Today's Message Index:
----------------------
1. 08:25 AM - TV Antennas in parallel (user9253)
2. 08:34 AM - Wire too short? Just stretch it a bit... (Dj Merrill)
3. 09:56 AM - Re: RF interference on GRT fuel pressure with PTT (Tim Andres)
4. 10:39 AM - Re: RF interference on GRT fuel pressure with PTT (Robert L. Nuckolls, III)
5. 10:42 AM - FSDO horror shows (Owen Baker)
6. 10:46 AM - Re: TV Antennas in parallel (Sam Marlow)
7. 12:17 PM - Re: TV Antennas in parallel (Harley)
8. 05:02 PM - Re: FSDO horror shows (DVS)
9. 05:42 PM - Re: TV Antennas in parallel (user9253)
10. 05:47 PM - Re: FSDO horror shows (Ed Holyoke)
11. 06:39 PM - Re: TV Antennas in parallel (John MacCallum)
12. 08:18 PM - Re: Fw: Iron-Constantan oil temp gauge (nuckollsr)
13. 10:42 PM - Re: Re: Fw: Iron-Constantan oil temp gauge (Dave Saylor)
Message 1
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| Subject: | TV Antennas in parallel |
This is not aviation related, but may be of interest to electron herders.
Cable is not available at my location. I get TV signals from antennas in the attic.
I read some place that two antennas can be connected together if the feed
lines are of equal length. I took it one step further and connected 3 antennas
together using equal ( 8 foot) lengths of 300 ohm twin-lead TV antenna cable.
The 3 antennas point in different directions. I was surprised to receive
even more stations than I had hoped for, a total of 34 counting the sub-channels,
all with digital quality.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=390745#390745
Message 2
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| Subject: | Wire too short? Just stretch it a bit... |
We've been making the joke for years that if a wire is just a
little bit too short, pull on it and stretch it a little bit to make it fit.
Well, this group took that to a whole new level:
http://news.ncsu.edu/releases/wms-dickey-stretch-wire/
-Dj
--
Dj Merrill - N1JOV - VP EAA Chapter 87
Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Glastar Flyer N866RH - http://deej.net/glastar/
Message 3
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| Subject: | Re: RF interference on GRT fuel pressure with PTT |
Hi Bob
This post from several weeks ago but Id like to revisit it please, I plan to try
to fix this problem soon.
Again the problem is fuel pressure indication spike on transmit from either comm
at the higher end of the band.
The engine monitor connector is a DB-25. My plan is to install the capacitor
listed between the fuel pressure "Aux" input and ground pins inside the
connector if possible using short-as-possible lead length, then a split toroid
on the wire bundle coming into the DB-25connector.
Thanks for any clarification, Tim
________________________________
>
> If it makes you feel better I have the same problem. On mine it only occurs
>when on the upper end of the band, like center frequencies above 130 MHz, and
>happens when I key either the 430W or Icom A210 on those upper frequencies.
> I spoke to Carlos at GRT about this and he suggested the split ferrite that
>you have tried. I have not attempted to fix it yet and was about to ask the
>group what specs I need when I buy it.
> I wonder if a small capacitor could be used to drain off the RF since the
>torrid didn't work. It could be installed inside the D-sub between the fuel
>sensor pin and ground. Can anyone here tell if this might work and if so what
>cap to use?
The value of such capacitors is not so critical
as their construction. A few days ago I published
a capacitors-in-the-connector fix that I crafted
on a Hawker 800 a few years back. See http://tinyurl.com/dxeuj6b
and scroll down to bottom for pictures.
Those capacitor were monolythic ceramics, 0.1 uF
at 50 volts. But probably any value between 0.01
and 0.47 would have worked. What we're interested
in is tiny size so that they can make short lead
connection to the pin and low inductance characteristics
for which the monolythic construction is noted.
Radio Shack used to stock a 0.1 uf cerami (about
1.5 times size of a paper match head). Here's an
exemplar part
http://tinyurl.com/bsk27pw
Ferrites are a whole other ball game. They tend
to improve on an RFI problem with a combination
of two characteristics. (1) they add a lumped
inductance into the wire or wires that are coupling
the energy into the victim (or out of the antagonist).
(2) Ferrites designed for RFI mitigation are TERRIBLE
transformer cores. I.e. they're designed to be
very lossy at the frequencies of interest. By lossy,
we mean that energy coupled into the core is converted
to heat.
BOTH effects are enhanced by the capacitor that
lowers the parallel impedance against which the
series impedance of the ferrite can work. The BEST
ferrite in the world does nothing if the downstream
path to the victim is a high impedance at the
frequency of interest.
This is why the odds are so long that ferrites
alone will fix a problem. The problem would not
have existed had the victim's i/o leads been
designed for that environment in the first place.
So the best moves call for capacitors first with
ferrites stacked on top.
Bob . . .
Message 4
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| Subject: | Re: RF interference on GRT fuel pressure with PTT |
At 11:53 AM 12/20/2012, you wrote:
>Hi Bob
>This post from several weeks ago but Id like to revisit it please, I
>plan to try to fix this problem soon.
>Again the problem is fuel pressure indication spike on transmit from
>either comm at the higher end of the band.
>The engine monitor connector is a DB-25. My plan is to install the
>capacitor listed between the fuel pressure "Aux" input and ground
>pins inside the connector if possible using short-as-possible lead
>length, then a split toroid on the wire bundle coming into the DB-25connector.
>Thanks for any clarification, Tim
Try just the capacitor first. Add only one component
at a time to make sure that you know the benefit of
each. I've had readers report that a whole lot of
"stuff" in an RFI mitigation experiment was "successful"
leaving me wondering how much of that stuff could be
taken out without reducing the degree of success.
Bob . . .
Message 5
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| Subject: | FSDO horror shows |
12/20/2012
Hello Ed Holyoke, You wrote:
=9CA friend of mine was quizzed severely before they would issue
his Repairman's Cert. The thrust was that he hadn't built the plane
himself and was fraudulently applying for the R.C=9D
Why would your friend expect to be issued a Repairman=99s
Certificate for an experimental amateur built aircraft if he had not
built the plane himself? See here:
http://www.faa.gov/aircraft/gen_av/ultralights/amateur_built/repairman_ce
rt/
Thanks,
OC
'O C' Baker says "The best investment you can make is the effort to
gather and understand information."
Message 6
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| Subject: | Re: TV Antennas in parallel |
Where did you purchase your antennas?
user9253 wrote:
>
> This is not aviation related, but may be of interest to electron herders.
> Cable is not available at my location. I get TV signals from antennas in the
attic. I read some place that two antennas can be connected together if the
feed lines are of equal length. I took it one step further and connected 3 antennas
together using equal ( 8 foot) lengths of 300 ohm twin-lead TV antenna
cable. The 3 antennas point in different directions. I was surprised to receive
even more stations than I had hoped for, a total of 34 counting the sub-channels,
all with digital quality.
> Joe
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=390745#390745
>
>
Message 7
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| Subject: | Re: TV Antennas in parallel |
I did the same thing that Joe did, but with only two antennas...I
get 32 channels over the air (again, including the subchannels),
here just south of Rochester NY, most from Rochester, but some of
them from Buffalo.
I didn't buy the antennas, I made them, and mounted them in the
crawl space above my ceiling, pointing North and West (although,
unlike the instructions, I used old wire coat hangars for the
wire, didn't use screws and washers to connect but scraped the
enamel off where contact was needed and soldered them together,
and bent them so the cross wires don't touch...didn't use any
shrink tubing):
www.popularmechanics.com/technology/how-to/tv/build-your-own-digital-tv-antenna
You can also find a number of video instructions to make these on
Youtube. And they do work better than any commercial ones I've
used in the past. I am thinking of dropping Dish Network, as
several of the channels I receive here over the air are also on
Dish (Ion for example)!
Harley
-----------------------------------------------------------------
On 12/20/2012 1:47 PM, Sam Marlow wrote:
> <sam.marlow@roadrunner.com>
>
> Where did you purchase your antennas?
>
> user9253 wrote:
>> <fransew@gmail.com>
>>
>> This is not aviation related, but may be of interest to
>> electron herders.
>> Cable is not available at my location. I get TV signals from
>> antennas in the attic. I read some place that two antennas
>> can be connected together if the feed lines are of equal
>> length. I took it one step further and connected 3 antennas
>> together using equal ( 8 foot) lengths of 300 ohm twin-lead
>> TV antenna cable. The 3 antennas point in different
>> directions. I was surprised to receive even more stations
>> than I had hoped for, a total of 34 counting the sub-channels,
>> all with digital quality.
>> Joe
>>
>> --------
>> Joe Gores
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=390745#390745
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Date: 12/19/12
>
>
Message 8
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| Subject: | FSDO horror shows |
Oc
Read Ed=99s post again. He did not say that his friend did not
build the aircraft. The FAA wanted more proof than is normally
required. The repair cert is in my possession at this time.
dFrom: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Owen
Baker
Sent: Thursday, December 20, 2012 10:42 AM
aeroelectric-list@matronics.com
Subject: AeroElectric-List: FSDO horror shows
12/20/2012
Hello Ed Holyoke, You wrote:
=9CA friend of mine was quizzed severely before they would issue
his Repairman's Cert. The thrust was that he hadn't built the plane
himself and was fraudulently applying for the R.C=9D
Why would your friend expect to be issued a Repairman=99s
Certificate for an experimental amateur built aircraft if he had not
built the plane himself? See here:
http://www.faa.gov/aircraft/gen_av/ultralights/amateur_built/repairman_ce
rt/
Thanks,
OC
'O C' Baker says "The best investment you can make is the effort to
gather and understand information."
Message 9
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| Subject: | Re: TV Antennas in parallel |
> Where did you purchase your antennas?
I do not remember where I bought them. They have been in the attic for years.
Long ago there were 3 sets of lead-in cables connected to a RF A-B-C switch behind
the TV. Now the A-B-C switch is not needed. There is only one lead-in
cable used.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=390764#390764
Message 10
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| Subject: | Re: FSDO horror shows |
No, no, no. He wasn't fraudulently applying for the cert. He built the
plane. They just didn't want to believe him. Said that pictures of him
with tools in his hands and the aircraft under construction could have
been faked. Asked him questions about mechanical stuff on certificated
aircraft as if he was trying to sell himself as an A&P.
Ed
On 12/20/2012 10:42 AM, Owen Baker wrote:
> 12/20/2012
> Hello Ed Holyoke, You wrote:
> *A friend of mine was quizzed severely before they would issue his
> Repairman's Cert. The thrust was that he hadn't built the plane
> himself and was fraudulently applying for the R.C*
> **
> *Why would your friend expect to be issued a Repairmans Certificate
> for an experimental amateur built aircraft if he had not built the
> plane himself? See here:*
> **
> **
> http://www.faa.gov/aircraft/gen_av/ultralights/amateur_built/repairman_cert/
> Thanks,
> OC
> 'O C' Baker says "The best investment you can make is the effort to
> gather and understand information."
> *
>
>
> *
Message 11
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| Subject: | TV Antennas in parallel |
Hi Joe,
That is a good outcome but usually you just can't add antennas in parallel
like that due to Impedance and phasing mismatches.
The feedlines need to be matched to the frequency you are working at and be
either 1/4 wave or 1/2 wavelength multiples depending on
The antenna configuration and not just be equal lengths.
The characteristic feed line impedance in your 300 ohm hook up will be way
off and it will not be 100 ohms as is suggested by simple
Mathematics and as well the impedance will also vary with frequency.
Multipath will cause issues with such a setup and the antennas will have
multiple
lobes and nulls. Being in the attic instead of outside is less than ideal to
boot.
But if it works it works! Just don't expect it to work at other locations
with the same degree of success.
Cheers
John MacCallum
VH-DUU
RV 10 # 41016
VK2GCN
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of user9253
Sent: Friday, 21 December 2012 3:24 AM
Subject: AeroElectric-List: TV Antennas in parallel
This is not aviation related, but may be of interest to electron herders.
Cable is not available at my location. I get TV signals from antennas in
the attic. I read some place that two antennas can be connected together if
the feed lines are of equal length. I took it one step further and
connected 3 antennas together using equal ( 8 foot) lengths of 300 ohm
twin-lead TV antenna cable. The 3 antennas point in different directions.
I was surprised to receive even more stations than I had hoped for, a total
of 34 counting the sub-channels, all with digital quality.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=390745#390745
Message 12
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| Subject: | Re: Fwd: Iron-Constantan oil temp gauge |
Gee Dave. if you'd been sitting out with the rest of the class last time I was
there . . . seriously tho . . . that was some time ago.
Thermocouples are a unique kind of voltage source with a very low source impedance.
I.e. the source impedance is equal to that of the wires which make up the
thermocouple. In the present case, we're talking about type-K (iron-constantan)
wire-couple. See:
www.aeroelectric.com/articles/excerpt.pdf
Those readings sound like resistances from the instrument end of one wire to the
plug washer . . . If you measured beween the two wires at the instrument end,
you would get 10 ohms . . . in the ball park for a properly working thermocouple.
To make ACCURATE low resistance measurements you need something like the
precision low resistance adapter on my website or some similar 4-wire ohmmeter.
In any case, the slightly too-high reading you got is consistent with such lo-ohms
readings at the ends of ordinary test leads.
The thermocouple you have may be repairable. I've fixed a number of them that became
'open' right where the two wires crimp into the plug washer. I trim the
wire back, strip ends, silver-solder together and then tack silver-solder the
junction back onto the tang of the plug washer.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=390768#390768
Message 13
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| Subject: | Re: Fwd: Iron-Constantan oil temp gauge |
What can I say...the old neurons need the rust busted off just like an iron
wire now and then. At least I didn't ask about parasitic junctions--that I
remembered from your seminar, and I use that little tidbit every time we
install the eight to 14 thermocouples on most of the engines we wire.
The thermocouple that failed (the one in the picture) is a probe type that
threads into the oil screen housing.
Once I realized it was terminal, I took it apart. The iron wire was badly
corroded and literally fell out of the probe body onto my workbench.
It was covered with thick red rust.
The other wire was firmly attached inside at the tip of the probe. I don't
see any practical way to reattach an iron wire inside the tube of the probe
so I'm open to suggestions. I'll probably try to find something similar to
replace it.
It's not surprising that the iron corroded. It got a hot/cold cycle on
each engine run, and it was by no means sealed from the atmosphere. On
every warming it drove out the air in the tube and on every cooldown it
pulled in whatever was outside. It took 65 years, but it finally gave up
the ghost.
Dave Saylor
831-750-0284 CL
On Thu, Dec 20, 2012 at 8:17 PM, nuckollsr <bob.nuckolls@aeroelectric.com>wrote:
> bob.nuckolls@aeroelectric.com>
>
> Gee Dave. if you'd been sitting out with the rest of the class last time I
> was there . . . seriously tho . . . that was some time ago.
>
> Thermocouples are a unique kind of voltage source with a very low source
> impedance. I.e. the source impedance is equal to that of the wires which
> make up the thermocouple. In the present case, we're talking about type-K
> (iron-constantan) wire-couple. See:
>
> www.aeroelectric.com/articles/excerpt.pdf
>
> Those readings sound like resistances from the instrument end of one wire
> to the plug washer . . . If you measured beween the two wires at the
> instrument end, you would get 10 ohms . . . in the ball park for a properly
> working thermocouple. To make ACCURATE low resistance measurements you need
> something like the precision low resistance adapter on my website or some
> similar 4-wire ohmmeter.
>
> In any case, the slightly too-high reading you got is consistent with such
> lo-ohms readings at the ends of ordinary test leads.
>
>
> The thermocouple you have may be repairable. I've fixed a number of them
> that became 'open' right where the two wires crimp into the plug washer. I
> trim the wire back, strip ends, silver-solder together and then tack
> silver-solder the junction back onto the tang of the plug washer.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=390768#390768
>
>
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