Tulsa Tech Net for 10/8/10

The subject is antennas

I'm sure to those that have noticed that I'm having a time keeping up on the blog !!!
The tech net started with me having some mic troubles and i got them resolved. Then Clarence, AE5UB, was wanting some help on choosing a directional array for 6 and 10 meters. I suggested a rotatable dipole for 6 meters. One issue that was brought up is antenna regulations for being in the vicinity of an airport. If anybody has a link to this info please send me a line so I can post it. Multi-band quad was also brought up as an option and there are many plans for multi-band quads on the internet. There was also metion for the log periodic antenna for multi-band use. The Log Periodic is an array that consist of multiple dipoles to cover a wide range of frequency's. The look similar in construction the the old vhf television arrays that everyone had on their house until the mid 90's. As you change frequency the active region shifts along the array.

The windom is a dipole that is commonly used for multi band use. It is an off-center fed dipole. At certain bands and a certain distance that the dipole is fed off center there comes a point that the feed point impedance will be the same . Then the dipole is fed with an impedance transforming balun to bring that high impedance down to 50 ohm.

Tim, KF5FSJ, had an oddity about pouring water at the base of the push-up pole of his 2 meter beam to cure some performance issues he was having.

Dave, NB5B, Is putting up a digipeater in Manford to bring APRS coverage to that area.

Thanks to all that participated and it was a good turnout being that the football game was on.

here is a link to the MP3 of the net to save it right click on the link and click Save Link
http://www.w5bbs.us/?file_id=11

The Grid Dip Meter

The Grid Dip Meter

The grid dip meter also known as a grid dip oscillator is variable oscillator circuit that uses a variable capacitor for tuning and external coil for the L part of the circuit. Most also have a potentiometer to control the level of oscillation of the circuit. The value of the coil determines the frequency range of the meter and most meters come with a set of coils that are calibrated to the frequency dial on the meter. The actual values of the coils is not critical if you have a receiver with a calibrated readout on it to compare to. The indicator meter on the unit measures the grid current in the circuit and is what is used to make measurements. You can find used meters at hamfest and swap meets in the price ranging from $5 to $50 depending if they have the coils and the quality and condition of the meter

Well the grid dip meter is used to check the resonant frequency of a tuned circuit whether that circuit be a pi-network in an amplifier or a filter or the most common an antenna. How this is accomplished is that rf energy is coupled into the circuit under test and you vary the frequency of the oscillator in the meter until resonance is found. At the point of resonance the circuit will absorb the most rf from the meter much like an antenna will take rf from a transmitter that is matched. Once this happens the grid current of the tube in the oscillator will drop thus the "dip".

If you want to know the value of that inductor or coil you just wound then you can use the meter and a little math to do that. What you would do is take a high quality capacitor of known value and put it in parallel with the unknown inductor and now you have a tuned circuit. Then you just take your meter and find the resonate frequency of that circuit. Now you have a lot of info now what? Well here's the formula to find the inductance of that coil in uH.
.............1
L=--------------------
..........4π2 f2 C

π=3.1416
f is in MHz
C is in uF
L= unknown in uH

The same thing can be done with a known inductor for capacitance and the formula is the same but reverse value C and L in the formula.

You can find the Q of an inductor and here's how to do it:
Find resonance of the industor then tune lower and then higher until the dip is reduced by 30%. When you go higher this is F1 and then lower is F2 and the formula is as follows....

.........F
Q=------------
......F1 - F2

and that Q!!!!!!

Here's a link to follow along with on tonites net

http://g4rvh.files.wordpress.com/2008/08/waht-you-can-do-with-a-dip-meter.pdf

The Tech Net Is Back!!!!!

Well its been a while but the Tech Net is back!!


Last week 9/24/10 was the first net in a while and we had just a handful of check-ins but overall I think that it went well. We had Tim KF5FSJ ask about how to tune in a psk-31 signal and Dan KF5HYD talked antennas and I recomended that he put his dipole for 10m in a vertical configuration to help him work local stations. Also I am in the process of getting some specs on a roll-up J-pole made from 450ohm ladder line that would be great for a go box.



Curtis KC0FHF was looking for a good base antenna ideas for 2m local repeater work and he mentioned an antenna that he used to run that he enjoyed. It was described simular to a discone but with solid cones for the groundplanes. I said that I would try to look up the manufacturer and model number for him and i ran across it in an ad in the Sept. 1995 issue of QST when i was looking for plans for a 2m quad that i was refered to. Still havent found the plans but the Ant was an IsoPole144 made by Spectral Antennas. The wbesite is http://www.isopole.com/



I realy enjoyed running the net and i will try my best make sure its held on a weekly basis. I send many thanks to Don KE5OMV for starting this net that our community has needed for a long time and his support in helping me continue it.

The Topic for the next net is GRID DIP METERS! I look forward to the next net and until then keep the solder flowing and the RF going.

Travis
KD5UND

Rain Gutter Antennas

http://www.sgcworld.com/raingutterinstall.html

Green Country Hamfest Prizes

March 12th and 13th - Claremore, OK
http://www.greencountryhamfest.org

GRAND PRIZE Elecraft K3 160M - 6M Tranceiver
2nd Prize - Yaesu FT 897D
3rd Prize - Yaesu FT 8800R
Hourly prizes - Yaesu VX-3R (Must be present to win)

Tech Net Notes January 29, 2010

Loop Antennas

nb5b, Dave, (I believe it was) mentioned that he was thinking about putting up a loop antenna and suggested Loop Antennas as a topic several weeks ago. Having been intrigued with the loop antenna concept for some time, I was very interested in pursuing that topic when I had a chance. That chance came with the January 29th, 2010 Tech Net.

I received the following information from: http://www.bloomington.in.us/~wh2t/loop.html

From WH2T - Dr. Ace's Full Wave Loop Antenna Info

"I have personally used a 160 meter band Horizontal Full Wave Loop antenna with very good success. I worked all 50 states and several countries with 100 Watts using the antenna on the 160 meter band. With a good antenna tuner, the antenna will work 6 thru 160 meters. I currently use a 75 meter Full Wave Delta Loop on the 6 thru 75 meter bands with a tuner. I am very pleased with it."

He goes on to mention that on horizontal polarization he gets about 2.1 dB gain.
He claims the loop is:
Much quieter than a dipole or vertical
Has a broader bandwidth
Usually outperforms a dipole antenna

He feeds his with 75 ohm coax but says 50 ohm can be used.

Dimensions: The formula is 1005/Freq in Mhz = Length in feet
160 Meters at 1.9 Mhz = 529 ft.
75 Meters at 3.85 = 261 ft.

Trimming may be necessary to obtain a low VSWR.

The impedance of a Full Wave Loop is theoretically in the vicinity of 100 ohms.

Connect the center conductor of the coax to one end of the wire and the shield to the other end. Be certain to seal the shield end to protect against water. \

Any shape will work - square, octagon, pentagon, triangle (delta loop), or circle. "The larger the area or aperture inside the loop, the better. A circle has the largest area but is impractical. If you use a triangle shape try to make each leg an equal length as this gives the largest inside aperture or area."

"Note 1 - Don't use a Balun on this Antenna! On a horizontally oriented loop you can feed a corner, center of a side or anywhere. It is unimportant."

"Note 2 - If you know you will be using a Loop, Dipole, Zepp, etc. on Multiple Bands and you want the most efficient performance of the antenna system you will always get less feedline loss if you use Open wire 450-600 Ohm window/ladder line."

"If you feed the Full wave loop antenna direct with a single piece of coax you can only adjust add/prune the antenna til the VSWR gets down to about 1.7:1 at resonance, so you will probably want to use a tuner if you want to cover an entire HF band.. And yes the tuner will work fine as long as you are not using a linear amplifier."

In the article he also includes information on how to determine the length of the feedline using a combination of 75 ohm and 50 ohm coax.

With that we began the net.

kd5avk, Harold, on his mobile from Greenwood, Arkansas, asked if a turner was needed with a loop. After looking back at the information from WH2T it was determined that yes, a loop is needed if using the antenna multiband. Otherwise the antenna will work best only for the frequency for which it is cut.

ae5mn, Hank, asked if the loop antenna can be strung aroung gutters, downspouts and etc. Having installed a myster antenna around the eves of my house with good results, I relayed that I had kept the elements of the dipole in the middle of the eve which was at a minimum the recommended 5 1/2 inches away from most metal objects (including gutters, downspouts, cable TV wiring, and AC service wiring.

kc5zqm, Doug, mentioned that he had used 2 Meter loops for fox hunts and tracking balloon beacons with kc5trb, Harry. In those instances he's used them mostly in the vertical orientation. He mentioned that in SSb mode the horizontal orientation would more likely be used.

k5bbm, Brian mentioned that the loop antenna that kc5zqm referred to may be able to be found at arrowantenna.com.

kf5if, Wade, mentioned a 40 meter Delta Loop that he and the late ae5ft, Gene built at a field day that had a 40 ft peak. The broadsides were to the North and South and that is where they made most of their contacts. It was bottom fed, near the center. No turner was used and SWR was below 2:1 across the band. He mentioned that he was a little disappointed in the amount of noise he had on it and that the high noise may have been due to the vertical orientation and it being in the heat of summer. He did not use an analyzer during the construction, but did use an analyzer afterward to confirm it's characteristics.

End of Net

Tech Net Notes December 10, 2009

We had a very short net on this evening. No questions (until the end) and very few comments.

ke5cub, Lee, made the announcement that he has a CD full of Ham Radio manuals that go back to 1928. If anyone needs a manual for an older radio, Lee will run you off a copy for no charge. If you can reimburse Lee for his ink/paper expenses, that's fine, but not required or expected.

If you have a need for a manual for a piece of ham gear, contact Lee, ke5cub, by phone at 245-0788, or by email at ke5cub@cox.net.

kk5edd, Ed, checked in and said he's trying to decide between an auto tuner and a manual tuner. He would like to know what the pros and cons are. Especially he's interested in folks who may have found advantages of one over the other. This will probably be a topic for our next TARC Net, January 29th.

See you on Wednesday, January 13th!

Tech Net Notes November 27, 2009

After enjoying Thanksgiving Day, and it being a holiday weekend for many, we convened the November, last-Friday-of-the-month, Tech Net on TARC's repeater system at 9:00 PM.

kd5und, Travis, checked in with a problem he's been having with a hum in his radio only when he uses an electret mic. When he changes to a dynamic mic, the hum goes away. When he changes radios, but keeps the electret mic plugged in, the hum is there. He's checked his grounding, changed power supplies, checked his mic shield and tried other radios and had narrowed it down to a problem with the electret type microphones only. Since it happens with other electret microphones, it probably not a problem with the microphones. When the hum is there and he places his finger on the radio chassis, the hum goes away. So the question is "What is the microphone picking up, and from where, and how can it be corrected?"

kd5und, Travis, also mentioned that he's got fork lift batteries for his back-up power and is using a UPS charging circuit out of an old APC unit (with bad batteries) to keep them charged up.

wb5mxo, Guy, checked in and mentioned a w3ff BuddiPole he saw mounted on a three wheeled bicycle. This was in response to an earlier e-mail communique.

n5kh, Will, suggested to kd5und, that he try lifting the ground pin to the AC house wiring to see if there was something coming in on the ground.

ke5wph, Andrew, said that he's getting prepared to put in a 45 ft. Rohn 25 tower and has a question, "What is the optimal guy tension for the guy wires. Regarding Travis' problem. Maybe an RF choke on both positive and negative.

kd5und, Travis, suggested to ke5wph that he tighten his guys to 3 - 6 inches of deflection on the guy cable.

n5kh, Will, mentioned an RF choke as well. Also, does putting a battering in parallel with the power supply filter the noise out? Are there cables running parallel to something that might induce a signal into the power cable. kd5und, Travis, mentioned that the problem does go away with a battery, but that he has not put the battery in the power circuit. It sound like it's either in the power supplies of the AC service to the shack.

kd0cdk, Don, suggested that the 2008/9 ARRL Handbook has a lot of information on noise problems and troubleshooting them. Also he suggested taking the house out of the power circuit with power going only to the shack to see if maybe there is something in the house wiring letting something in. If, during isolation, the problem goes away, you know it's something in the house. Also, have you tried installing a capacitor from the mic positive to ground? Also, are your computers on when you have this problem? kd5und, Travis, answered that he's turned the computers
off and the problem persists.

kd5njr, Scott, suggested that you can check the noise on the AC line with an oscilloscope by taking a few turns around the hot and connecting it to the 'scope probe. That ought to induce enough voltage to see what's going on without putting too much current into the 'scope.

n5kh, Will mentioned that Travis may want to keep an eye on the UPS charging system for his fork lift batteries as many of those UPSs are designed for a particular duty cycle, and the fork lift batteries might exceed that level.

kd5und, Travis, replied that he will start doing that and monitor the output voltage. He said he's been using that system for about 6 months with no problems yet and the system triggers it's alarms whenever he changes the load too greatly.

n5kh, Will, said that the idea to use the UPS charging system is a great idea.

End of Net

Continental Code vs. Morse Code

According to w2csl, Bob, what we now know and use as Morse Code was originally called "Continental Code". It was an upgrade from the first Morse Code that was developed in an effort to standardize code with other countries.

The picture shown above was found by David, my most recent AT&T U-verse installation tech. Dave responded to a call for help from me after I moved my computer back into our "office" from a recent remodeling fiasco.

We had AT&T out about two months ago to put in another Internet drop. The tech that responded then added a line to a temporary location in the house. He did not wire it into the system, but told Jim, our tile installer, how to wire it in when we're ready. So when we moved the computer from the office into our den, we just had to splice in the new wires. That tech told us that we could just leave it that way when we moved back to the newly tiled "office". When we did move (eventually) back into the office, we could not get the internet back up.

David showed up and found that the, now unused, temporary wiring still hooked to the system acted like an antenna and allow enough noise into the system that the signals would not sync in. Our 3-in-one package left us without TV, internet, and phones. All David had to do was disconnect the unused pairs and the system popped back up.

David noticed some of the HAM paraphernalia in the office and we talked a little about it. David mentioned that he had found a handwritten table of Morse Code vs. Continental Code inside a 1901 printing of Longfellow's Poems, brittle from age, which he bought at a garage sale.

David scanned the old document and e-mailed it to me. That is it pictured above.

A teeny bit of code history.



ke5omv
Don

Tech Net Notes October 30, 2009

We didn't get very far into the tech net before the repeater went Ka-bloooey. During a transmission the repeater timed out...and that seemed to have done something to disable it's operation.

Thanks to those who tuned in...or at least, tried to.

Sorry, we'll give it another shot:
November 11, 2009 - 146.910 - 7:00 PM
November 27th, 2009 - 147.045, 443.850 & linked system - 9:00 PM

Enjoy the weather!

Don
ke5omv

Tech Net Notes October 14, 2009

On this one we started off again without a topic.

w5ydl, Dan, changed all that with a question: He said that he's planning on putting up a 6 meter dipole and working 50.125. He asked "Is there anyone who can tell me a little bit about working 6M?

(NOTE: See kd5njr, Scott's comments on this by scrolling to the bottom of this post and clicking on "comments".)

kb5vdb, Ron, checked in and reminded us of Paul's upcoming deployment to Afganistan. In addition Ron passed on the recent new of a husband, wife, and son who died while installing a ham radio antenna. It fell into a 13,000 volt transmission line. Apparently they were not hams, but putting it up for a friend.

ke5yoo, Mike, mentioned that kd5njr, Scott's loop antenna was at about 50 feet. Orientation was the bigger question, with vertical giving you a possibly lower take-off angle. In addition Mike mentioned that ke5otq, Dennis is going to make some 2M loops.

kk5edd, Ed, said that he has been doing PSK31 on 20 meters lately and has plans on mounting an HF antenna onto his 5th wheel, if he can get a good idea of a good way to do that.

ke5yoo, Mike, mentioned that height-wise, one wavelength off the ground is good, but with 6 meters and greater, the higher you get the antenna, the better.

kd5cny, Tom, suggested to kk5edd, Ed that screwdriver antennas usually work well on motor homes and such. He also said that a long wire, hung from trees works better with a tuner. He mentioned that another option might be a vertical.

kk5edd, Ed asked, "Is the vertical you're speaking of, a multi-band?"

kd5cny, Tom answered, "If you have a tuner, the vertical should be able to take care of working multi-band." He added, regarding antenna height, "It's good to get the load of the antenna over the 1st wavelength." He said that between the 1st and 2nd wavelength, there's not much noticeable difference... abpve the 2nd wavelength, there's a lot of difference. He also mentioned that kd5cuz, Craig, has had a problem working his Garmen GPS with his 10 meter radio. He said that when Craig turns on his 10 Meter radio, the GPS quits working. It wont receive satellite data. Turn the 10M radio off, and the GPS starts working again. The radio does not have to be transmitting, just turned on. No problems when he fires up on 2M or 440mhz.

kb5vdb,Ron says that it sounds like the IF is interfering with the GPS and causing the
signals to the GPS to cancel out.

ae5ln, Paul, said that he (also) has been messing around with PSK31. "Where's a good place to pick up a signal?"

kk5edd, Ed answered, "14.070 on 20 meters".

ae5ln, Paul said that on 20 meters he locks up his computer.

kd5cny, Tom, suggested that Paul check the shields on his coax jumpers.


End of Net

Tech Net Notes September 25, 2009

ae5ft, Gene, suggested that "The 2 Meter Band Plan" be a topic for the Tech Net. So tonight this is what we put forth. The following information was taken from an ARRL Repeater Director with a little info mixed in that I found on the net:

Frequency Spacing
States East of the Mississippi - 20 kHz
States West of the Mississippi (excluding Texas) - 15/30 kHZ

Popular Simplex Frequencies Nationwide
146.49
146.505
146.520 National Calling Frequency
146.535
145.55
146.56 (in Texas)
146.58

Simplex
146.4 - 146.58
147.42 - 147.57

SSB
144.200 Calling Frequency
144.20 - 144.275


ke5cub, Lee, was the first to check in with a question. The question was, "What's the difference between resonance of the antenna and low SWR, and how to they affect each other?

We had a few check-ins but no takers until ad5pe, Jay, offered an explanation to Lee's question. I wish that I could repeat Jay's answer, but I did not have my recorder set up and my note-taking failed me. With that in mind I will try to encapsulate that which I can remember. I will do this with the help of:
http://www.radio-electronics.com/info/antennas/basics/resonance.php
http://qsl.net/g3yrc/antenna basics.htm


To start off with, resonance is a vastly overrated concept. But what is antenna resonance?

An RF antenna is a form of tuned circuit consisting of inductance and capacitance, and as a result it has a resonant frequency. This is the frequency where the capacitive and inductive reactances cancel each other out. At this point the RF antenna appears purely resistive.

The capacitance and inductance of an RF antenna are determined by its physical properties and the environment in which it is located. The larger the antenna or more strictly the antenna elements, the lower the resonant frequency.

The magnetic field that your antenna puts out will produce an electric current on any metal surface that it strikes, however if the metal that the signal strikes has a length relation to itself, the current will be much stronger on the object. If the object that the magnetic wave strikes is 1/2 wave length, 1/4 wavelength, or 1 full wavelength, then the induced current will be much higher than if the signal struck an object that was not some appreciable fraction of the wavelength of the signal. An antenna is "tuned" at for an exact wavelength. For that exact frequency that antenna is resonant. Every antenna has at least one exact resonance point.

Antenna resonance is the frequency, in MHz, where the antenna is in a state of electrical balance, which is determined by the length of the antenna.

SWR (Standing wave reflected) is the phenomenon that exists when power which initially was sent into the antenna is reflected back toward the radio. The SWR is measured in a ratio, for example 1.5:1 (or 1.5 to 1). How much power gets reflected back into the radio is dependent on the impedance of the radio/coax/antenna. If it's matched perfectly, the power reflected will be near zero (or said another way, an exact match, 1:1).

The impedance of the antenna is a function of the frequency being transmitted and the point at which the antenna is resonant.

Though your antenna may be resonant at a particular frequency, It is more important that the SWR not surpass levels that would be harmful to your radio. You can talk fine on an antenna that is not very resonant, but a high SWR can burn up the
"finals" in your radio.

ke5cub, Lee, added that "Resonant means that the antenna vibrates at it's assigned frequency. Keep the SWR below 2.1:1."

ae5jz, Tom, checked in and said that on his "waterfall" on PSK 31, there is a signal line less than 7 cycles wide at various places along the band, without modulation. He asked if anyone had any ideas about what that was.

k5bbm, Brian, asked, "At what frequencies do you transmit PSK31 on 2 meters?

kk5edd, Ed, suggested that it may be (according to his reference material) that 144.144 for vhf and 432.2 for uhf.

I don't recall who it was, but I believe someone suggested that the 7 cycle line on Tom's waterfall may be associated to some of Tom's equipment.

With that there were no more check-ins, and the Net ended.

Tech Net Notes September 9, 2009

There was no topic for the Tech Net this time. Instead... we had rain. Lots of rain. Even though Tulsa proper did not get buckets full, Northeast Oklahoma received steady rain for the day and somewhat previous.

w9nbc, Steve, came on during the intro to report street flooding on Memorial from 101st to 111th. Though the rain was settling down a bit, the water, the rain, and the lightning was on our minds.

w2csl, Bob, was the first to check and posed two questions:

1. Why are we called "Hams"?
2. How many Hams checking in tonight have been commercial operators, licensed by the FCC?

kb5vdb, Ron, came on to take a stab at the first question. He mentioned that he had heard that it may have had to do with Hiram Percy Maxim, who is considered to be the "father of Ham radio". Ron said that his initials, HPM , may have been the source from which HAM was derived, although there is no known evidence to say that is definitely the case.

w9nbc, Steve, checked in and said that he had been FCC First Class licensed with radar.

ad5jl, Bob, said he remembered something in QST being written about the "ham" moniker, but doesn't recall exactly what was said. Bob was also licensed through the FCC as First Class. In addition he posed the question, "How do you check to insure that the safety ground lug in a receptacle in your house is wired correctly, going back to a ground rod?

wb5uuw, Earl, checked in and mentioned that he was FCC Licensed First Class. Regarding checking for a ground he said that first you verify that you have a physical ground (rod) tied to the breaker box. He mentioned that the ground should be connected to the ground bus in the breaker box. If that is the case, go to the receptacle and check the AC+ against the Safety ground socket for 110 (120) VAC. If it check's OK, check the return (wide part of the socket) against the Safety ground socket for 100 (120) VAC. If no voltage, that's good. You can then check for continuity between the return (wide part of the socket). There should be continuity.
It is important to mention here that you follow that sequence. Check for your voltages before you check for continuity...and...(of course) do not check for continuity between the AC+ (narrow part of the socket) and the Safety ground.

NOTE: Understand? If you've got voltage between two points and you try to check for continuity, it may melt your meter into your carpet...and it's so hard to get melted plastic out of your carpet. Plus it may blow up your meter and send the indicator needle through your forehead and into orbit. Those indicator needles are hard enough to replace as it is!

ke5lnn, Dave, said that he has one of the line testers (plugs into a receptacle and analyzes voltages and grounds) and that it's served him well. Dave also made the point that the the piece of equipment that your connecting to a ground needs to be opened up to make sure that the chassis is wired to the ground of the AC power cable into the unit.

ke5otq, Dennis, added that there are ground fault detectors that can be purchased which will do the trick. Regarding the origin of "Ham" he suggested that it may have related back to one of the first guys licensed.

Linking Repeaters

Linking repeaters is done all over the country. When one repeater is linked to another, whoever keys up on one, can now be heard on both. This can extend the range of a radio.

And if several, well placed repeaters are linked together, the ability to communicate over the total area of all the involved repeaters can be a valuable asset to communications (especially emergency, public service, and disaster related communications). Most of us are familiar with TARCs UHF network which serves much of Eastern Oklahoma with repeaters in:

Tulsa 443.850
Manford 442.000
Tahlequah 442.225
Cavanal Mt. 442.250
Muskogee 443.100
Stillwater 444.525
Mounds 444.600 (having some problems at this time)
Ponca City 444.700 (having some problems at this time)
Bartlesville 444.975 (having some problems at this time)
McCalister 444.975
Edmond 443.250
Fayetteville, AR 444.925
Decater, AR 442.850
Ketchum 444.875 (temporarily out of service)
Daisy 444.400

Also I just found that there seems to be a linked system that covers much of Western Oklahoma. This was pulled from the internet at: http://www.srh.noaa.gov/oun/skywarn/.

"The NWS Norman SKYWARN Radio Network should be thought of as a "liaison net" during severe weather. It is not intended to collect individual spotter reports, but rather to serve as a collection point where local spotter networks can relay information to the NWS. In other words, the individual storm spotter should use their local frequencies and procedures to report severe weather to their local organization. When the local spotter net receives a report of severe weather, a liaison from that group relays the report to the National Weather Service via the liaison net. Amateur radio operators at the NWS Office will also provide radar information and the latest warnings and statements to the liaisons, who in turn pass the information on to their local spotter network.

Spotters and anyone else interested in keeping track of severe storms are encouraged to monitor these frequencies, but traffic should be limited on the liaison net. You should attempt to report severe weather to your local spotter groups instead of on these frequencies."

Much of the following is taken from http://repeater-builder.com/rbtip/repeaterlinking.html


There are other areas around the country that have linked systems as well. For example:

Alabama - 29 repeaters

Arizona - 22 repeaters

West Texas (Davis Mountain)

Cactus Intertie - icludes parts of California, Arizona, New Mexico, Nevada, Utah, Colorado, & Texas.

Colorado - 15 repeaters

South Carolina - 4 repeaters

Illinois/Indiana

Tennessee

Target Link - Parts of Pennsylvania, Maryland, Virginia, and West Virginia.


The "Remote Base" type link system is the most common because of its simplicity and low cost. Basically a second radio (even an old hand held or mobile rig) is connected to a repeater that you want linked to another. It uses that new radio as if it was a regular "user radio" on the other system. The "link" radio need not be duplex because of the way the link and repeaters are configured. Naturally the link (remote base) radio will need to be on the same band, frequency, split, and PL as the repeater you are linking to.


ae5ft, Gene, had the following information on IRLP as a mode for linking radio systems.

http://www.irlp.net/

The aim of this project is to reliably and inexpensively link amateur radio systems without the use of RF links, leased lines, or satellites.

The IRLP uses Voice-Over-IP (VoIP) custom software and hardware. Coupled with the power of the Internet, IRLP will link your repeater site or simplex station to the world in a simple and cost effective way.

IRLP operates a worldwide network of dedicated servers and nodes offering very stable worldwide voice communications between hundreds of towns and cities. All this with unsurpassed uptimes and the full dynamic range of telephone quality audio.

kd5cub, Lee, asked if anyone had any information on the FT-2000 100 watt with pep upgrade. If anyone has information on this equipment please contact kd5cub.

wa5vxi, Manuel, asked if other repeater systems use modes other than rf to connect up between repeaters (in particular, maybe using the internet).

ke5okt, Jim, mentioned that the newly running 430 repeater in Sapulpa was recently connected to another repeater (I believe in the OKC area) via Echolink (which is via the internet) but that it is not normally linked up. It can be done (and is likely being done in other places).

kd5guu, John, said that he regularly checks into an Echolink repeater on a Railroad Net on Tuesday evenings that is run out of Wisconsin. He mentioned that is a very operational and effective system.

ae5ft, Gene, added that our (TARC's) system is rf to rf, but IRLP is a very valid and easy to operate system for internet linking. He provided the IRLP info a few paragraphs up.

ke5zcz, Mike, announced that he is a scout leader and that the scouts are selling popcorn, as a fund-raiser, and that those who may run across a popcorn-selling scout, please consider buying some to help support this very worthwhile organization.

End of Net -

Tech Net Notes July 31, 2009

Here lately the Broken Arrow Amateur Radio Club has been doing some work on their 145.450 repeater located in the Bixby/Leonard area. In addition TARCs 443.850 repeater was just repaired today after a few weeks of low audio.

Also, in the recent past, RCWA's repeater got hit by a surge or a lightning strike and was off the air completely. As an interim solution, ww5wow Larry, used a repeater set up he had that would receive your signal and then re-transmit it on the same frequency. Your transmission would be stored in memory and then re-transmitted. You would hear, along with everyone else, what you just said. And this would all occur in simplex mode. The repeater would be listening and repeating on the same frequency. It made for slower transmission rates, but it did accomplish the goal of boosting a signal beyond it's limits (in most cases).

As an extension of that repeater work going on in the Tulsa area, we will be talking about repeaters here on the Tech Net tonight.

kb5vdb, Ron, sent in this explanation of repeaters:

A ham radio repeater is basically a radio system that receives the weak signal from mobile and portable radios, and re-transmits the signal on a different frequency at a much higher power level. Repeaters are usually mounted on TV and Radio broadcast towers, tall buildings, high hills, or mountains to extend the range of the station as far as possible.

The basic components of a repeater are the receiver, the transmitter, the controller, the power supply, the feed-line, the antenna or antennas (whichever applies), possibly a power amplifier, and a duplexer (cans) if one antenna is used.

There are two ways to construct a repeater:

1. Mount a single antenna as high as possible, and use it to both transmit and receive. Feed it with a single feed-line after running the signal through the duplexer. The big problem with this design is:

a. The cans are expensive, ornery, and delicate.
b. They have to be properly tuned, which requires a lot of EXPENSIVE equipment and a very knowledgeable technician.
c. They have a tendency to drift and become un-tuned.
d. They cause a lot of signal loss. (You also have to figure in feed-line loss for long runs.)

2. Mount separate transmit, and receive antennas as high as possible, separating the antennas by at least 100 feet. The big problem is expense of two antennas, two feed-lines, and of course, having to place the antennas at different levels on the antenna support. The big plus is no cans (and subsequently no loss through the cans) and if the repeater operator can locate the repeater box as close as possible to the antennas, you get most of your signal out.

There is a little delay every time that you key up, with some delays being substantial. Always allow a second or two before you start to talk.

The controller, by the way, allows a radio to become a repeater by allowing the transmitter and receiver to both operate at the same time.

ac5jm, Jerry, checked in and mentioned that there are a lot of variations to repeater set-ups but that Ron's explanation was a good summary. The on-frequency repeater, ww5wow's, is especially good for an emergency or disaster situation. It also might have an application on 10-meters since there is only 100 khz bandwidth, but nearly impossible to do without a dual site antenna. It's a good back up to have stashed away in case you need it.

The low audio problem on the 443.850 machine was a level problem. The site owner changed the temperature in the equipment room which allowed the pots to go out of tune.

ae5ft, Gene, asked. "Regarding the cans that have to be tuned: How does that fit in with repeater operation?"

k6jxy, Paul, answered, "The cavities keep the transmitter from getting into the receiver. They operate as a set. They are usually a six-pack on a set."

ke5okt, Jim, said, "I still have a KendeComm repeater that I'd like to get running on VHF. If anyone has any information on this brand or type of repeater, please e-mail me at jim@mounds.org.

ae5mn, Hank, asked, "Is there circuitry that separates the signal by detection of signal direction?"

ac5jm, Jerry, answered, "The receive side of the duplexer filters out the transmit and vice versa. The cans are manufactured for a specific range of frequencies and have to be tuned to be resonant to the frequencies used.

ke5zcz, Mike, asked. "Which repeater is better to have, one antenna/duplexer or two antennas, for a base repeater and what is the price range?"

kb5vdb, Ron, answered, "If you have a tower tall enough to separate the antenna by about 100 ft. and can get the radio close enough, you don't have the duplexers and the problems associated with them. If you don't have a taller tower, it's best to go with a duplexer. As far as costs... in the neighborhood of $5000.

ke5vas, Tim, asked, "Are there other linked repeater systems that cover as wide of an area as this one? How is the care and maintenance of the other repeaters handled?

kb5vdb, Ron, answered, "Maintenance is taken care of by the areas clubs, volunteers, and whatever funds they can raise. There was a linked system called Buffalo. It's not around anymore.

ac5jm, Jerry, added, "There are a lot of different clubs that have joined because of the affiliation with the National Weather System. The linked system is laid out to support the NWS. Ther are a few exceptions to this: Stillwater, Edmond, and Ponca City.

Tech Net Notes July 8, 2009

On the day of the Net we had a bit of unexpected rain. For most of us, rain, and especially lightning, affects our radio activity. To reduce my exposure to lightning, I usually will move my radio operation to a battery powered radio hooked to an attic antenna. The base radio gets unplugged from AC. I physically unplug my power supply from the wall. In addition, I unscrew the PL-259 connector from the back of the radio and let it dangle, not allowing the antenna connector to touch anything. I do not ground the plug.

My question, to those who check in tonight is: What do you do with your radio equipment during a storm?

Ron, kb5vdb, said that he didn't know if there is anything you can do to protect yourself from a lightning strike. Air is the best insulator that we know of, and lightning passes through air easily. He mentioned that he unplugs from the AC source and may hook to a magnet mount antenna. He mentioned that he had a friend that was hit by lightning while driving a tractor. The lightning hit him in the head and came out of his foot; he lived.

The story below was found at: http//www.dailycognition.com/index.php/2007/04/27/story-of-a-man-who-was-struck-by-lightning-7-times.html.

"US Park Ranger Roy C. Sullivan from Virginia holds the record for the person most struck by lightning - and living to tell the tale. Between 1942 and 1983, Roy has the dubious distinction of being struck by lightning seven times. He was known as the Human Lightning Rod.

The first lightning strike in 1942 happened as he was working in a lookout tower and the lightning bolt shot through his leg and knocked his big toenail off.

In 1969 while he was driving along a mountain road a second strike burned off his eyebrows and knocked him unconscious. Another strike just a year later, while he was walking across his yard to get his mail, left his shoulder seared.

He was standing in the office at the ranger station in 1972 when lightning set his hair on fire and Roy had to throw a bucket of water over his head to cool off. A year later, after his hair had grown back, a lightning bolt ripped through his hat and hit him on the the head, setting his hair on fire again. It threw him our of his truck, knocked his left shoe off and seared his legs. A sixth strike hit him in 1976 while he was checking on a campsite, injuring his ankle.

The last lightning bolt to hit Roy in 1977 happened while he was fishing. It sent him to the hospital with chest and stomach burns.

Roy Sullivan was never killed by lightning - he committed suicide while in his 70's in 1983 reportedly distraught over the loss of a woman."

Mike, ke5yoo, added that on a direct hit, there's not a lot that you can do. As long as you have a good solid single point ground at your antenna, then you shouldn't have a problem. As the voltage increases from a surge, the potential may rise in all of your equipment, but your equipment needs to be unplugged. If you get hit by lightning in another part of the house, and the lightning finds another path through your equipment, you'll have damage.

It stands to reason that your exposure to lightning, or subsequent power surges resulting from lightning, is related to the exposed inputs into your equipment. For most of us there are two avenues that allow this. The AC input to your equipment is one and the antenna input to your equipment is the other. If you have computer or other devices connected to your equipment, they may also provide an avenue.

The ARRL has a two-part article that addresses Lightning Protection. The first part is found at: http://www.arrl.org/tis/info/pdf/0206056.pdf . The second part can be found at: http://www.arrl.org/tis/info/pdf/0207048.pdf .

Tim, ke5vas, mentioned that American Power Conversions has a number of Uninterruptable Power Supplies that provide a level of protection against surges, particularly power drops. He said that he is at the end of a line and suffers a lot of power drops.

APS UPSs are available from office supply stores such as: Office Depot, Office Max, and Staples. They can also be found at electronics stores, like Best Buy.

More can be found on APS at: http://www.apc.com

Paul, ae5pb, suggested the use of Polyphaser as a source for protection. "Various amateur catalogs (AES for sure) stock some Polyphaser products. Electronics supply houses generally stock a more comprehensive inventory. You can find bunches of them on the internet. These are the industry standard - USACE uses tons of them in radio and also remote sensing applications. I'll bet I've written purchase orders for over a hundred of them. Their lightning protection handbook is the best out there.

Hoffman boxes are NEMA (National Electrical Manufacturers Association) spec enclosures. Though this is a specific brand, it's kind of like kleenex or band aid, and has come to mean any such box.

AES sells one that will hold Polyphaser copper single point ground panel, with in/outs for two coax lines. I'm going to use one with three coax ports, with the Polyphasers on the ground panel inside."

Polyphaser's website is located at: http://www.polyphaser.com .

Dave, ke5lnn, said that he has extensively used Polyphasers on his rig on every coax. He had the electric company put in a surge suppressor on the other side of the meter. During a storn he unplugs everything that has a wire in it. The idea is that the coax comes into a connector outside with a copper plate. He said that he's also heard that you can use a glass insulator, like a bottle to put your connector into inside. But that could create a glass bomb!

Note: I couldn't find anything on the internet that mentioned the use of glass insulators for isolating your PL-259 connector. If anyone knows anything about this, I'd be interested in hearing about it. I imagine that unless the glass is pure with virtually no air pockets, then the heat from a lightning strike could possibly cause the air in the pockets to expand, quickly, causing a "glass grenade", much like what Dave mentioned above.

Hank, ae5mn, mentioned that his exterior antenna gets disconnected during a storm and that in the future he intends to disconnect the power as well.

Ron, kb5vdb, added that most antennas are DC grounds anyway, but that Hank's, being a j-pole, will not be.

NTS - National Traffic System

In this post we will attempt to explain NTS, what it is and what it does. The information here was taken from: http://www.arrl.org/FandES/field/nts-mpg/ and loosely paraphrased. My deepest apologies!

What did I just hear?

Do you remember the game where you would pass a message around a group of folks standing in a circle? One person would whisper a message into the ear of the next person, who would then whisper the message into the ear of the next person, until it made it all around the circle and back to the originator. Oftentimes it was humorous and sometimes amazing to see how badly the message was maligned during it's trip around the room.

In that instance, the entire group of people was like a conduit and each person was an interface that had to re-transmit the message as if a link in this chain of communication. And, as said in the proverbial analogy, "the chain was only as good as it's weakest link". It was a fun game and well illustrated how perverted a message can get when relayed down numerous "links".

In an emergency situation communication becomes supremely important and is often viewed with solemnity and reverence. When lives hang in the balance, the time for frivolity has passed, and the time for focus and sobriety is at hand. To be a link in the chain of emergency communications becomes a serious matter. If you have the opportunity to be a link in that chain, at that time, you will likely want to be a strong link.

This is much of what NTS does. It organizes, trains, prepares, and tests the links of communications. When the time comes, you just revert to your training, instead of trying to re-invent the wheel. If done correctly the information you pass along may make a difference in someone's life.

The ARRL manages and operates the National Traffic System to assure a continuing and reliable structure to handle formal message traffic in the US. Though it may not be as "lay-back" as a comfortable ragchew on an informal net, there is great value to be had knowing that you can pass traffic effectively and efficiently. When time is of the essence, there may be no valuable substitute for effectiveness and efficiency.

We, as amateur radio operators, have many resources at our disposal for communicating. Not only to we have a number of bands available, but we also have a variety of modes available, such as voice, CW, SSB, and digital, and we have a multitude of delivery systems, horizontal, vertical, NVIS, or reflected off satellites. When an emergency occurs, we often have the means to relay vital information.

"The Fingerbone's connected to the Wristbone, and the Wristbone's connected to the Armbone"

So how do we all connect to each other in order to facilitate effective and efficient emergency communication? It all starts at the local level with ARES. The Amateur Radio Emergency Service. When you affiliate with ARES, you become a link in this recognized chain of communication.

Local ARES Nets link to
District Nets who link to
Section Nets and Traffic Managers who link to
Region Net Managers who link to
Area Net Managers who link to
NTS who links to
ARRL HQ

Of course, it may be a bit more complicated than that, but that is a general idea of how it works.

Tech Net Notes May 29, 2009

On this evening's net the topic was NVIS. After a brief description of Near-Vertical Incident Skywave (much like the post below this one), we opened the net for check-ins.

ke5okt, Jim, checked in with a question. He has a KendeCom, model KRP-5000 repeater and can't find much information on it. He asked if anyone has information on this brand, such as how to find parts and documentation. kb5vdb, Ron, mentioned that aa5v, Steve, may have a repeater of that brand in his garage, and may know something more about them. Steve is a member of TRO and may be contacted through the club. If anyone has information they think Jim might be able to use about the KendeCom repeaters, he can be contacted at jim@mounds.org.

n5tda, Rex, mentioned that he has a G5RV up at about 25 ft., which would be less than 1/4 wavelength and would fall into the NVIS category. He mentioned that he was not able to get within the 500 mile skip zone at that height.

ke5lnn, Dave, asked if NVIS is in wide use by any particular amateur radio groups. In addition, Dave has a TE Systems 1412G, 2 meter amplifier. He says it works fine on two meter but doesn't work on 70cm. He has heard of a mod that can be done to allow it to work on 70 cm and wants to know if anyone knows how to install that mod. w5ydl, Dan, says he also has one of those amplifiers and that he too would like it to work on 70 cm, but doesn't know how to install the mod. Dave mentioned that he may be able to reach someone at TE tech support who can help.

ka0oxn, Rich, said that he had a 160M installed at about .o4 wavelength height that was good out to about 400 miles. He also had a 40M installed at 10 ft. that was good to about 300 miles.

na5dw, Dan, said that he would like to find a way to get his HF signal from Fairplay, CO to Denver, CO, about 90 miles. He tried a dipole hooked up to his truck's tailgate, on one end, and to a signpost on the other end, about 3 ft. high, 20M or 40M, and couldn't quite make the trip.

ae5ft, Gene, said that n5fem, Steve, was talking into the Dallas, Texas area on 40M, on the NVIS dipole mounted at 5 ft. at the last Route 66 event in Chandler Park. He also mentioned that he uses an NVIS antenna every day to check into the Oklahoma Sooner Traffic Net, which is a part of the National Traffic system Net. His antenna, he calls an "extreme" NVIS antenna, which is a G5RV mounted along the top of his wooden fence at about 6 ft, with about 10 ft. of wrap on each end, fed with about 30ft. of twin-lead and a short piece of coax. He says that he is about 90% effective getting into the net on 80M. He says he's worked both coasts during the Route 66 Contest where folks were trying to make contact with him as a Route 66 station. So it may not be all that good of a test, coast to coast.

ae5mn, Hank, mentioned that this might be an HF solution to his problem of finding something that would fit in with his neighborhood covenants.

kk5edd, Ed, said that he's in the process of building an NVIS antenna, from plans of Dr. Carl Gellenik, n6vng, with two 38ft. elements and then at 90 degrees from them, two 25 ft. elements. The design calls for a threaded center conductor on a SO-239 plug, which Ed is having trouble finding/fabricating. Ed would appreciate hearing back from anyone who might have information on how to find a threaded SO-239 center connector such as this.

ae5ft, Gene, mentioned also that in NVIS applications, we have to look at the maximum usable frequency. That is the maximum frequency that will bounce of (versus penetrating) the ionosphere. That "maximum frequency" can depend a lot on conditions, sunspot activity, and etc. Gene mentioned that 40 M is "iffy" on NVIS, which may explain na5dw's, problem making a 90 mile trip in Colorado. The other thing Gene mentioned, is that when you're looking at 80M NVIS, that's what most dipole installations are, to at least some degree. Few of us can afford to construct 120 ft towers for your dipole!

ke5und, Travis, checked in and mentioned that he's used NVIS technology inadvertently. He understands the principle but now knows what to call it. Travis asked if NVIS relates more to angle of take off. ae5ft, Gene, answered that yes, angle of take off is one of the parameters that NVIS defines. Travis mentioned also that this is probably why he can make it in to Albuquerque, NM but can't quite make the trip into Arizona.

NVIS (Near-Vertical Incident Skywave)

What is NVIS?

Near-Vertical (meaning somewhere around straight up) Incident (an event, something that happens) Skywave (the reflecting of a signal, usually RF, off the ionosphere). Think of it as pointing your antenna straight up and having the signal "shower" down all around you.

NVIS - compared to what?

Think of the two modes of antenna orientation with which we are most familiar: vertical and horizontal.

Vertical - line of sight, groundwave propagation

Horizontal - long-distance, skip

'Splain yourself!

If you can talk about 50 miles on a vertical antenna predictably, and on the horizontal plane you can pretty much count on shooting over most stations that are closer than 500 miles away, NVIS is a method that you can use to fill the gap (skip zone). NVIS allows you to have more reliable communications with stations within a 100-200 mile range.

Great! How do I do it?

You do this by directing your signal straight up. Rather than pointing your beam directly overhead, you can do it the easy way. Cut a dipole to the desired frequency, and install it less than 1/4 wave above ground. Last September at the Route 66 event in Chandler Park, N5FEM, Steve, installed one at about 5 feet and did very well with it. By installing it closer to the ground, you are using the ground as a reflector. In a sense, it becomes an upward pointed beam.


Putting One On Top of a Hill

Well...yes you can...but...with valleys generally containing more moisture than hilltops, often-times you get a better reflection in a valley. And, after all, you're directing your signal upward, so a valley may be more advantageous, especially if you're trying to avoid detection (military applications).


What Bands?

Generally speaking, 160M, 80/75M, 60M, & 40M is where you can use this system most effectively. As we have learned, the higher frequencies will tend to penetrate the ionosphere more, and reflect off the ionosphere less.


Why bother?

In an emergency or if you have friends within the dreaded skip zone (200 miles), this allows us to have fairly predictable communications. Skipping on the horizontal plane is not that predictable, and where it is predictable, may not be that useful. On the vertical plane, line-of-sight may not cut it. You often need more. NVIS fills the gap between the two.

You can read more about this at: athensarc.org/nvis.asp