Today's Message Index:
----------------------
1. 01:42 AM - Re: Radio Coax (John MacCallum)
2. 05:07 AM - Re: Secrets Techniques (Robert L. Nuckolls, III)
3. 06:54 AM - Re: Ignition Interference (stearman456)
4. 07:27 AM - Re: Ignition Interference (messydeer)
5. 07:40 AM - Re: Ignition Interference (stearman456)
6. 07:47 AM - Re: Radio Coax (paul wilson)
7. 08:53 AM - Re: Ignition Interference (messydeer)
8. 09:37 AM - Re: Shunt insulation (gregmchugh)
Message 1
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Hi Paul,
Coaxial cable can be run next to metal objects and coiled. In fact under
some circumstances coiling it is beneficial, such as if you want to make
a
Transmission line choke Balun, strain relief or water isolation.
You can=92t do that with a Balanced Line Feeder such as the old 300 ohm
TV
ribbon, which may be where the idea of not crossing over
Itself came from.
Sometimes you can get into trouble with odd =BC wave multiples of the
frequency you are working at causing the impedance of the Antenna
and Transmission line together to be something other than it should be.
This
results in a high SWR but this requires a reasonably big miss match
of the Antenna=92s fed point impedance and the Transmission Lines
Characteristic Impedance (50 ohms).
So get yourself an SWR meter, check the SWR and if it=92s less than 2.5
to 1
you will be ok.
Cheers
John MacCallum
VH-DUU
RV10 #41016
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of paul
wilson
Sent: Sunday, 29 April 2012 9:39 PM
Subject: AeroElectric-List: Radio Coax
Is there physics to the comment below?
I happened to pick up the comment on a jeep forum where the guys buy an
antenna with a stock length of coax and don't have the ability to change
the
length.
Apperciate any comments. Thanks, Paul
DO NOT coil your antenna coax lead or let it cross over itself, to get
the
best reception and transmission from your radio. I have now tried this
and
found significant increases for both. Run your lead around the seat,
around
the roof, or whatever you have to do to prevent crossover of the lead,
next
to itself. You will find much improvement in your reception.
Message 2
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| Subject: | Secrets Techniques |
At 06:30 PM 4/29/2012, you wrote:
>Well, that works like a charm!... I've spent so many years trying
>not to melt the insulation that I was not taking full advantage of
>the properties of Tefzel. I've encountered solder sleeves in the
>past, but never appreciate their purpose.
Yeah, they're kinda cool. I'm seeing some po' boy's solder
sleeves showing up from suppliers on the net at attractive
prices. I'm going to acquire some as see how well they
work.
I'm a bit surprised to find them offered to the commercial
installation crowd. PVC or even the higher temperature PVC
insulations are king. Not sure you can put a legacy RayChem
solder sleeve on this wire. But these new kids on the block
just might feature lower temperature solders (yes my children,
there ARE other alloys that will do that melty-glue-thing) along
with some lower temperature shrink and sealants. We'll have
to see.
In any case, I'm pleased that your dragons are at least
"behind bars" if not completely dispatched . . .
Bob . . .
Message 3
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| Subject: | Re: Ignition Interference |
If you have two mags and a filter on each one, the quickest thing to try is swapping
the filters. I had a dud filter once a couple of years ago straight out
of the box.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=372136#372136
Message 4
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| Subject: | Re: Ignition Interference |
There are no filters on either mag. The filter capacitor is on the alternator.
You think putting a filter capacitor on the offending mag wire might work?
--------
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=372140#372140
Message 5
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| Subject: | Re: Ignition Interference |
I put a filter on each of mine (Continental C90 with Bendix mags) and that cleared
up my noise. I had one dud filter at first but after replacing it she's nice
and quiet now.
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=372142#372142
Message 6
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Hi John,
Interesting comments. I will pass them along. I
wondered where the no ant coil vs coil came from.
For my various rigs I use SWRs, cheapy one for CB
and another pricy one for the VHF setups. My SWRs
are great due to my significant effort. I now
have one of Bobs low ohm devices and will work
thru all my grounds and feeds to see what I find.
Should be fun and informative.
I know my discussion was for off road rigs, but I
hope the airplane guys dont mind. Seems applicable to any radio install.
Thanks, Paul
At 02:39 AM 4/30/2012, John MacCallum wrote:
>Hi Paul,
>Coaxial cable can be run next to metal objects
>and coiled. In fact under some circumstances
>coiling it is beneficial, such as if you want to make a
>Transmission line choke Balun, strain relief or water isolation.
>You can=92t do that with a Balanced Line Feeder
>such as the old 300 ohm TV ribbon, which may be
>where the idea of not crossing over
>Itself came from.
>
>Sometimes you can get into trouble with odd =BC
>wave multiples of the frequency you are working
>at causing the impedance of the Antenna
>and Transmission line together to be something
>other than it should be. This results in a high
>SWR but this requires a reasonably big miss match
>of the Antenna=92s fed point impedance and the
>Transmission Lines Characteristic Impedance (50 ohms).
>
>So get yourself an SWR meter, check the SWR and
>if it=92s less than 2.5 to 1 you will be ok.
>
>Cheers
>
>John MacCallum
>VH-DUU
>RV10 #41016
>
>
>From:
>owner-aeroelectric-list-server@matronics.com
>[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of paul
wilson
>Sent: Sunday, 29 April 2012 9:39 PM
>To: aeroelectric-list@matronics.com
>Subject: AeroElectric-List: Radio Coax
>
>Is there physics to the comment below?
>I happened to pick up the comment on a jeep
>forum where the guys buy an antenna with a stock
>length of coax and don't have the ability to change the length.
>Apperciate any comments. Thanks, Paul
>
>DO NOT coil your antenna coax lead or let it
>cross over itself, to get the best reception and
>transmission from your radio. I have now tried
>this and found significant increases for both.
>Run your lead around the seat, around the roof,
>or whatever you have to do to prevent crossover
>of the lead, next to itself. You will find much improvement in your
reception.
>
>
>http://www.matronics.com/Navigator?AeroElectric-List
>
>
>http://forums.matronics.com
>
>
>http://www.matronics.com/contribution
>
>
Message 7
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| Subject: | Re: Ignition Interference |
Yes, thanks for pointing this out. Sounds like I could disconnect the P lead of
the left mag and see if it still makes noise. If it does, then Bob says it's
getting out through the P lead wiring. If that's the case, sounds like replacing
the single conductor wire P lead and ground shield would work. That's not a
huge undertaking, but maybe it could be avoided if I slapped one of my ferrite
beads on the switch end of the offending P lead and ground?
If the noise doesn't go away, then the 'plug harnesses are suspect'
Plug harnesses may be electrically tested (continuity between end of center conductor
and between ends of shield braid). Unhook individual plug wires and do
a continuity check between the spark plug connector shell (attaches to shield)
and engine crankcase.
I don't quite understand what's being asked for, since I don't have a spark plug
wire handy and haven't really looked to see how the wires are made. Sounds like
it's a single conductor shielded wire. Is there to be no continuity between
the inner conductor and the shell?
--------
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=372149#372149
Message 8
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| Subject: | Re: Shunt insulation |
Bob,
They sure look like Weather Pack fuse holders maybe from
http://www.whiteproducts.com/
and the Blue Sea version is on Amazon for $9
http://tinyurl.com/7tzcmc2
Greg
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=372152#372152
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