Airport requires radio. Please suggest inexpensive radio and head set.

[Sam Buchanan]

A quarter-wave whip sure is easier to build and install.......and can barely be seen from a few steps away........

Your Eagle radio really only needs to transmit for a few miles, and transmit distance/readability will be determined by how well your mic can block out wind noise. Much more important that you can receive farther out so you can hear inbound traffic. Matching impedance and all that stuff is to enhance transmit performance, not receive.

[Sparrow]

I agree Sam,  I had watched a lot of Les's videos and had never notice the antenna until it was pointed out to me.

Is there any reason the widest part of the antenna "V" is pointed forward and not to the aft of the fuse?

John L.

[Sam Buchanan]

I agree Sam,  I had watched a lot of Les's videos and had never notice the antenna until it was pointed out to me.

Is there any reason the widest part of the antenna "V" is pointed forward and not to the aft of the fuse?

John L.

It's pointed forward so it can more readily poke out your eye when moving the plane........

Sorry, couldn't resist....I REALLY prefer the quarter-wave whip on the bottom of the plane......the fuse provides plenty of ground plane to make the whip work nicely.

Here is a home-made whip on the bottom of my RV-6:



The antenna on XL-58 is very similar.

[Sparrow]

Thanks Sam,  That is nice too.  I kinda figured the forward or even backward "V" is something one needs to wear safety glasses around.  Since I always wear glasses, no worries.  John L.

[Sam Buchanan]

Thanks Sam,  That is nice too.  I kinda figured the forward or even backward "V" is something one needs to wear safety glasses around.  Since I always wear glasses, no worries.  John L.

Will everyone who wants to take a close look at your plane, especially kids, be wearing glasses???

[Sparrow]

Well Sam that is an interestingg thought.  How does one go about protecting long pointy wires from the inadvertent poke in a vital organ?  The suggested loop on the end may be enough or a large round bead epoxied to the end.  I will certainly be incorporating one of these.

You are employing a whip, so what over all length do I use when employing something like that?  Will it be the length of 1/2 of the "V" employed in the PDF document?  Do you have a suggested source that provides fabrication instructions for the single whip antenna system like you have?  I am assuming you find attaching the antenna to the under side of the fuse is actually a better choice for safety and for antenna efficiency?  Having it located at station 2 or 3 would keep it off the ground and away from inadvertently harming anyone.  What are your thoughts regarding that particular location Sam?  Thank you for your sage advice.  You are correct to advise consideration for young ones and inexperienced ones safety considerations.  Thanks,  John L.

[rockiedog2]

Is your airport the typical non towered unicom airport? if so how can they require a radio?
it would seem like they could more like "request" that you have one. do they also have a requirement that you use it? if so that seems to take away the authority of the PIC.
years ago this bunch on the airport commission here stuck out their chest and announced that the time had come to make ebody get a radio. i asked a number of questions about that among them was who's gonna pay for it and how are you gonna enforce that cause i wasn't gonna comply. that was the end of it.
i got nothing against using a radio but i don't want to be told i gotta go above and beyond the FARs cause of somebody's opinion.
but maybe your airport is some sort of special case.

[Sparrow]

Hi Joe,
Hope U R having fun.  I have enjoyed your recentt vids.  Well, the airport is owned by Virginia Tech and is considered an executive airport used by the rich with twin, or better, jet engines on each side of the tail.  The jets typically take a straight in approach and announce their intention via radio.  I certainly don't desire to get in their way when they come screaming in.  They have made concessions for me to park my vehicle there to use the facility.  That in itself is worth something and I appreciate their accommodation.  I would rather travel 2.5 miles to fly than over 18 miles to Dublin.  I have found that in this town Tec gets what Tec wants. 

John L.

[rockiedog2]

>>>owned by Virginia Tech

yeah i'd get a radio too. private field...and they would run you off if you didnt wouldnt they. not good...

we dont have many rules here at spencer field

[Sparrow]

Just an update on what I have decided to do based on the following:

Well, we lost power this morning at 1AM.  I got up and did the power switch over and cranked up my backup generator to keep all items in the home running.  I couldn't sleep after that excitement so I started searching the net for all the various information sorces regarding the antennas.  Based on the information I was able to gather I am going to do the following for the reasons indicated:

1)  I will build the dipole and mount it vertically and have it facing toward the aft of the fuse.  The dipole has a 2db gain, the signal strength pattern is more advantageous for vertical mounting and I like the point of the dipole "V" to be facing into the wind.  I have opted away from a single 1/4 wave whip antenna because the lack of a substantial ground plane will make the dipole an advantage.  Putting the 1/4 wave whip under an aluminum surface having dimensions equivalent to 20" x 30" or greater makes that particular arrangement suitable.  Supporting the decision is also a quote from the patent application in 1898 of Sir Oliver Joseph Lodge:

 "...As charged surfaces... I prefer, for the purpose of combining low resistance with great electrostatic capacity, cones or triangles or other such diverging surfaces with the vertices adjoining and their larger areas spreading out into space..."

2)  I have chosen to deviate from the assembly PDF by changing the use of the 1/4 wave Pawsey stub balun and use a 1:1 coaxial cable balun.  The reasoning here is the comparison of the two, based on reliable experimental data, shows the 1:1 coaxial cable balun is not influenced by its proximity to conducting elements in its proximity as the Pawsey stub balun is.  The magnetic field of the Pawsey is carried in the braided jacket and this makes it susceptible to any conducting influences.  The 1:1 cable coaxial balun carries its magnetic field on the internal conductor and is therefore not influenced by the proximity to outside influences.

The absence of cap hats or coronal ball on the end of the antenna elements will contribute to static noise that manifests as pops when heard.  The suggestion is to utilize a 1" ball on the end of the antenna and the ball will have no protruding sharp edged elements that will cause a concentration of a static charge.  The link that talks about this is:  http://www.k0bg.com/static.html
I will be employing some type of antenna termination that will, hopefully, reduce the amount of static charge concentration on my antenna system.

There exists additional questions regarding the reported influence of the spark ignitions electromagnetic on the radio system.  I wonder about the Pawsey stubs susceptibility and if the overall system would be improved by applying a balun that is less susceptible to outside elements.  I intend to look closer at this particular aspect of the system soon.

I have attached the experimental PDF that compared the susceptibility of the two baluns and the testing of when to employ speed of light correction factors in calculations and not.

Once built and deployed, if the group desires, I will inform as to the results.  This will most likely be sometime in January 2015.  Addressing any spark ignition negative influence will not be possible until the engine is in place and operating.

IMO

John L.

[Sparrow]

Hay Joe,
I love your setup and field.  I fully intend to show up at your patch some day and pitch a tent next to Woodstock, if you are game.

The manager of the airport kind of had to allow me, with the radio reservation, because the Blacksburg Police Department has their powered paraglider in a trailer at the field inside the security fence.  That pretty much clinched allowing me to do something similar since the precedent had been set.  There is a charge of $45 per month for keeping a trailer on the property and carry an umbrella policy of $1 million liability.  I am working on designing a trailer that will hold Woodstock and allow me to assemble him in 30 minutes or less when I arrive at the field.  That is for another thread.  A Mr. Cecil McBride established the Blacksburg Flying club in 1965 and he called me yesterday.  He is very interested in the UL side of things.  He was totally unaware of the FAR103 regs and what constitutes a UL.  He asked for Woodstock's dimensions and weights and was truly amazed by the design and the safety the design inherently contains.  We talked about the cost of flying in GA.  He was a corporate jet pilot for many years and he owned a Piper Cub way back.  He said the flying club started with an Aeronca Champ.  He clearly stated that he truly wants a low and slow again experience that just isn't available in a jet.  His concern was the cost of a cub at this time exceeding $33K for the most inexpensive one he could find.  Yep, he is long in the tooth and a great guy.  I told him I would love to get some type of UL building and flying program going to increase the interest and footprint of the sport in this place.  I am awaiting his answer.  He does like the operating cost of the UL compared to the current $90 plus per hour in a Cessna 172 that is owned by the club.  I have time on my hands and I would be more than willing to offer my time to anyone that may want to get started.  I am barely started but I have lots of engineering and practical machinery and manufacturing experience under my old belt.  I love flying and I want to share.

Well, off topic but I hope of interest.

Thanks to all of you.

John L.

[Sam Buchanan]

Well Sam that is an interestingg thought.  How does one go about protecting long pointy wires from the inadvertent poke in a vital organ?  The suggested loop on the end may be enough or a large round bead epoxied to the end.  I will certainly be incorporating one of these.

You are employing a whip, so what over all length do I use when employing something like that?  Will it be the length of 1/2 of the "V" employed in the PDF document?  Do you have a suggested source that provides fabrication instructions for the single whip antenna system like you have?  I am assuming you find attaching the antenna to the under side of the fuse is actually a better choice for safety and for antenna efficiency?  Having it located at station 2 or 3 would keep it off the ground and away from inadvertently harming anyone.  What are your thoughts regarding that particular location Sam?  Thank you for your sage advice.  You are correct to advise consideration for young ones and inexperienced ones safety considerations.  Thanks,  John L.

John,

You appear to be committed to the dipole in spite of its complexities and the dubious advantages over a whip for our application. But you asked some questions so I took some photos at the airport this morning to address some of them.

In one of my earlier replies to your inquiries (reply #1 of this thread) I referenced how to build a simple whip like I had on my RV-6, but maybe you missed it. Scroll about 1/2 way down the page to see a 1/4 wave whip made out of a PL-259 coax connector and stainless welding rod:

http://home.hiwaay.net/~sbuc/journal/tracker.htm

But the antenna on XL-58 is even simpler and works just as well. Here it is:



Yes, the length is the same as one element on the dipole, about 23.5".

Here is how it is mounted and fed:



Don't git no simpler than this!  

The antenna is merely a rod (mine is aluminum) that is threaded on one end for the nuts. The adel clamp insulates the element from the airframe and the coax braid is connected to the airframe.

Try it...you will like it.  

(P.S. You are waaaay over-thinking this.....)  

[Sparrow]

Hi Sam,
Thank you for your time and work to keep me on the straight and simple.

I see what you have done and I must admit it is simple compared to the dipole.

I have all the information now and I always reserve the right to change my mind.  That is called, "Getting in touch with my feminine side.".

I have decided to go with the 1/4 wave whip that you devised and I will be testing it for clarity and range.  If it suits me, enough said and done.  If I find I am needing additional I will employ the dipole solution.  It is nice to have options.

I am driven to understanding all my life.  The last project I carried out when in industry was to design, test, build and test again a measuring machine that inspected 1/2 shell engine bearings that were classified into 5 classes in 3 micron class sizes.  Now, 3 microns is the equivalent of 3 standard bacteria holding hands.  The machine, as do all machines in a + - 6 sigma statistically capable environment demonstrate the ability to statistically not allow a bad part get past it at the rate of no more than 6 in a million.  When you are measuring 74 bearings a minute at this level of accuracy, everything that you can imagine will kick you in the teeth.  People talk about a micron like it is a country mile.  You can't see 3 microns and we are selectively fitting engine bearings in an automated process to achieve 0.0003" oil film thicknesses.  That is why the oil viscosities have gotten down to 5w-20 and 0w-20.  If you use oils with higher viscosities, the bearing will be starved and metal to metal contact will occur.  The new engines have less harshness and noise because the smaller clearances actually create increased supporting strength and vastly reduce noise due to excessive oil film clearances. The reduction of viscosity increases the percentage of energy actually transferred to the drive wheels and reduces the viscous sheer losses due to higher oil viscosities used in the past.  More miles per gallon of fuel is now achievable.   So, where I have been sitting, I am just giving things a cursory overview. 

I do reserve the right to add a corona ball on the end of the whip, if needed. 

Truly, I do appreciate your guidance regarding this.  I like the fact that there are options and opinions and many things and ways
 to skin a c a t.   Some pull the skin off with brute force and others use a scrimshaw blade and lightly undress the beast.
Did you know this site will not let one type "Skin a cat."  remove the spaces between C A T.  It did it again.  It removed the feline name after the "a".  That is funny.
I like the best opportunity for success the first time out.

Thanks to all,

John L.

[Sparrow]

Hi Sam,

I like the pictures.  My floor is a  SS sheet.  This should enhance the back plane to some degree. 

I forgot to ask if you have experienced any ignition noise with this setup?  If you did, what measures were required to correct the issue?

Thanks again.

Send the consulting bill to Joe. 


John L.

[Sam Buchanan]

Hi Sam,

I like the pictures.  My floor is a  SS sheet.  This should enhance the back plane to some degree.  

I forgot to ask if you have experienced any ignition noise with this setup?  If you did, what measures were required to correct the issue?

Thanks again.

Send the consulting bill to Joe.  


John L.

Aha! The stainless floorboard is the perfect ground plane for the whip antenna, doesn't get any better than that. Mount the whip in the center of the floorboard and you will have an optimum antenna that satisfies all antennae criteria.

Yes, there is some ignition noise, but that isn't due to the antenna. The magneto wiring harness is unshielded so we do the best we can. The inexpensive handheld transceivers don't have as much noise rejection as a good panel-mount COM radio.