VHF Contest Rover — New Antenna Setup

I’ve now officially entered Phase III of my VHF contest rover setup. Phase I involved running Diamond Yagi’s for 2m and 70cm on a painter pole. Phase II replaced the painter pole with a fiberglass push-up mast and added a Directive Systems 2m rover yagi and a Par Electronics stressed moxon for 6m. Now, Phase III mounts all that on the roof of my SUV along with a rotator and for good measure updates 70cm to a Directive Systems rover yagi.

My overall goal is to greatly ease my set up burden at each grid square. In the 2018 ARRL September VHF contest, I was really beat by the time I got to grid stop #7 late on Sunday. Plus, it was taking at least 30 minutes at each location to set things up.

The downside of this set up is that the maximum height of my mast is 12 feet versus the 20+ feet of the push-up mast. Even so, I’m hopeful that I’ll be able to add not only to my operating time but also to the number of grids I can activate, given the reduced set up time.

Rotator Mount

The rotator mount has been in the building process for a few months. The first aspect was constructing the base that is attached to the roof rack. It consists of 2×4 rails and cross members along  with a plywood deck. You can find a rough drawing here: Rotator Roof Mount

The rotator cage uses Steel-Tek pipes and flanges to essentially mimic a three-legged tower structure. On top of that is a DX Engineering DXE-AS455G tower shelf and their DXE-TB-300 thrust bearing. The mast is a six-foot fence post from Lowe’s hardware.

It then uses straps to attach the whole thing to the roof rack. I’ve tested it up to 75 to 80 mph with antennas. Of course, wind gusts from trucks going by will increase that force. All-in-all, it’s pretty sturdy. For example, I can grab the structure and haul myself up on the deck to work on the antennas.

Unfortunately, I also inadvertently tested it’s ability to withstand impact with tree branches. The mast structure was fine but the moxon on the top was ripped apart. I now realize that I need to put a note on the windshield to remind me of clearance distances, etc. This test happened because I was coming home and went my normal way, which has several low hanging trees over the street.

Antennas

For 6 meters, I’m using the Par Electronics SM-50 Stressed Moxon. It’s mounted at the top and extends over the each side of the car by a few inches. I may need to turn it sideways when traveling. I need to give that more thought. I didn’t feel that a 6m yagi would work as the elements would stretch still further past the sides of the car.

For 2 meters, I’m using Directive Systems DSE144-6RS six-element yagi. It’s 8 foot boom is just right for this set up. I added this antenna to the rover for the 2018 CQ WW VHF Contest. Sound construction and I like that the elements can be bent back into shape after contact. That’s what happened to me in the ARRL September contest in my last grid as the mast fell as I was trying to push it up during set up. That was my last grid and was I ever tired.

Directive Systems 432 RS Yagi

For 70 centimeters, I’ve added Directive Systems DSEFO432-15RS yagi. It, too, has an eight foot boom along with 15 elements. I will note that I purchased the kit version instead of the assembled version. In retrospect, I recommend paying just a bit more for the assembled version. The kit went together fine, but I discovered that one of the element holes was missing. Shipping that section of the boom back to Terry Price for drilling went quickly and got me back on track. But buying the assembled version would have avoided all the hassle.

Terry also provided me with updated quick mounts for both the Directive Systems yagis. He drilled a hole through the both boom and mast mounts then tapped the hole in the mast mount. This allows you to secure the boom and mast mounts using a bolt through both plates. That’s just what I needed to first easily mount the antennas at home and then secure them to the mast while driving on the road.

Next Steps

Next is cabling, setting up the operating table, and fitting all the equipment into place. I still plan to only operate while stationary. So the operating position will be in the back seat. When I get the station set up inside, I’ll write another blog post.

Of course, there are a few other improvements, most of which will present themselves during the contest. One that I’ve already been investigating is adding 220 MHz. But not sure that’s worth it with transverter, amp, and setting something up with the IC-9100 to drive it all. But, even so, it remains something to keep in mind.

Hope to work you in the ARRL January VHF Contest.