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New portable antenna for Field Day

I spent a good chunk of this weekend putzing around working on this project. I had to run to the metro for aluminum, I had to setup the new vertical mill to use the aluminum, I needed a small project box for the balun, etc. 

I started out with fabricating a new base. It has 6 conduit hangers on the bottom, an insulated 3/8" mount, and some bolts with wing nuts for the radials.

Top side of the base.

Bottom of the base showing the conduit hangers and the insulated 3/8" mount

The base and conduit (support) deployed in the driveway for testing

Closeup showing the base+radials+loading coil+bottom of the mast

I am currently using a Wolf Creek Coil (I plan to make my own once my lathe shows up later this summer) so I pulled out the antenna analyzer to document the tap point for each of the bands.

The whole system is pretty small as the longest pieces are five feet long and they could be shortened a bit if needed. The whole system takes about 10 minutes to setup and provides coverage 80m-->10m.

I am pretty happy with the overall design. This is much nicer than the prior version that I had been playing with this week and meets some additional requirements that I came up with as I thought through my various use cases. The family and I will be camping in south-eastern Minnesota later this week so I intend to try out the new antenna from the campsite prior to taking it to Montana for Field Day weekend.

My main antenna for Field Day will be a linked dipole (designed for 17m, 20m, 30m, 40m) for the high bands. This vertical will primarily be used for 80m and potentially 40m. I will also have a random wire antenna with as my backup.

I could see brining this antenna on future trips because it is small, covers all of the bands that I plan to operate, and is extremely quick+easy to setup, and does not require some sort of sky hook.

73 de NG0R

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HF antenna for the truck

I swapped out antennas for the truck for this weekends camping trip.

I have several sets of MFJ type Hamstick antennas for the truck but frankly storing and changing them is bit of pain. I decided to try something similar to what I am using the car these days.

Wolf River Coil for 10-80m setup for 17m (The untapped coil has about 83uH of inductance)

I tried several different configurations

  1. Coil + 102" whip (base loaded) 12m-->80m
  2. Coil + 20" mast + 48" whip (base loaded) 15m-->75m
  3. Coil + 48" whip (base loaded) 10m-->60m
  4. 20" mast + coil + 48" whip (center loaded) 10m-->60m

Ultimately I am going to use option #4 for this weekend.  I did not like that load of the 102" whip moving around in the wind as it has quite a bit of mass compared to the other options.

At 10m I am only using a couple of turns of inductance (top = 117) since it is almost a 1/4 wave tall

At 10m I am only using a couple of turns of inductance (top = 117) since it is almost a 1/4 wave tall

The configuration for the truck seemed quite a bit more complex to setup compared to with my car. The radio in the truck did not agree with the analyzer nearly as well as my experience doing this with my car. It took about 2.5 hours to setup the various configurations and then measure the results for each band.

This combination should work fine and I can quickly dissemble and store the components in the rear of my truck when they are not needed. With the tuning notes it should be pretty easy to change bands with a minimum amount of hassle.

73 de NG0R

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HF antenna for the clown car

I spent last week on the road traveling to FDIM 2014 (Four Days in May) and the Dayton Hamvention. As part of the road trip I operated quite a bit of HF from my small commuter car, a 2006 Ford Focus (84,000 miles so far.) 

HF as configured to the Dayton road trip - center loaded short vertical

I have a short center loaded vertical using a six meter MFJ style Ham Stick (which has no native loading coil) which is then split in half and I have a Wolf River 10-40m coil in the center of it. 

It tunes up fine 10m --> 20m with the center loaded configuration and gets out on 17m which is my primary day time mobile band. The problem is that it will not tune up on 40m which would be nice for evening QSOs.  Wolf River recommends base loading but I want to try to center loading since it is more efficient but requires more inductance. At the conclusion of the road trip I decided that I wanted more band options so I went back to base loading.

The clown car with the reconfigured antenna now set for base loading

Close up of the coil setup for 40m operation

Coil positions for the based loaded configuration

Tonight I ran outside with my antenna analyzer for 20 minutes and documented the configuration for when it is setup with base loading. I am getting pretty decent 10-->40m coverage. It is almost a little to tall for 10m but it squeaks in.

This is pretty sweat because when I want to change bands I simply push the ring to the bottom and count clicks as I move it upward to the proper position for the band of choice. I can also slight turn/twist the tap point on the coil to tweak up/down the inductance. The MFJ Ham stick splits into two sections for storage. All of the coil and antenna sections have quick disconnect fittings so every breaks down very quickly.

I need to setup my pickup with a similar configuration sometime soon.

73 de NG0R

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A trip to Dayton (FDIM+Hamvention)

It has been 11-12 years since the last time that I have traveled to Dayton for this big ham radio  weekend.

It has been a fun trip so far. I have really enjoyed all of the people that I have met and the opportunity to look at a lot of different designs and ideas as I think about some future projects.

73 de NG0R

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Gun Safety Class is complete

WooHoo... it is done.

A bunch of squirrelly kids trying to make it through a two hours class

Joe and his instructor getting setup on range day

A nice pattern on range day

Joe passed his written test with a 94% so we were all pretty happy with that.