob Henderson wrote:
>
> Hi all
>
> I would like to make a couple of antennas for my Glastar.
>
> Does anyone know what the length is for dipole, or any reason not to
> "role my own".
>
> Transponder:
>
> Comm:
>
> Nav:
>
> Marker:
>
> Glide Slope:
>
> UAT:
>
> I will be using Garmin
>
> GTX327
>
> SL30
>
> GMA340
>
> Navworxs ADSB
>
> Thanks in advance for all advice
>
> -Rob Henderson
>
> *
>
>
> *
Message 14
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|
A rough rule of thumb for a free space dipole is:-
299.8/126.5=2.3669m (speed of light divided by the
Frequency)
2.3669 * 0.97=2.2989m (Adjusted for the end effect)
2.2989/2=1.1494m (divide by 2 to make a half
wave
dipole)
1.1494m / 0.0254 (because the US still has
not
converted to metric) (Couldn=92t resist that one )
45.25 inches (but make it slightly
longer maybe 45.5 inches so you can adjust it by trimming equally on
both
sides)
Cut this in two to make the two halves of the dipole and keep the feed
points reasonably close together,
Say around =BD an inch, then check with an SWR meter. (If the lowest SWR
is
below 126.5 mhz then the antenna is trimmed slightly on both ends by say
1/16=94 a time)
And the SWR rechecked.
If you want to make a qtr wave antenna like the Comant Antennas you see
on a
lot of Aircraft then make the Antenna about 22.8 inches long and
Once again trim for desired SWR spread with an SWR meter.
Just remember not to try a use a Dipole inside a Carbon fibre structure
since the Carbon fibre is conducive.
In the end even though I have made many antennas over the years I
decided to
buy Comant Antennas for my RV10.
Cheers
John MacCallum VK2 -GCN
Builder #41016
VH-DUU
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Peter
Pengilly
Sent: Wednesday, 20 June 2012 7:20 AM
Subject: Re: AeroElectric-List: Antenna length
It is straight forward to figure out the length required from the
frequency
of the signal,
velocity = frequency x wave length
so wave length = vel/freq
Using SI units (coz its just easier than imperial)
Velocity = 3 x 10^8 m/s
Freq = 118 to 137 MHz (so centre freq is 126.5 x 10^6 Hz)
So wave length = 3/1.265 m = 2.37m ( about 93 inches)
Most dipoles are half wave, a lot of aircraft antennas are quarter wave.
Wikipedia (or the Aeroelectric connection) can probably explain better
than
me - less change of remembering the basic physics wrong!
Peter
On 19/06/2012 21:11, Rob Henderson wrote:
Hi all
I would like to make a couple of antennas for my Glastar.
Does anyone know what the length is for dipole, or any reason not to
=93role
my own=94.
Transponder:
Comm:
Nav:
Marker:
Glide Slope:
UAT:
I will be using Garmin
GTX327
SL30
GMA340
Navworxs ADSB
Thanks in advance for all advice
-Rob Henderson
Message 15
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Subject: | Re: Antenna length |
Rob,
You should already have Comm I inside your vertical. For our Sportsman we
bought the very economical Bob Archer antennas for our Comm II,
transponder, and marker beacon. When we checked the two Comm antennas for
SWR they measured 1.1 which as far as I know is excellent. The glideslope
antenna is the 5T from Advanced Aircraft Electronics, Inc.
http://www.advancedaircraft.com/, in Alberqurgue which we mounted crossways
just behind Bulkhead A.
Our ADS-B antenna came from:
<http://www.navworx.com/navworx_store/Delta_Pop_Aviation_978_MHz_ADS_B_Ante
nna.html>
Delta Pop Aviation 978 MHz ADS-B
*Antenna*<http://www.navworx.com/navworx_store/Delta_Pop_Aviation_978_MHz_A
DS_B_Antenna.html>
<http://www.navworx.com/navworx_store/Delta_Pop_Aviation_978_MHz_ADS_B_Ante
nna.html>
Dee Whittington
<http://www.navworx.com/navworx_store/Delta_Pop_Aviation_978_MHz_ADS_B_Ante
nna.html>
On Tue, Jun 19, 2012 at 4:11 PM, Rob Henderson <robnrobinh@comcast.net>wrot
e:
> Hi all****
>
> I would like to make a couple of antennas for my Glastar.****
>
> Does anyone know what the length is for dipole, or any reason not to =93r
ole
> my own=94.****
>
> ** **
>
> Transponder:****
>
> Comm:****
>
> Nav:****
>
> Marker:****
>
> Glide Slope:****
>
> UAT:****
>
> ** **
>
> I will be using Garmin****
>
> GTX327****
>
> SL30****
>
> GMA340****
>
> Navworxs ADSB****
>
> Thanks in advance for all advice****
>
> -Rob Henderson****
>
> *
>
===========
===========
===========
===========
> *
>
>
--
DeWitt Whittington
www.VirginiaFlyIn.org
Building Glasair Sportsman with 3 partners
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