SKCC 5123T----- FISTS 14979----- Flying Pigs 2331----- NAQCC 3610-----QRP ARCI 14176-----Polar Bear 257

Sunday, May 29, 2011

Shortened Dipole with Matching Section

I tried a shortened dipole (inverted V) by using the IMAXMIN.EXE program on the W5DXP no tuner page. The minimum dipole length the program will accept is 107.19 feet for 3.5 MHz. So I went with 108 feet. The Imax or good length of open  wire feeder is 29.7 feet for velocity factor of .9. My chosen feed-line is 300 ohm window line from DX engineering. Note I am using a bead type choke balun at the end of the 300 ohm feed-line and converting to coax.

I tried this out with a portable mast consisting of 4 foot military mast sections. The bottom is a tripod using a tripod adapter I found on EBay. There is a six foot section of PVC conduit at the top. This gives the antenna a support at the center of 23 feet. The ends are going to stakes or a low fence. The ends are only about 3 feet off the ground. The SWR was very good at 3.5 MHz. A pleasant surprise is that 7 MHz the SWR is under 3 to 1. A full size 80 meter dipole will have a very high impedance on 40 meters. But this dipole is usable on 40 meters with a the internal tuner of my IC-703. I had done a similar check out for a 7 Mhz dipole at 54 feet of length and it tuned under 3 to 1 on 20 meters with a 14 foot 8 inch feed-line.

Now back to the 108 foot dipole. I got it to work on 20 meters by reducing the feed-line to about 24 feet. To try out different feed-line lengths I have a lot of 300 ohm sections of different lengths. I am using the European terminal strips ( the larger size) to join the sections and this works well. So you might say the the 108 foot dipole is like the G5RV and I would say you are right. I don't have one but it likely works the same. The 54 foot dipole is close to a G5RV Junior.

Now I am looking to use either the 108 or the 54 foot version at Field Day based on space available. I am not convinced the guys on the mast are needed with the tripod. They may backfire if a car catches one and turns the whole rig over. I have some homemade A-frame masts from a prior Field Day that I could use to get the ends of the dipoles up at 13 feet.

So credit goes to Cecil W5DXP for this no tuner concept and for me it explains what is going on for the G5RV type antennas.

Saturday, May 28, 2011

QRP session with WD0HDR

I met my friend Thomas at a park area in his sub-division Saturday morning. Thomas, WD0HDR, is a long time friend of the Lane family and recently moved back to Dothan after many years from Nebraska. Fortunately QRP is a our common interest and you may work him on 40 meters. We got on 40 and 20 meters with IC-703 and the Buddistick which was supported by a mast with a tripod at the base. The mast is made up of 4 foot military mast sections and the tripod adapter is a new find off of EBay.

Greg N4KGL

Saturday, May 14, 2011

Inverted V Checkout for Parking Lot Portable PLP

It turned out after the morning rain cleared, I setup at George Park in Panama City. One goal was to test various inverted Vs with the 20 foot mast on the back of the truck as the center support. The two legs of the inverted v dipole were the Coleman Laundry line spools with 85 foot of wire in each. So I wanted to get the length for several bands. The lengths worked out to be

40 meters: 30' 9"/31' 9" some how I got the two legs a foot different.
30 Meters 21 9" each leg
20 meters 15' 5" each leg
80 meter 62' 6" each leg

So as I went along I was making contacts including

40 meters with Sierra at 2 watts
     K3AP Bob Ocala, FL
    WR4Z Jimmy Panama City, FL (I had sent Jimmy an email and he found me)
     K3RLL Bob Cassadaga, FL ( He was QRP in a park like me)

30 Meters Sierra at 3 watts
     W5TZC Larry Bismarck AR

20 Meters SST at 3 watts (It was the FISTS Sprint)
     W3OKC Steve PA
     KG2GL Tony NJ
     KA8HFN Larry OH
     W2ED Ed NJ
     AK5D Dave NM
     W7GVE Ed AZ

On 80 meters I just verified the inverted v tuned. I am really pleased with the Coleman laundry spools for wire. It does not cause any problems to have the extra wire spooled. So now I have more configurations for Parking Lot Portable ops where the space is available for the ends of the inverted V.

Greg N4KGL

Wednesday, May 11, 2011

My Michigan Mighty Mite

A very simple transmitter. The circuit is at this link. Mine is for 40 meters. I setup the components each with their own terminal strip. There is Velcro on the bottom. The components can be placed on the board covered with matching Velcro. The idea was that I could disassemble and have the Grand Kids reassemble. Well maybe.

I got lucky and worked KE4WKH Orange Beach, AL. So that was about 115 miles. My power meter showing 1 watt out and my batteries are at 13.9 volts. That is a bit more than most get but I have 11 AAs in my battery pack. You will also notice the antenna switch that has the antenna as the common and switches to the receiver or the MMM. It is nice that on transmit the signal can be heard in the receiver as that is good for spotting and sidetone.

It is challenging to make contacts being rock bound. I just have to be patient and persistent. This takes me back to the Novice days! The MMM is being picked up by CW skimmers on the Reverse Beacon Network as far as Maryland..

W3EDP Antenna Checkout for PLP

I tried it and I like it. The W3EDP is a 85 foot long wire and a 17 foot counterpoise. The LDG 817 tuner lets me match it for 40 through 10 meters. I used LDG 1 to 1 balun directly on the tuner output for all but 15 meters and then switched to the LDG 4 to 1 to get 15 meters to tune. So this is just another possible configuration for Parking Lot Portable (PLP) ops.