Friday, January 26, 2018

Mobile HF set-up

Lido cup holder mount, FT-891 head, and external speaker

A nice afternoon with no outstanding honey-do's allowed me time to finally install the FT-891 into my truck.

10-40m with a 102" whip
One reason for the procrastination had to do with trying to find a suitable location for the rig. Even with the main bulk of the radio installed under the seat, there is little room in most modern vehicles to install the remote head.

The other was the antenna. I wanted a multiband antenna but didn't want a High Sierra or other "screwdriver" type. That left individual Ham Sticks for the bands of interest - a solution that quickly gets expensive and results in too  much clutter to carry along.

I recently found out about the Wolf River Coil (the Silver Bullet Mini in my case) and it seems to be exactly what I was looking for. It provides 10-40-meter operation with a standard 102" CB whip with taps on the coil providing the proper loading for the band of interest.

What I like about it:
  • the whip can be bought (cheaply) anywhere CB's are sold
  • it is unobtrusive compared to other multi-band antennas
  • the whip's 102" length is more efficient than other antennas and will have a broader bandwidth
  • reviews are consistently high

Here is an interior photo showing how the tap contacts the coil. Sliding the collar up
or down the coil allows it to achieve resonance anywhere from 7 to 30 MHz when using a 102" CB whip antenna.

This is effectively a manual version of the screwdriver antennas, therefore it is less expensive and smaller but takes longer to change bands. There is also less to go wrong with it and, since it is designed to make use of a longer whip antenna, efficiency and bandwidth will be better than that achieved with a screwdriver antenna.

Installation of the remote head of the FT-891 was taken care of with a cup holder mount from DX Engineering.

One other item of interest is the Breedlove stake-hole mount with a 4 degree angled top plate (scroll about halfway down the page). This 4 degree skew allows the mounted antenna to be vertical, compensating for the angle of most pick-up bed rails.

Breedlove hardware isn't cheap but it is very well built and heavy duty, and it is delivered quickly.

I'll use the rig mainly for POTA activations and RV camping in areas that won't accomodate a dipole. This will reach out there with a bit more authority than the KX2.


WB0WQS said...

John, You never fail to find the neatest gadgets for ham radio. Always helping me to spend my kids inheritance. Thank you for sharing this product on your blog. Hope to see something about it on your youtube channel soon. 73.

John AE5X said...

That's what my kids tell me! Inheritance - what inheritance?!

Unknown said...

I am curious if this antenna requires an antenna tuner. If so, what one are you using and is it also mounted under the seat?

John AE5X said...

No, a tuner is not necessary - the antenna is tuned by placement of the tap (inside the PVC collar). I'll post more in the future about how much one turn of the coil represents in kHz on each band.

Unknown said...

good morning what is the diameter of the stainless steel wire of the coil of this river coil antenna attentively
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