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2000 Jetta TDI

Returning from Dayton, 2007
AA1K on the road
The AA1K mobile on I-470 near Wheeling, W.Va. (Thanks N2YO)

On the road

With an hour-long commute from central to northern Delaware, I do lots of mobile DXing.
My first mobiling came in the late 1960s while in college, using a Lafayette HE-45A six-meter monoband AM rig in a Triumph TR-3.
I did my first HF mobiling in the early 1970s when I also had an hour-long commute from West Chester, Pa., to Fort Washington, Pa. This was with a Yaesu FT101B in a 1973 Volkswagen Beetle, with a Hustler center-loaded whip or a helical whip for 40 meters on the rear bumper. I quickly discovered how easy it was to work DX from the car with CW.
In 1975 I acquired a Volkswagen Camper and installed a mount on the roof with an 8-foot whip -- pushing the limit on bridge clearance. A coil and rotary switch between the roof and ceiling provided all-band operation. This was used effectively on my travels in the western USA and to Alaska.
With more VHF activity and shorter commutes, I got away from HF mobiling for a few years until an hour-long commute -- often late at night -- returned in the late 1990s. I acquired an IC706 MK2 (later replaced with an IC706 MK2G) and used this with several Pro Am monoband whips mounted on the roof rack of the Jeep.
RFI issues
The Jeep suffered from serious ignition noise, typical of most gas engines, although the 706 noise blanker did help some.
Purchase of the 2000 Jetta TDI with it's diesel engine brought much better fuel economy and the added bonus of an extremely low noise floor since the diesel uses no spark plugs. The car, however, was not totally RFI free. While the car had it's low beams on day or night -- daylight running lights -- when I switched the lights "on" enabling the taillights as well, the higher bands (especially 10 and 15 meters) suffered from birdies every few kHz produced somewhere in the VW electronics and no doubt coupled to the screwdriver antenna mounted a half a foot or so from the taillights. Since these tend to be daytime-only bands, I never got around to finding the source of this noise and trying to filter it. I did put some ferrites on the taillight wiring but this didn't help much.
The other RFI issue with this vehicle was on 40 meters. If I transmitted with 100 watts output, some RF got into the speedometer circuitry and shut it down. The car would still drive fine but I just wouldn't know how fast! The cruise control would of course stop working, since that depended on the speedometer. Since I was usually using the cruise on the open road, this was a nuisance. I found if I reduced power to about 30 watts, the RFI problem went away.
Otherwise this car had an extremely low noise floor, especially on 160 and 80 meters. It was not unusual to be able to copy weak DX signals on Top Band while on the Del. 1 expressway, with few adjacent power lines, that base stations with bigger antennas could not hear.
I had upgraded the antenna on the 2000 Jetta around 2002, replacing the monoband ProAm whips with a KJ7U screwdriver. It took me a while to get the antenna transferred over to the new 2009 Jetta, which is VW's new "green" technology, and operation was then delayed for most of the 2009-2010 winter till I did some refurbishing of the antenna.

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The homebrew mount

My heavy-duty, long commute mobiling has been done from a 1991 Jeep Cherokee (1998-1999), a 2000 Volkswagen Jetta TDI (2000-2009, shown in photos) a 2006 VW Jetta TDI (early 2009) and a 2009 VW Jetta TDI (July 2009 to present), purchased new in March of 2000. All but the Jeep have had a diesel engine so no ignition noise. I put about 35,000 to 40,000 miles a year on it, and it had 321,877 miles when I sold it in early 2009 and new owner says it is still going strong.
54 countries worked on 160 meters, and 277 countries on all bands.

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The KJ7U screwdriver and homebrew mount

I use an Icom 706 Mk2G as the main radio. This covers 160m through 70cm. I have a separate Icom 2100H for 2 meters.

The main antenna is a KJ7U screwdriver for 160-6 meters. This was the only commercial screwdriver available when I bought it that would cover 160 with continous tuning; others required getting out of the car to insert a separate loading coil. It sits on a hombrew mount sticking out below the rear bumper.

I do mostly CW from the car, with a small Vibroplex paddle sitting on the passenger seat (or wedged in below the brake lever when I have a passenger).

I have a 5/8-wave 2-meter whip for the IC2100H permanently mounted in the roof just ahead of the moonroof.

A dual-band magnetic mount MFJ which for 2m/70cm allows the IC706 to be used on those bands when desired.  

The chassis of the New Beetle, Jetta and Golf are the same.  Just below the rear bumper, on the right side, is a towing ring. This towing ring is attached to the body via a piece of U-channel steel welded on during manufacturing of the car. This channel conveniently had a hole of about 3/8-inch already drilled in it. I used that hole and the towing ring to use two bolts to attach a piece of galvanized angle steel that is long enough to stick out about 5 inches beyond the bumper. I initially had a lightweight version of this -- using 2" by 2" angle stock -- which held a 3/8-inch antenna mount and I used various Pro-Am monoband whips on this. This bar was mounted below the tow ring -- and it hung low enough that it would scrape going into some parking lots. Later when I bought a KJ7U screwdriver antenna, which is quite heavy, I rebuilt the mount using 3" by 3" by 1/4-inch thick angle stock, and contoured the steel so it would slip in above the tow ring to allow better clearance. This has handled the screwdriver antenna quite nicely for more than four years and 200,000 miles, and gives me continuous tuning from 160-6 meters.

For power, I ran a piece of RG8 coax from the battery, under the vehicle, and up into the luggage area through a convenient rubber grommet near the right rear wheel well. I kept the main body of the IC706 loose in the luggage area for the first three years, then finally mounted it permanently to the steel under the shelf below the rear window (this is not there on the New Beetle or Golf). I run cables -- for the key (yes, I do mostly CW), remote front panel, speaker and control for the screwdriver antenna -- between the rear seats and along the hump up to the front dash. I mounted the toggle switch for the screwdriver antenna on one of the dummy panels for a switch that was used on other models.

The coax and screwdriver control cable can either be run through the same grommet as the power cable into the luggage area, or just directly into the trunk and the trunk lid closed on them. I do the latter with the screwdriver control cable, and I have not had any problems with it.

I run a separate 2-meter radio in the Jetta, and my wife's (AB1P) New Beetle (2001) has only a 2-meter radio. Both vehicles have sunroofs, so roof space for a 2-meter antenna was limited. For a while on both we used magnetic mounts, but eventually the door would chafe the coax and it would need replacement. Finally I bit the bullet and mounted an NMO mount on the roof about halfway between the front windshield and the moonroof. This area is accessible by removing the controls and motor for the sunroof. I snaked the coax along the front of the headliner and down along the pillar on the right side of the windshield, then up under the dash.
On Jeanie's new car, a 2006 New Jetta, the 2m rig was squeezed in in front of the gear shift in the center console, and a 1/4 wave whip with a trunk-clip NMO mount was used on the passenger side of the trunk. It fit best on the vertical portion of the trunk, next to the tail light, and the antenna was bent at a right angle to go vertical.

To power the separate 2-meter rig, I snaked the power cable beneath the dash (use a torx driver to take off the panel below the steering wheel) and used a stiff wire to push it through the firewall alongside one of the wiring harnesses, on the left side of the vehicle behind the battery, and wired it directly to the battery.

I just use the standard battery, but it is huskier on my TDI than on the gas models.

With the diesel there is no ignition noise. I get some "birdies" about every 1 kHz from the VW electronics on 20-10m when I have the taillights on (the headlights are always on). Also, if I transmit with 100 watts on 40 meters, RFI shuts down the speedometer -- and thus the speed control unit. It recovers when I stop transmitting though. No problem with this if I cut power to 30 watts, and this is only a problem on 40 meters -- no trouble on other bands.

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Beetle tow ring