best antenna

[abcd567]

Why not get a Mac mini and tuck it out of her sight, then once it is set up you can just remote desktop into it as needed from another machine (PC or Mac), it will run happily without a keyboard or monitor attached.
That way she need never know that it is on, they use very little electricity and are happy running 24/7.
Also you could point out to her that frequent switching on and off of electronic devices will generally cause them to fail far sooner than leaving them on as the switch-on surge stresses components far more than anything else.
Ben.

NB my iMac is set to go into power save after 15 mins, it only gets switched off 2-3 times a year!

Raspberry Pi is the way to go for this - Costs Less than an Apple anything.

I agree, BUT can you run VRS or SBS plotter on one ???
I am using a Raspberry for glider tracking, but expecting one to do all the decoding AND plotting is probably not within its capability (however I would be delighted to be proved wrong!)
Second hand Mac minis or re-furbished previous generation units are quite reasonable, just ensure it has a Core-2 Duo or better processor.
Ben.

Thanks Ben & Peter for your valuable advises. I will look to pros/cons & price comparison for "Mac mini vs. Raspberry Pi" setups and decide which way to go. Opinions about this comparison from experienced forum members are most welcomed.

[peterhr]

I agree, BUT can you run VRS or SBS plotter on one ???
I am using a Raspberry for glider tracking, but expecting one to do all the decoding AND plotting is probably not within its capability (however I would be delighted to be proved wrong!)
Second hand Mac minis or re-furbished previous generation units are quite reasonable, just ensure it has a Core-2 Duo or better processor.
Ben.

Apparently you can use it for VRS

[abcd567]

Question: Why my Receiver Range plot by VRS has large number of spikes (sudden drop in range) in various directions?
VRS-receiver range-18hr grab.png

Answer: Large number of buildings, much higher (100 feet to 300 feet) than height of my antenna (65 feet), all around my building.
My own building & 3 adjacent buildings (all 230 feet high), provide the worst obstruction, completely cutting-off 180 degrees of view
See bird's eye view of the area below.


.

[abcd567]

SBSplotter - Another way of plotting receiver range
1. Using jetvision's "RTL-1090" & "SBS Plotter 1" softwares, collect receiver range data for the desired period.
(Click here to Download SBS Plotter 1 - http://jetvision.de/sbs/sbsplotter1.zip)

2. Massage the data using technique described in http://sonicgoose.com/superimpose-po...-google-earth/,

3. Skip the last step of sonicgoose page, and do not create a .kml file for Google Earth by GPS Visualizer site.

4. Instead, plot the range data in Google Map using GPS Visualizer's Map site http://www.gpsvisualizer.com/map_input?form=google. Set the option "Initial Map type" to "Google Street Map", and "Colorize by" to "Track". The map will be produced in a browser window instead of Google Earth.
A screenshot of map produced by me using above method is given below.
SBSplotter-receiver range-18hr grab.png

[SpaxmoidJAm]

don't forget about beaglebone black, if a pi runs out of steam.

Pretty sure what ever you will have to do to get a windows binary running on a Linux platform will have to be done for both a pi and beaglebone and probably not strait forward.

Another alternative that would be easiest as it would be running windows already is one of the NUC based mini PC's. Just google NUC. If you got an older one it wouldnt be that fast or powerful but would be more than enough.
or if your feeling sneaky set the laptops screen saver to a blank screen and colour the LED's in with a marker pen if its quiet enough she might never spot it

[trigger]

We haven't heard much from the "Farnborough" guys recently with their RG402 experiment. Any news?

[F-EGLF1]

We haven't heard much from the "Farnborough" guys recently with their RG402 experiment. Any news?

We haven't gone away, just quite busy at the moment, also the analyser is being used elsewhere, limiting our access to it.
however I did get to try out the prototype on it at the end of last week, it is looking good, but the dip is in the wrong place, I need to shorten all the sections to raise the resonant frequency,
I have masses of photos and when we have worked out the correct element lengths to allow for the effect of the housing I will try to knock up a PDF document with all the details.
Ben.

(Also I have to admit I have spent some time recently playing about with my home-brew 'Open Glider Network' station).

[abcd567]

don't forget about beaglebone black, if a pi runs out of steam.

Pretty sure what ever you will have to do to get a windows binary running on a Linux platform will have to be done for both a pi and beaglebone and probably not strait forward.

Another alternative that would be easiest as it would be running windows already is one of the NUC based mini PC's. Just google NUC. If you got an older one it wouldnt be that fast or powerful but would be more than enough.
or if your feeling sneaky set the laptops screen saver to a blank screen and colour the LED's in with a marker pen if its quiet enough she might never spot it

Thank you SpaxmoidJAm for your valuable advise and contribution to the discussion.

[trigger]

We haven't gone away, just quite busy at the moment, also the analyser is being used elsewhere, limiting our access to it.
however I did get to try out the prototype on it at the end of last week, it is looking good, but the dip is in the wrong place, I need to shorten all the sections to raise the resonant frequency,
I have masses of photos and when we have worked out the correct element lengths to allow for the effect of the housing I will try to knock up a PDF document with all the details.
Ben.

(Also I have to admit I have spent some time recently playing about with my home-brew 'Open Glider Network' station).

Hi Ben,

Just checking Looking forward to your photos.

I had a quick look at Open Glider Network. As we have almost no gliders over here, that is not something I'll be pursuing. Interesting though.

[abcd567]

We haven't gone away, just quite busy at the moment, also the analyser is being used elsewhere, limiting our access to it.
however I did get to try out the prototype on it at the end of last week, it is looking good, but the dip is in the wrong place, I need to shorten all the sections to raise the resonant frequency,
I have masses of photos and when we have worked out the correct element lengths to allow for the effect of the housing I will try to knock up a PDF document with all the details.
Ben.

(Also I have to admit I have spent some time recently playing about with my home-brew 'Open Glider Network' station).

Thanks. Waiting for your feedback/pdf document.
It would be very interesting if another CoCo using commonly available RG6 cable is made & tested.
The comparison of results of tests of CoCos made of RG6 & RG402 will show how much is the advantage of using RG402 over using RG6.
I would love to do this comparison myself, but the only test instruments I have is a multimeter.

[F-EGLF1]

Thanks. Waiting for your feedback/pdf document.
It would be very interesting if another CoCo using commonly available RG6 cable is made & tested.
The comparison of results of tests of CoCos made of RG6 & RG402 will show how much is the advantage of using RG402 over using RG6.
I would love to do this comparison myself, but the only test instruments I have is a multimeter.

I think the main advantage would not be in performance, but more in ease of construction.
With 402 it can be cut to precise lengths with no wispy bits of screening, also because it is PTFE insulated it can be soldered without melting. (The shield is even pre-tinned!)
This should result in a design that is repeatable without needing any expensive test kit, just careful measuring and quite easy soldering.
Ben.

[abcd567]

I think the main advantage would not be in performance, but more in ease of construction.
With 402 it can be cut to precise lengths with no wispy bits of screening, also because it is PTFE insulated it can be soldered without melting. (The shield is even pre-tinned!)
This should result in a design that is repeatable without needing any expensive test kit, just careful measuring and quite easy soldering.
Ben.

Thanks Ben for your reply. I fully agree with you, as this exactly was my opinion. I just wanted to clear this point to many hobbyists who have pinned a high hope on RG402 for an excellent performance (Gain & SWR). The main advantage of RG402 is an easy to construct repeatable design, which can be fairly accurately copied by an amatuer/hobbyist. No VF guessing & no shorts caused by wispy bits of braid wires

[Rooster]

This "is this coax better than the other" discussion is confusing me...
Given that an antenna made from 1m of RG6 costs 7 pence (uk) and one made from RG402 would be 20 pounds... over 25 times the cost!!

my 7p job covers over 150 miles... So why try for more?
plus, we are in a network that has cells way smaller than this....

If its just for kicks, then why not use Andrews heliax? wider bandwidth and costs a load more ;-)

Sent using Tapatalk from my ZX81

[abcd567]

@F-EGLF1
Ben, you were damn right when you said you want to make the coco measurements accurate to fraction of a millimeter level.
I have just run a simulation of an 8-element CoCo (air insulated), which had an element length of 137mm. I varied the length between 134mm and 140mm in steps of 1mm, and results are astonishing! The CoCo is highly intolerant to dimension inaccuracies. Even 1mm error in dimension can make it's performance miserable!

Please see below the screen shots of simulation with element length varying from 134mm to 139 mm.

Image 1 of 2
CoCo 8 elements - Dimension Tolerance 1.png

image 2 of 2
CoCo 8 elements - Dimension Tolerance 2.png

[abcd567]

This "is this coax better than the other" discussion is confusing me...
Given that an antenna made from 1m of RG6 costs 7 pence (uk) and one made from RG402 would be 20 pounds... over 25 times the cost!!

my 7p job covers over 150 miles... So why try for more?
plus, we are in a network that has cells way smaller than this....

If its just for kicks, then why not use Andrews heliax? wider bandwidth and costs a load more ;-)

Sent using Tapatalk from my ZX81

The cable "Andrew Heliax" will make a very sturdy CoCo


Outer Conductor: Copper
Inner Conductor: Copper-Clad Aluminum
Diameter over Jacket, 0.63 inch /16 mm
Diameter over Copper Outer Conductor: 0.55 inch / 14 mm
Diameter Inner Conductor: 0.189 inch / 4.6 mm

Impedance: 50 ± 1 ohms
Maximum Frequency: 8.8 GHz
Foam Dielectric
Velocity Factor: 88%