St. Louis Vertical Part 3, Conclusion

This is part three, the conclusion of the construction of the St. Louis vertical.

I terminated each end of the twin lead by melting a small hole in between each conductor, large enough to fit a zip tie through and pulled in nice and tight. Then I stripped off insulation from each conductor and soldered them together – did this at each end of the twin lead coil. The bottom shorted conductor is kept bare and I use a good quality alligator clip to attach my coax center conductor. The orange wire is attached to a 17 1/2 foot counterpoise as seen below.

Here you can see the bright orange stake that I use in the field, along with the bright orange counterpoise so nobody trips over any of this stuff while operating portable.

Using alligator clips allows the use of multiple sized counterpoises to increase the efficiency of the St. Louis vertical while in use.

I carry a second stake with a 40 foot counterpoise. In this configuration the antenna resonates around 6.5Mhz. In a future version of this antenna I’ll add fewer turns of twin lead so it resonates close to 20 meters. I use an LDG tuner, the QRP Z11 along with my FT-817 and the tuner handles this antenna quite nicely.

The photo above shows the upper terminated connection with a male/female connector to attach the radiating element that extends to the tip of the Wonderpole. It provides an easy disconnect point for the radiating element.

 

These male/female connectors are available at most hardware stores that carry electrical supplies. I use heat shrink tubing to give all the connections a professional look and I think it extends the life of the antenna components. It doesn’t take long to add that extra finishing touch.

 

 

 

 

The antenna is staked on a ground spike used for beach umbrellas. It is a discontinued item that was available at Lee Valley Tools here in Ottawa. I attach a one inch wooden dowel about 3 – 4 feet long and to that I attach the St. Louis Vertical with large plastic zip ties. At the end of my session I just snip the zip ties off. The zip ties get the Wonderpole nice and snug against the non-reactive wooden dowel and if need be I can hammer some of the extra length of the wooden dowel into the ground for greater stability during windy conditions. I sharpened the end of the dowel for ease of insertion.

 

 

 

Here’s the St. Louis Vertical fully extended at the edge of my patio. This antenna is a great portable addition to operating in the field and it sets up in less than five minutes. My first contact was on 15 meters using 2 watts on PSK31 to a station in Slovenia with a 599 signal report.

Please let me know if you have any questions of the construction details.

St. Louis Vertical Part 1 - Prep

The St. Louis Vertical portable antenna has been talked about and modified over the years. It’s a very portable antenna solution for Field Day or QRP enthusiasts. It’s easy to build and modify and covers 40 meters to 10 meters with the use of a tuner. Radials are a must with this type of antenna. I use a Shakespeare Wonderpole, a collapsible fishing pole. Fully extended it’s 20 feet long and collapses to 45 inches for storage and transport.

Years ago I purchased a good amount of Radio Shack twin lead for this project and like any good ham I’m finally getting around to building a St. Louis vertical for use at Field Day and with the Ottawa Valley QRP Society group outings.

The first preparation that must be done on the Wonderpole is the removal of the two clips midway up on the first section. These two brass clips are used to hold a fishing reel. The reason for removing these two clips is to assure that the twinlead once wound on the lower section is flat against the bottom section when you wind it on. It’s more esthetics and it makes it easier to wind without the bumps of the clips underneath the twinlead.

I used a Dremel tool with a cutting disk attached to cut through the clips. I still have to smooth down the plastic adhesive used to attach the clips with a small grinding tool attachment on the Dremel.

For the last while I’ve been thinking quite hard to determine a good way to wind the twinlead onto the bottom section so it stays in place. In part 2 of this series I’ll show you a novel method that I devised to accomplish this – it’s weatherproof too.

Have been listening to 17m psk this afternoon and just finished working A71EM in Qatar with 40 watts on the R6000 vertical. 17 is a fine band with some great DX and quiet band conditions – opportune for working DX. It seems to be open early morning till sundown here near Ottawa – always with some exotic stations waiting to be worked.

Here’s a link from the American QRP Club describing the St. Louis Vertical:

AMQRP.ORG St. Louis Vertical