Today's Message Index:
----------------------
1. 03:32 PM - Some experiments fail (Ernest Christley)
2. 05:24 PM - Re: Some experiments fail (Ed Anderson)
3. 06:50 PM - Re: FW: S704 Relay Wire Sizing (Ken)
4. 07:18 PM - Re: Some experiments fail (Bill Boyd)
5. 07:32 PM - Re: Some experiments fail (Gilles Thesee)
6. 10:32 PM - Voltage Across Open Batt Contactor (PIAVIS)
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 |
|
| Subject: | Some experiments fail |
Some ideas look good, until you try to implement them. Like using the
pitot tube for an antennae. It's worth a shot, right? There's even
some documentation of the technique at
http://contrails.free.fr/instruments_ant_sonex.php
Pictures of my attempt are at
http://ernest.isa-geek.org/Delta/Pictures/PitotAntennae1.jpg
and
http://ernest.isa-geek.org/Delta/Pictures/PitotAntennae2.jpg
I was able to borrow a "MFJ HF/VHF SWR Analyzer, Model MFJ-259B", do a
sweep from 110 to 140 MHz. A few readings are:
MHz SWR R X
110 15.4 20 81
115 20.2 2 21
120 14.9 3 1
125 10.8 14 47
130 8.6 403 0 (lowest SWR)
135 14.4 9 72
140 18.6 3 25
I didn't think I could get much below an SWR of 2.5 or so, and was
willing to accept the resulting poor performance; but, 8.6 is really
high. But then I put the rubber ducky antennae from my handheld scanner
on the instrument. Everything in the aviation band was ">25", ie out of
the instruments range. It dropped into range at 130MHz and to 1.6 at 149.5.
Considering that the handheld scanner seems to work, how viable would an
SWR of 10 to 20 work over here on the crowded eastern seaboard for
mostly day VFR operations?
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 |
|
| Subject: | Re: Some experiments fail |
Gee Ernest, being an old Ham radio operator, I would be horrified to see
anything higher than 2 SWR on my antennas {:>) But, don't have any idea how
it would affect aircraft air ground comms.
Ed
----- Original Message -----
From: "Ernest Christley" <echristley@nc.rr.com>
Sent: Friday, December 22, 2006 6:28 PM
Subject: AeroElectric-List: Some experiments fail
> <echristley@nc.rr.com>
>
> Some ideas look good, until you try to implement them. Like using the
> pitot tube for an antennae. It's worth a shot, right? There's even some
> documentation of the technique at
> http://contrails.free.fr/instruments_ant_sonex.php
>
> Pictures of my attempt are at
> http://ernest.isa-geek.org/Delta/Pictures/PitotAntennae1.jpg
> and
> http://ernest.isa-geek.org/Delta/Pictures/PitotAntennae2.jpg
>
> I was able to borrow a "MFJ HF/VHF SWR Analyzer, Model MFJ-259B", do a
> sweep from 110 to 140 MHz. A few readings are:
>
> MHz SWR R X
> 110 15.4 20 81
> 115 20.2 2 21
> 120 14.9 3 1
> 125 10.8 14 47
> 130 8.6 403 0 (lowest SWR)
> 135 14.4 9 72
> 140 18.6 3 25
>
>
> I didn't think I could get much below an SWR of 2.5 or so, and was willing
> to accept the resulting poor performance; but, 8.6 is really high. But
> then I put the rubber ducky antennae from my handheld scanner on the
> instrument. Everything in the aviation band was ">25", ie out of the
> instruments range. It dropped into range at 130MHz and to 1.6 at 149.5.
>
> Considering that the handheld scanner seems to work, how viable would an
> SWR of 10 to 20 work over here on the crowded eastern seaboard for mostly
> day VFR operations?
>
>
>
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: FW: S704 Relay Wire Sizing |
Hi Jim
Yes I agree with you. Since the coil circuit has a 5 amp CB in it I
think you could go all the way down to 22awg if you wanted.
I also think that 12awg is appropriate for the 20 amp alternator but
overkill for an 8 amp unit.
Ken
PIAVIS wrote:
> In sizing wires per the Z-13 diagram on the S704 relay for the SD-8,
> most of the wires supporting the SD-8 are 12AWG. For the jumper from
> the + side of the contactor on the relay, to the COM tab, can I use
> something as low as an 18 or 20 AWG wire for this, Im not sure of the
> current flow through this. Based on other posts on the subject,
> theres only about .1A on the line from the contactor ground tab
> through to the breaker and switch, so I should be able to go to a much
> smaller wire here.
>
> Thanks,
>
> Jim
>
> -7
>
> Redmond, WA
>
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: Some experiments fail |
what kind of impedance matching schemes did you try?
The angle between the antenna and ground pigtails in the picture looks
really narrow for best results. What sort of ground are you working
against?
Maybe a better approach would be to engineer a suitable antenna, then
hollow it out to act as a pitot, versus designing a pitot and then
trying to match it electrically to a transmitter.
-Bill B.
On 12/22/06, Ernest Christley <echristley@nc.rr.com> wrote:
>
> Some ideas look good, until you try to implement them. Like using the
> pitot tube for an antennae. It's worth a shot, right? There's even
> some documentation of the technique at
> http://contrails.free.fr/instruments_ant_sonex.php
>
> Pictures of my attempt are at
> http://ernest.isa-geek.org/Delta/Pictures/PitotAntennae1.jpg
> and
> http://ernest.isa-geek.org/Delta/Pictures/PitotAntennae2.jpg
>
> I was able to borrow a "MFJ HF/VHF SWR Analyzer, Model MFJ-259B", do a
> sweep from 110 to 140 MHz. A few readings are:
>
> MHz SWR R X
> 110 15.4 20 81
> 115 20.2 2 21
> 120 14.9 3 1
> 125 10.8 14 47
> 130 8.6 403 0 (lowest SWR)
> 135 14.4 9 72
> 140 18.6 3 25
>
>
> I didn't think I could get much below an SWR of 2.5 or so, and was
> willing to accept the resulting poor performance; but, 8.6 is really
> high. But then I put the rubber ducky antennae from my handheld scanner
> on the instrument. Everything in the aviation band was ">25", ie out of
> the instruments range. It dropped into range at 130MHz and to 1.6 at 149.5.
>
> Considering that the handheld scanner seems to work, how viable would an
> SWR of 10 to 20 work over here on the crowded eastern seaboard for
> mostly day VFR operations?
>
>
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 |
|
| Subject: | Re: Some experiments fail |
>
> Maybe a better approach would be to engineer a suitable antenna, then
> hollow it out to act as a pitot,
Hi all,
In my buddy's article at
http://contrails.free.fr/instruments_ant_sonex.php, he says he designed
the antenna out of an aluminum tube, and matched it to the particular
form of the vertical fin, acting as a ground plane.
He as not flown yet, and advises to wait for real world tests.
Season's greetings to all,
Best regards,
Gilles
http://contrails.free.fr
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 |
|
| Subject: | Voltage Across Open Batt Contactor |
After connecting the battery contactor per Z-13, is it common to have about
.04 V across the contactor when open? I'm sure I'll have plenty of basic
Electrical 101 questions as this is sure my weak area on this RV so far. But
I'm learning!
Jim
-7
Redmond, WA
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! --
|