On Saturday, WA4SKA had an antenna party and we installed a Dual Band Workman 2 meter 440 MHz up 20 feet on a push up pole. The food was great (she never cooked like that for me, LOL)!

Rick KG4MRH, Tracy (KG4MRG) and Chris (K8QV) took photos.

Da Food

Rick working on assembly

Rick is probably thinking, 'Nice legs!' (inside joke)

The mount

73,

Mike, N4MAA

Thanks to Bob Payne KI4QJG the tower mounted on the trailer will be done by field day. A few of you met Bob and his wife at Biff Burger at one of our meetings. Bob volunteered his services so we took him up on it. I will owe him dinner for a long time.

So when your meet Bob give him a big hand or hug for getting the tower on the trailer. It will have a 10, 15, & 20 Meter beam ready to get those contacts.

73,

Mike N4MAA

Check it out… It happens all the time! This was my latest mobile antenna problem. It has been a very good antenna and has been on the truck for over two years in the salt air of Saint Petersburg, Florida. I put the new spare on right after I replaced the coax with good stuff. If you make a good antenna why not go the extra little bit and put decent coax on the thing??? I will rebuild the old one with new coax and a paint job… maybe safety orange. Or maybe not!

Water can sure get into your antenna.

High SWR? No wonder… check yours today!

Mike N4MAA

I have no idea what the radiation pattern looked like but it tuned these bands with the built in tuner in my Yaesu FT-990 and Texas gave me a 5-7 from our QTH in Florida. Propagation was to the west and we received good signal reports from all stations we talked with. We were running 100 watts on battery power from a field on the Gulf of Mexico. Next we will make another vertical and a harness to try phased verticals.

I cut the vertical to 32 feet 6 inches and the radials at 32 feet 9 1/16 inches.

The first 1 foot is a fiberglass insert to insulate the aluminum sections vertical from the ground. The ring is an aluminum ring is 1/8 inch thick fashioned on my drill press and a copper sheet hammered over it for the radials to mount to.

I may make a loading coil and try for 80 meters. Another idea is a capacitance hat to see what happens. I’ll let you know in a while…

I drilled a hole where each section mates and color coded them so the holes would match with a 1/2 inch thick plastic support ring for the guy ropes. I have a measuring rope (a military way of doing things for the simple minded like me) of 23 feet hooked at the base of the vertical… I then go to three points on the compass to sink my support stakes. We tied off two guys with the pre-measured guy lines and walked the vertical up with Jim walking the antenna up (you need two people but Jim did it alone) and myself pulling the third guy line and clipping it on the third stake in the ground. Notice the 2 meter beam in the right hand corner of the picture so we could stay in touch with friends on our repeater.

Jim N4AAC and Tracy KG4MRG at the operating position it was a beautiful day in Florida. This was done close to Fort DeSoto Park in the southern part of Pinellas County, Florida.

By Jim KB1MVX

I recently installed a new transceiver in my truck. On the first day of using the new radio I got reports that I was transmitting very noticeable alternator whine. I could also hear it on receive and when the radio was quiet. I checked the diodes in the alternator, verified I had good grounds, and I even ran the truck with the alternator removed to be sure that the whine was indeed from the alternator.

The alternator produces AC, which is rectified into DC. The problem is the rectification is not perfect. The DC output will have a small AC signal riding on it. That AC signal will have 9 cycles for each revolution of the alternator. Suppose your engine is idling at 600 RPM and the drive pulley ratio to your alternator is 1:3. At that engine speed your alternator is turning 1800 RPM, which is 30 rotations per second. Each rotation gives you 9 cycles of AC. Do the math and you get a 270 Hz sinusoid (not a perfect sinusoid but close enough). Cruise down the road at 2000 RPM and you get a 900 Hz sinusoid riding on your DC power supply.

I tried an off the shelf filter from Advance Auto. It did very little so I decided to build a filter. The first filter I built worked VERY well. The problem is that not everyone has the tools required to build that filter so I decided to figure out a filter design that could be built in less than an hour by anyone with basic tools, have a cost under $20, and handle a current of at least 20 Amps.

Parts List:
1/2″ Quick Link (Lowe’s) $2.98
6x3x2″ project box (Radio Shack) $3.79
20′ roll 12 gauge red hook up wire (Radio Shack) $4.99
4700 uF 35V capacitor (Radio Shack) $5.29
18″ of black 16 gauge wire
Electrical tape
GOOP or similar glue
3 zip ties
Total: $17.05

Directions below:

1/2″ Quick Link will be used as the inductor core. A fellow ham, Dave KC1LT, suggested using a shackle. I went to get a shackle and came across this quick link. I went with the quick link to make more efficient use of project box space.

Beginning the winding
Wrap the hook up wire around the closed side of the quick link starting from the left as shown. Leave about 9″ of wire free on the left end. Try to keep the winds as close together and tight as possible. On the last layer space the winds so that you have 9″ of wire left on the right end. Use all 20′ of wire.

Above is the finished wrap

Wrap the coils in electrical tape and close the quick link. About 1.5″ from the right end of the inductor strip 1/4″ of insulation off the red wire and solder in the + lead of the capacitor. Make sure you observe the capacitor polarity. In the picture you can see the negative arrow on the capacitor pointing down. Solder the 18″ piece of black wire to the negative lead of the capacitor. (Above)

Cover the solder connections and capacitor leads with electrical tape. Drill a 3/16″ hole in both ends of the project box for the red wires. Drill an 1/8″ hole in one end of the project box for the black wire. Run the wires through the holes. Put a zip tie on each of the three wires to limit how far the wires can be pulled out of the box. Make sure to leave a little slack in the wires inside the box. Using GOOP or some other thick strong adhesive, glue the capacitor and inductor into the project box. Leave the cover off until the glue dries.

+12V Side with the capacitor to radio
Black Ground +12V to battery

Measured Filter Response:

I made this measurement using a low frequency signal generator and an oscilloscope. At 25 Hz the filter has better than 30 dB of attenuation. In other words for frequencies above 25 Hz the noise power has been knocked down by more than a factor of 1000. I am new to practical electronics. By answering basic questions and making suggestions several folks contributed to this. In particular Dave KC1LT was very helpful. I hope this information is useful. If you use this design to build a filter or if the information presented was useful please email me and let me know it was worth the effort to put this together.

73,

Jim
KB1MVX