K5LXP's "No Holes" HF Installation

Virtually No Holes HF Mobile Setup

All photos are clickable for a larger view.

HF Operation

For long trips I've got an Icom IC706 that I made an almost no-holes installation for. The control head, Yaesu ATAS-100 remote antenna control box and audio mixer control box all mount to a wooden affair that merely fits between the seats. The transeiver and antenna control box are remotely located from the driver's position to the rear passenger seat, and since it's not intended to be a permanent installation, they just rest on the floor. A custom bracket mounted to the steel underpinning of the rear bumper hold the Yaesu ATAS-100 HF mobile antenna, which can quickly be removed when not operating. The only hole drilled was a 3/4" one throught the plastic rear bumper.

Here is a shot of the driver's position: 706 control head, antenna control and audio mixer box.
This shows the wooden support as the boxes, brackets and speaker are attached.
Here is the transceiver and ATAS antenna control box.
Here's the travelling configuration. The 2nd 2m antenna is a mag mount connected to the VHF antenna port on the 706. It was cheaper to add a 2nd antenna than buy a diplexer to use the ATAS-100 for VHF.

This is the Yaesu ATAS 100 HF mobile antenna, and copper mast extension that I designed and built.
Here is a view from under the car showing details of the quick-remove bracket attached to the plastic bumper's metal frame. A clamp-on ferrite bead was used to minimize RF on the coax shield.

Detailed Description
After numerous HF mobile "expeditions" I've refined my setup a bit to make operating more convenient. The first accessory I built was a passive audio mixer and speaker control box. It connects to the HF and 2M rig's speaker connections. Using the mixer box I can route either radio to the main speaker, or turn it off entirely. Using the mixer pot I can adjust the levels of each radio to suit into the headphones. Both stereo and mono headphones can be accomodated. This box makes monitoring two radios much simpler, and the speaker cutout switch improves relations with the XYL on long trips. The other accessory I made is a remote switch for the ATAS antenna control box, so I don't have to route the coax to the front seat just to control the antenna. The antenna bracket itself is a piece of 8" steel pipe with a PVC cap on one end and a steel cap on the other. The PVC cap has a 3/4" hole, and the steel cap has a chassis mount N connector. I made an RF "adapter" out of a piece of 3/4" copper water pipe with an N connector at one end, and an SO-239 at the antenna end. This extension brings the antenna up to the level of the trunk lid to minimize interaction to the vehicle. Antenna removal is as simple as unscrewing the mast from the hidden bumper bracket and covering the hole with a painted cap.

AF Mixer 29KB JPG
Earbuds 66K JPG
Homebrew Passive
Audio Mixer Control
Koss "The Plug"
Earbud Headphones

The other accessory I've found to be very useful are these Koss "The Plug" earbud headphones. These headphones are similar to regular walkman-type earbuds but feature earplug style cushions. This cuts way down on ambient wind and road noise in the vehicle which improves the intelligibility of weak/noisy HF signals. These units also feature decent fidelity which also helps intelligibility.

In short, this is the nicest HF mobile setup I've ever had. The 706's DSP filter and noise blanker really help squash the vehicle EMI and QRN, and the ATAS-100 is a godsend compared to stopping at the side of the road to switch Hustler coils. After a few hours of operation I didn't even need to transmit to verify the SWR, the antenna's tuning peak is fairly abrupt and easy to detect and adjust based on receiver background noise and signal strength. The ATAS-100 is kinda pricey when you throw in the tuning box, but it's small size and finished appearance were more important than the modest efficiency improvement offered by the larger and less aesthetically pleasing screwdriver antennas out there.

Military "leg mount" mini clipboard with night light.

The best five bucks I've ever spent at a hamfest was to get this nifty military leg strap clipboard. It has a built in red night light and spring loaded clamps at both ends, plus a couple of pencil holders. It saves a lot of fumbling to log that rare mobile contact, and also allows you to log while driving at night, which is the time of day most of my trips seem to happen.

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