Today's Message Index:
----------------------
1. 08:53 AM - Re: SL-30 Poor VOR reception (Robert L. Nuckolls, III)
2. 10:33 AM - Re: SL-30 Poor VOR reception (user9253)
3. 11:01 AM - Thanks Bob (Jeff Luckey)
4. 11:12 AM - Re: SL-30 Poor VOR reception (David Lloyd)
5. 12:04 PM - Re: SL-30 Poor VOR reception (Robert L. Nuckolls, III)
6. 12:04 PM - Re: Thanks Bob (Robert L. Nuckolls, III)
7. 12:14 PM - Re: Thanks Bob (j. davis)
8. 12:58 PM - RE-POST: Magneto Noise (Jeff Luckey)
9. 01:13 PM - Re: RE-POST: Magneto Noise (j. davis)
10. 01:13 PM - Re: Thanks Bob (Jeff Luckey)
11. 02:48 PM - Re: Re: SL-30 Poor VOR reception (Kelly McMullen)
Message 1
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Subject: | Re: SL-30 Poor VOR reception |
When the SL-30 was repaired and back in the instrument panel I took
off on a flight to Ocala to check it out. I climbed up to 4500 feet and
watched the OBS and listened for the ID code as I entered the 40 mile radius
of the Ocala VOR. Nothing so I kept going on a course straight for the
station. Around 20-25 miles out I started getting activity on the indicator
but the flags were intermittent and the radio could not maintain a lock.
Finally about 15 miles out the indicators stabilized and the flags stayed
off, obviously something is amiss.
Since the radio has enjoyed a recent bench check,
probability of it being a radio problem is considerably
reduced . . . at the bottom of the list . . .
I have not flown the airplane since but I doubt that lack of a gasket
was causing the poor reception, maybe someone here can tell me.
Agreed . . . gaskets tend to be hedges against
moisture/dirt and have no effect on performance
of any antenna.
The other thing I checked was the
resistance between the center pin and outside barrel of the BNC connector on
the antenna. Resistance was showing basically a dead short (less than 1
ohm, same reading as touching the meter probes together).
40 years ago, this would be uncommon. Nowadays, antenna
designers have deduced value for incorporation of impedance
matching a balancing networks between the antenna element(s)
and the feed line. Further, designing a network with a
DC path to ground is a further improvement for reduction of
noise due to p-static.
This V Dipole encompasses reduced static capability with the use of
P-Stat paint.
A further step forward in the art and science of antennas
for aircraft.
Integral ferrite balun provides for higher radiation efficiency."
Yeah . . . sort of . . . measurable in the lab but
of zero observable significance to the pilot.
I don't know if the construction of the antenna would cause
the meter to show such a low resistance, maybe some here could shed some
light on that.
Yes . . . your observations are not out of the
ordinary . . .
Any ideas, experiences with poor VOR reception here on the list? Since the
radio has been repaired and tested by the factory I'd say it's not the
radio. I checked the connector at the back of the radio tray and it appears
secure so I'm not sure what else to do. Since VORs are being decommissioned
there is going to be less and less need for VOR reception but if I have to
use victor airways during instrument operations I need to have good
reception at the expected range or I won't be able to comply with ATC
clearances. On an side note, a fellow RV-9 builder who is using a simple
flat metal antenna in the wingtip, has no problem receiving the VOR 40 miles
out, and he didn't pay anywhere near what I did for his antenna. Thanks for
the help.
A not uncommon observation. The quest for uber-efficient
antennas on aircraft is problematic. The guys with hammers-
n-saws in the lab can do a fine job of 'optimizing' a
design to textbook ideals but we're not communicating
with space probes or folks with hand-helds over the
horizon.
The nominal signal-to-noise ratios for air-to-ground
contact by radio are huge. For the most part, a "wet-string"
will offer serviceable performance as an antenna.
Do you have access to an antenna analyzer . . .
Emacs!
or perhaps an SWR meter . . .
Emacs!
The FIRST thing to do after checking the obvious (mechanical
connections) is to get some numbers. An antenna analyzer hooked
to the receiver end of the transmission line is the best
way to assess antenna health. Even use of an SWR meter
like the 'red dot' instruments off eBay can be excited with
the ship's comm transceiver (or a hand held) set to
the lowest comm frequency. The SWR should be relatively
low even though you're measuring at the top of it's
design range.
Put a dummy load
http://tinyurl.com/cchp3pf
at the antenna end of your VOR feed line, connect
the feedline to the transceiver and then "talk"
to it while monitoring SWR.
Alternatively, make a temporary connection of your
comm antenna into the VOR receiver input jack and
go fly the airplane. I'm betting that you're going
to see a marked improvement in VOR performance.
If your access to test equipment is limited,
you can play the swaptronics game . . . replace
the connectors on the ends of the feed line just
for the heck of it. It takes less time to do this
simple experiment than all the time spent thus
far looking for 'rate in the woodpile'.
It seems unlikely that the antenna is at fault.
feedline installation errors are a higher
probability.
What ever the problem is . . . it's stone simple
Bob . . .
Message 2
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Subject: | Re: SL-30 Poor VOR reception |
There could be a problem with one of the coax connectors. You could replace the
RG-58 cable with RG-400, which has less signal loss. If the coax is bent with
too small of a radius, that can cause problems. Another concern is the antenna
location. What is the distance between the horizontal stabilizer and the
antenna? This distance can have a big affect on the antenna performance.
Radio Frequency current behaves much differently than DC current. An open circuit
for DC can be a short circuit for RF. And a short circuit for DC can be an
open circuit for RF.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=422373#422373
Message 3
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Bob,
I forgot to say thank you for the magneto trouble-shooting guide you sent a couple
of weeks ago...
So thank you, very helpful
-Jeff
Message 4
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Subject: | Re: SL-30 Poor VOR reception |
Great advice by all concerning this problem . . . .
However, I would not place the fact that the radio just came out of
factory bench testing on the bottom of the problem list.
I have had a few situations where factory repairs were very much less
than acceptable.
The latest was an autopilot recalibration when GPS tracking was not
accurate. Unit came back still with poor tracking. After much arguing
with company, an officer went down to the final bench test and
calibration station and found an error in the factory final test set-up.
Another was a Navigator that had very specific squelch breaks occurring
at odd but, specific frequencies. Turned out the auto squelch factory
test stand was set-up wrong.
I don't understand how such problems can exist in a well respected
company but, it happens.
Let us know what you find with your radio problem. . .
-------------------------------------------------------------------------
-------
----- Original Message -----
From: Robert L. Nuckolls, III
To: aeroelectric-list@matronics.com
Sent: Friday, April 25, 2014 8:52 AM
Subject: Re: AeroElectric-List: SL-30 Poor VOR reception
When the SL-30 was repaired and back in the instrument panel I took
off on a flight to Ocala to check it out. I climbed up to 4500 feet
and
watched the OBS and listened for the ID code as I entered the 40 mile
radius
of the Ocala VOR. Nothing so I kept going on a course straight for the
station. Around 20-25 miles out I started getting activity on the
indicator
but the flags were intermittent and the radio could not maintain a
lock.
Finally about 15 miles out the indicators stabilized and the flags
stayed
off, obviously something is amiss.
Since the radio has enjoyed a recent bench check,
probability of it being a radio problem is considerably
reduced . . . at the bottom of the list . . .
I have not flown the airplane since but I doubt that lack of a gasket
was causing the poor reception, maybe someone here can tell me.
Agreed . . . gaskets tend to be hedges against
moisture/dirt and have no effect on performance
of any antenna.
The other thing I checked was the
resistance between the center pin and outside barrel of the BNC
connector on
the antenna. Resistance was showing basically a dead short (less than
1
ohm, same reading as touching the meter probes together).
40 years ago, this would be uncommon. Nowadays, antenna
designers have deduced value for incorporation of impedance
matching a balancing networks between the antenna element(s)
and the feed line. Further, designing a network with a
DC path to ground is a further improvement for reduction of
noise due to p-static.
This V Dipole encompasses reduced static capability with the use of
P-Stat paint.
A further step forward in the art and science of antennas
for aircraft.
Integral ferrite balun provides for higher radiation efficiency."
Yeah . . . sort of . . . measurable in the lab but
of zero observable significance to the pilot.
I don't know if the construction of the antenna would cause
the meter to show such a low resistance, maybe some here could shed
some
light on that.
Yes . . . your observations are not out of the
ordinary . . .
Any ideas, experiences with poor VOR reception here on the list? Since
the
radio has been repaired and tested by the factory I'd say it's not the
radio. I checked the connector at the back of the radio tray and it
appears
secure so I'm not sure what else to do. Since VORs are being
decommissioned
there is going to be less and less need for VOR reception but if I
have to
use victor airways during instrument operations I need to have good
reception at the expected range or I won't be able to comply with ATC
clearances. On an side note, a fellow RV-9 builder who is using a
simple
flat metal antenna in the wingtip, has no problem receiving the VOR 40
miles
out, and he didn't pay anywhere near what I did for his antenna.
Thanks for
the help.
A not uncommon observation. The quest for uber-efficient
antennas on aircraft is problematic. The guys with hammers-
n-saws in the lab can do a fine job of 'optimizing' a
design to textbook ideals but we're not communicating
with space probes or folks with hand-helds over the
horizon.
The nominal signal-to-noise ratios for air-to-ground
contact by radio are huge. For the most part, a "wet-string"
will offer serviceable performance as an antenna.
Do you have access to an antenna analyzer . . .
or perhaps an SWR meter . . .
The FIRST thing to do after checking the obvious (mechanical
connections) is to get some numbers. An antenna analyzer
hooked
to the receiver end of the transmission line is the best
way to assess antenna health. Even use of an SWR meter
like the 'red dot' instruments off eBay can be excited with
the ship's comm transceiver (or a hand held) set to
the lowest comm frequency. The SWR should be relatively
low even though you're measuring at the top of it's
design range.
Put a dummy load
http://tinyurl.com/cchp3pf
at the antenna end of your VOR feed line, connect
the feedline to the transceiver and then "talk"
to it while monitoring SWR.
Alternatively, make a temporary connection of your
comm antenna into the VOR receiver input jack and
go fly the airplane. I'm betting that you're going
to see a marked improvement in VOR performance.
If your access to test equipment is limited,
you can play the swaptronics game . . . replace
the connectors on the ends of the feed line just
for the heck of it. It takes less time to do this
simple experiment than all the time spent thus
far looking for 'rate in the woodpile'.
It seems unlikely that the antenna is at fault.
feedline installation errors are a higher
probability.
What ever the problem is . . . it's stone simple
Bob . . .
Message 5
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Subject: | Re: SL-30 Poor VOR reception |
At 01:12 PM 4/25/2014, you wrote:
>Great advice by all concerning this problem . . . .
>
>However, I would not place the fact that the radio just came out of
>factory bench testing on the bottom of the problem list.
>
>I have had a few situations where factory repairs were very much
>less than acceptable.
>The latest was an autopilot recalibration when GPS tracking was not
>accurate. Unit came back still with poor tracking. After much
>arguing with company, an officer went down to the final bench test
>and calibration station and found an error in the factory final test set-up.
>Another was a Navigator that had very specific squelch breaks
>occurring at odd but, specific frequencies. Turned out the auto
>squelch factory test stand was set-up wrong.
>I don't understand how such problems can exist in a well respected
>company but, it happens.
>
>Let us know what you find with your radio problem. . .
Another investigative test option is to attach
a VOR/COMM hand held to the antenna feed line
to rule out panel mounted radio problems.
Bob . . .
Message 6
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At 01:00 PM 4/25/2014, you wrote:
>Bob,
>
>I forgot to say thank you for the magneto trouble-shooting guide you
>sent a couple of weeks ago...
>
>So thank you, very helpful
>
>-Jeff
What did you find?
Bob . . .
Message 7
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I'd be interested in seeing that, Jeff. Thanks!
On 25 Apr 2014 14:09, "Jeff Luckey" <jluckey@pacbell.net> wrote:
> Bob,
>
> I forgot to say thank you for the magneto trouble-shooting guide you sent
> a couple of weeks ago...
>
> So thank you, very helpful
>
> -Jeff
>
> *
>
>
> *
>
>
Message 8
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Per request from J. Davis...=0A=0A=0A----- Forwarded Message -----=0AFrom:
"Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>=0ATo: aeroelectri
c-list@matronics.com =0ASent: Tuesday, April 8, 2014 8:06 AM=0ASubject: Re:
AeroElectric-List: Magneto Noise=0A =0A=0A--> AeroElectric-List message po
sted by: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>=0A=0AAt
12:04 PM 4/6/2014, you wrote:=0A=0AI flew w/ a friend recently and when try
ing to get awos for our =0Adestination airport (which is a pretty weak sign
al) it was almost =0Aimpossible to hear due to magneto noise.- The radio
is a Garmin 430W =0Ain a Cherokee and we were around 10 miles from the airp
ort.- When we =0Agot within 3 or 4 miles the signal was much clearer.-
All other =0Atransmissions with ATC & towers were acceptable but I noticed
at high =0Avolume I could clearly hear magneto noise in the background.=0A
=0AI'm wondering if that's just the way it is or if there is a problem =0Aw
ith the magnetos or P lead wiring.=0A=0A- - Was this a new condition or
has it been that=0A- - way 'forever'. It's difficult for the neophyte
=0A- - observer to tell the difference between ignition=0A- - noise
s getting into the system by way of plug wire=0A- - radiation versus p-
lead radiation.=0A=0A- - First, make sure that the perceived noise goes
up=0A- - and down with volume control settings on radio.=0A- - Thi
s all but guarantees that it's coming in through=0A- - the antenna.=0A
=0A- - Then, disconnect both p-leads from the back of the=0A- - mag
netos and run the engine. See if the noise is=0A- - still heard . . . t
urn to unused frequency . . .=0A- - open squelch.=0A=0A- - If you c
an still hear it, then look for bad plug=0A- - wire. If not, hook up on
e p-lead at a time and=0A- - repeat experiment . . . see if noise is pr
edicated=0A- - on either or both of the p-leads being hooked up.=0A=0A
- - Once you've identified the offending radiator,=0A- - you need t
o figure out why. If this is a 'new'=0A- - condition, then you're looki
ng for something that=0A- - has changed. Bad cap in mag (probably not b
oth)=0A- - broken ground lead on p-lead shield. If possible/=0A- -
practical wire p-lead wires per Figure Z-27=0A=0Ahttp://tinyurl.com/n3oy37f
=0A=0A- - Ground p-lead shields at magneto end only . . .=0A- - use
p-lead shields to ground mag switch. Remove=0A- - and existing ground
to the mag switch.=0A=0A- - If the noise is coming from both p-leads,
=0A- - there are 'approved' magneto noise filters=0A=0Ahttp://tinyurl.c
om/l3s4mrj=0A=0A- - that most mechanics will install with a simple=0A
- - log-book entry.=0A=0A- - Bob . . .=0A=0A=0A- Bob . . .-
====================
Message 9
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Subject: | Re: Magneto Noise |
Thanks, Jeff. I was thinking it had to do with ignition issues (rather than
radio noise ) but I'll file it away for future reference.
On 25 Apr 2014 16:08, "Jeff Luckey" <jluckey@pacbell.net> wrote:
> Per request from J. Davis...
>
>
> ----- Forwarded Message -----
> *From:* "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
> *To:* aeroelectric-list@matronics.com
> *Sent:* Tuesday, April 8, 2014 8:06 AM
> *Subject:* Re: AeroElectric-List: Magneto Noise
>
> nuckolls.bob@aeroelectric.com>
>
> At 12:04 PM 4/6/2014, you wrote:
>
> I flew w/ a friend recently and when trying to get awos for our
> destination airport (which is a pretty weak signal) it was almost
> impossible to hear due to magneto noise. The radio is a Garmin 430W
> in a Cherokee and we were around 10 miles from the airport. When we
> got within 3 or 4 miles the signal was much clearer. All other
> transmissions with ATC & towers were acceptable but I noticed at high
> volume I could clearly hear magneto noise in the background.
>
> I'm wondering if that's just the way it is or if there is a problem
> with the magnetos or P lead wiring.
>
> Was this a new condition or has it been that
> way 'forever'. It's difficult for the neophyte
> observer to tell the difference between ignition
> noises getting into the system by way of plug wire
> radiation versus p-lead radiation.
>
> First, make sure that the perceived noise goes up
> and down with volume control settings on radio.
> This all but guarantees that it's coming in through
> the antenna.
>
> Then, disconnect both p-leads from the back of the
> magnetos and run the engine. See if the noise is
> still heard . . . turn to unused frequency . . .
> open squelch.
>
> If you can still hear it, then look for bad plug
> wire. If not, hook up one p-lead at a time and
> repeat experiment . . . see if noise is predicated
> on either or both of the p-leads being hooked up.
>
> Once you've identified the offending radiator,
> you need to figure out why. If this is a 'new'
> condition, then you're looking for something that
> has changed. Bad cap in mag (probably not both)
> broken ground lead on p-lead shield. If possible/
> practical wire p-lead wires per Figure Z-27
>
> http://tinyurl.com/n3oy37f
>
> Ground p-lead shields at magneto end only . . .
> use p-lead shields to ground mag switch. Remove
> and existing ground to the mag switch.
>
> If the noise is coming from both p-leads,
> there are 'approved' magneto noise filters
>
> http://tinyurl.com/l3s4mrj
>
> that most mechanics will install with a simple
> log-book entry.
>
> Bob . . .
>
>
> Bob . . .
>
> >
>
>
> <http://www.matronics.com/Navigator?AeroElectric-List>
>
> *
>
>
> *
>
>
Message 10
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|
At the moment, my findings are inconclusive.- =0A=0AI began the test proc
ess in the run-up area and found that I was not able to reproduce the sympt
oms.=0A=0A1. Engine @ 1800 RPM=0A2. Tune 430 to an unused freq=0A3. Open sq
uelch=0A=0AI did not hear the popping or buzzing sound that I heard a coupl
e of weeks ago in flight (which prompted my original query to the List).=0A
=0A=0AThen Life happened & I have not been able to get back to it - maybe t
his weekend.=0A=0A-Jeff=0A=0A=0A________________________________=0A From: "
Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>=0ATo: aeroelectric
-list@matronics.com =0ASent: Friday, April 25, 2014 12:03 PM=0ASubject: Re:
AeroElectric-List: Thanks Bob=0A =0A=0A--> AeroElectric-List message poste
d by: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>=0A=0AAt 01:
00 PM 4/25/2014, you wrote:=0A>Bob,=0A>=0A>I forgot to say thank you for th
e magneto trouble-shooting guide you =0A>sent a couple of weeks ago...=0A>
=0A>So thank you, very helpful=0A>=0A>-Jeff=0A=0A- What did you find?=0A
- - - - - - - - - - - - -Matt Dralle, List Admin.
====
Message 11
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Subject: | Re: SL-30 Poor VOR reception |
I agree with connector issues. I do NOT agree with cable issues. Ever
since the VOR came on the scene, RG-58 has proved more than adequate on
factory built spam cans. Most have runs of over 20 ft from panel to top
of tail. Often with one or more connectors in the line. I had such on a
Cessna that would easily receive 100nm on H class VOR at 10,000 ft. I
could connect handheld to splitter for same antenna and it also would
receive same 100+ nm range. RG 142 and 400 are better, but not 6 times
better, which is the price difference. I doubt they are even 50% better.
On 4/25/2014 10:32 AM, user9253 wrote:
>
> There could be a problem with one of the coax connectors. You could replace
the RG-58 cable with RG-400, which has less signal loss. If the coax is bent
with too small of a radius, that can cause problems. Another concern is the antenna
location. What is the distance between the horizontal stabilizer and the
antenna? This distance can have a big affect on the antenna performance.
> Radio Frequency current behaves much differently than DC current. An open circuit
for DC can be a short circuit for RF. And a short circuit for DC can be
an open circuit for RF.
> Joe
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=422373#422373
>
>
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