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