I have been an amateur radio operator since 1964 and have held an Extra class license since 1968. I have always been fascinated with HF mobile operation and with slow scan TV (SSTV). I first got started on SSTV in 1970 with a homebrew 5FP7 radar CRT monitor and progressed through the Robot 70/80 analog SSTV system and later the Robot 400 digital scan converter. About 1979 I made my first attempt at running SSTV mobile. I used the Robot 400 converter with a Sony 5" B&W TV as a monitor and a B&W vidicon camera from a deceased open-reel video recorder. The camera was mounted on a tripod standing on the floor in front of the passenger seat and looked out the windshield. This entire assembly was powered by a Heathkit MP-10 12VDC-to-110VAC inverter and was connected to an Icom 701 HF transceiver. All this was crammed into a 1977 VW Rabbit. I managed, sort of, to televise the 1979 Iowa City Marathon to a total audience of about 5 SSTVers on 20 meters.
In 1998, Kenwood introduced the VCH-1 "Interactive Visual Communicator". This device is a complete SSTV system including a 1.8" color monitor, color camera, SSTV decoder/modulator and scan converter; all packaged in a slightly oversized hand-held speaker-mike case. The appeal of this device was irresistable! Finally practical mobile SSTV ! Just point the thing out the window, fire at the passing scenery or traffic and send "LiveCam" images over the air... [ LATE UPDATE: Kenwood discontinued this product as of December 2003. Probably one of the reasons being the supporting software only worked on Windows 95/98. As Windows 2000 and XP became the dominant operating systems on home and ham shack computers, Kenwood most likely decided it wasn't worth redeveloping the software for this slow-moving product and and killed it instead. ]
About the same time, purely software-based systems appeared that use the sound card of a PC to receive and send SSTV pictures. Since just about every ham shack now has one or more computers, a freeware program and sound card connections to the radio's mic and speaker are all that is now required to operate SSTV. Previously hundreds or thousands of dollars of specialized hardware was required. The popularity of SSTV has exploded as a result.
The pictures below show my mobile SSTV setup installed in a 1997 VW Passat TDI Turbodiesel wagon. [Note: This has been superseded by the next install in a 2006 Jetta TDI -- details here .] Details of the mobile table assembly shown in the pics below is on a separate page here. I use a Yaesu FT-100 HF transceiver and a TM-742 6M-2M-450 triband VHF/UHF transceiver. A Kenwood TM-D700 2M-450 transceiver with built-in packet modem (TNC) transmits APRS (Automatic Position Reporting System) data. A small Sony digital camera (DSC-F1) mounted on the passenger-side visor serves as an external video camera for the VCH-1 for "LiveCam" shots of the road ahead. On HF, I use either of two antenna systems. On cross-country trips I use an SGC Smartuner 230 QMS (Quick Mount System) on the roof of the wagon for 160M thru 10M coverage. The attached whip towers 9' above the roof of the car and has to be folded down frequently in town. I wanted something lower profile for everyday in-town use. Most of the time a Yaesu ATAS-100 autotune mini-screwdriver occupies the same real estate on the roof that the QMS does on trips.
I have recently replaced the Sony Digicam with a tiny
CMOS CCTV camera. This camera, less than 1" (2.5CM) square,
operates on 8-15 VDC at less than 10mA and outputs standard NTSC composite
video usable directly by the VC-H1. It even contains a very sensitive
electret mic element (which I don't use). It is made by Swann
Electronics of Australia and is available in the US for under USD
$40. It is available at Fry's Electronics (California retail stores)
or by mail order from Tiger Direct at http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1356155&CatId=1322
. Or search for "Swann SW-P-DSC DIY Color Security Camera"
Yaesu's ATAS-100 "Active Tuning Antenna System" is a motorized-coil "screwdriver"-type antenna tuning continuously from 40 thru 6 meters in an assembly only 4 1/2 feet tall. It also works on 2M and 70cm ! The motor in this antenna is powered by DC voltage fed into the coax feed line by the transceiver. The antenna normally only works with Yaesu FT-847, FT-100 and FT-857 transceivers which have the DC coupler and control interface built-in.
After studying how the interface works, I have home-built a control box that allows the ATAS-100 to be used with any radio. Basically, if you insert more than +8.5 volts into the coax (direct "12 VDC" from the car battery), the coil tunes in one direction. If you insert +8 volts or less into the coax, the coil moves in the opposite direction. No negative voltage is required. My coupler inserts in the feedline between the transceiver and the antenna. It feeds DC toward the antenna while blocking it toward the radio, and blocks RF from backing up into the DC power source. After several tries, I arrived at a physical layout that is essentially lossless (< .1 dB loss from 1.8 MHz to 460 MHz) and has a minimal effect on SWR (< 1.2:1 from 1.8 MHz to 460 MHz). A double-throw center-off momentary-on switch in a control box next to the driver's seat supplies either direct battery voltage ("13.8 VDC"), or the output of a 7808 3-terminal regulator to the coupler which is installed under the car's rear seat.
Quoting from SGC's website:
Normally, you use one 54-70 at the shack end of the coax to combine RF and DC; and a second one at the coupler to separate the DC again. The devices are sold in pairs for about $100. For the ATAS-100 application, you would only need (at the radio end of the cable) since the ATAS-100 does it's own DC separation at the antenna. You would still have to provide a source of selectable 8VDC/12VDC to feed into it. I have swept and measured the 54-70 and found it has less than .2 dB loss per pair up to 52 MHz and about .5 db loss at 146 MHz.
Pictures below show the electrical and physical details of the ATAS-100 and my coupler.
Since I acquired the "DC-to-light" Yaesu FT-100 transceiver, I have wished that the SGC QMS automatic antenna tuner system could cover VHF and UHF in additon to 1.8-30MHz. I modified the SGC to do just this. I added an aluminum plate to the top deck of the QMS box, that sticks off the rear of the QMS about 8 inches. In the center of this plate, I installed one of the heavy-duty Comet SO-239-socket through-roof mobile antenna mounts. I screwed a Comet SB-14 52-146-440 MHz tri-band whip into the socket. A Comet CF-360 duplexer, mounted under the expansion plate, allows a single coax to feed HF to the Smartuner and VHF/UHF to the Comet whip. Although the two whips are parallel and only about a foot apart, there seems to be no interaction. On HF, of course, the tuner just automatically accommodates any capacitive loading caused by the Comet antenna. This assembly, which I call my Smartuner QMS-FE (for Frequency Expansion), provides an instantly-mountable antenna system that can work over the entire range of the FT-100 or a Icom 706.
Pictures below show the details of the "QMS-FE"
These pictures were shot with a Sony DKC-ID1 768x580 digicam and a Sony D700 1344x1024 digicam.
Click Thumbnail Images At Left For A
|A shot of the Passat showing the SGC Smartuner system on the roof. Antennas from front to rear: Comet 2M-70CM-800 MHz tribander, Larsen 6M baseload, SGC Smartuner 230, Fuba AM-FM OEM whip, and finally a GPS patch antenna.|
|Normally the QMS mounts to the roof with suction cups and straps. The scheme allows a no-holes installation on any vehicle on a moments notice (hence the Quick Mount designation) but is a nuiscence to attach and detach with much tugging and tightening of the straps and prying of the suction cups. I have replaced the straps with a pair of oak bars that lock to the Passat's OEM luggage rails with modified U-bolts.|
|The SGC Smartuner after being modified to a "QMS-FE" frequency-expanded version that now covers all the frequencies that the Yaesu FT-100 operates on. See writeup above on the frequency expansion mod.|
|An animated GIF showing how the bars lock down almost instantly using the j-bolts. Note how the rubber pad I glued to the bar wraps around the cargo rail as the J clamp rises, creating a completely non-slip grip. I can install or remove the entire system in less than 2 minutes now.|
|A pair of Smartuner QMS-FEs used in a fixed station location. Note the 90-foot copperweld long-wire connected in parallel with the whip on the nearer unit to improve performance on the 1.8 and 3.5 MHz bands. These two antenna systems serve 6 ARES/RACES frequencies simultaneously (Each system works on 28 or 50 MHz with an Icom 706, on 146 with a Kenwood TM-241 and on 450 with a Kenwood TM-441 coupled through a Comet triplexer.)|
|I modified U-bolts into custom J-bolts with a hacksaw for use with the mounting system.|
|The QMS system is self-contained in a heavy aluminum box and must be grounded to the car body at some point. I sleeved the provided braided-strap ground cable in a piece of 1-inch shrink tubing and stretched it about 1 foot into the tail-gate opening. It is screwed down to a 1/4-inch stainless bolt I installed in the tail-gate lip. The 3/8-inch long bolt allows barely 1/16-inch clearance when the tailgate is closed.|
|The Yausu ATAS-100 mounted on my roof --- a lot lower profile than the Smartuner (but it doesn't go down to 160M!). See animation below.|
|Interior view of the mobile SSTV installation. The Kenwood VCH-1 is lying on the seat next to a mic. TM-742 VHF/UHF tribander is in the console pocket. The Yaesu FT-100 control head is mounted to a piece of plywood cut to exactly duplicate the dimensions of the factory ash tray which is inserted into the ash tray pocket in the console.. I run Delorme Street Atlas with a GPS display, and the WinPix SSTV program on the PC at the same time. I can view the incoming SSTV images simultaneously on the PC and the VCH-1.|
|Mobile "LiveCam" is a Sony DSC-F1 digital camera with NTSC output being used as a TV camera. The video output of the DSC-F1 is fed into the external video input of the VCH-1 scan converter and is far superior to the VCH-1's own video camera.|
This incredibly small CMOS CCTV security camera is the "LiveCAM II" replacement for the Sony digicam described above.
|This single tiny PCB is the entire inside of the camera. The chip with the glass window that looks like an EPROM is the CMOS image sensor. "Tip" and "Ring" labels in the full-sized image refer to the connections for the camera connector on the Kenwood VC-H1. I replaced the factory-supplied cable (that had two RCA plugs and a coax DC power jack) with a 10-foot (3M) cable with a single 3.5MM stereo miniplug. This allows the camera to plug directly into the VC-H1.|
|The "LiveCAM II" as mounted in the car. I built a homemade bracket to clip it to the passenger-side sun visor. Swinging and tilting the visor lets me pan and tilt the camera without having to touch the camera's bracket at all. With the visor swung all the way to the right (parallel to the passenger side window), the cam gets a perfectly framed shot of the driver. With the visor folded up against the headliner, the camera is nearly invisible from outside the car.|
|Close-up views of the ash-tray mounting adapter for the FT-100 head. The piece of 1" plywood is covered with a piece of rubber matting for a non-slip fit.|
|A small home made switch box wedged between the console and the passenger seat transfers the VCH-1 connections between the two radios, provides audio input/output to the PC, and supplies 6 VDC power to the VCH-1 (saving its batteries).|
|I crammed a lot of stuff into the box! It also contains audio detectors to key the transceivers when the PC generates SSTV tones (basically a VOX circuit).|
|3 SSTV images I received while cruising Interstate-70 near Grand Junction, Colorado; one from Washington state and two from Michigan.|
Kenwood VCH-1 Video Communicator
|Inside view of VCH-1|
|Close-up view of interior showing the VCH-1 uses the same chip as is used in the stand-alone TASCO SSTV scan converter.|
Interior Views of Kenwood TM-D700 146/440 Dual-Bander with built-in TNC
|Traditionally the digital circuits (microprocessor controller and synthesizers) and analog audio/RF circuits of transceivers have been on separate boards often in individually shielded enclosures. The Kenwood TM-D700 transceiver is the first radio I have seen where absolutely everything (RF, audio and digital circuitry) is on a single PC board nestled in a massive casting. The round hole in the casting normally holds the speaker shown to the left in this picture. This shot is from the top and rear.|
|This shot from the front and bottom of the radio shows how all the front panel connectors are mounted directly to the one-and-only PCB. The only non-PCB wiring inside the radio are the DC power cord and the speaker leads! Left-to-right the connectors are: mic jack, control head jack, standard TNC audio I/O and ptt (the radio has connections for an external TNC even though it has one build in), GPS NMEA data in, and finally RS-232 to/from the built-in TNC.|
|A very large 1344x1024 pixel high-res shot of the PC board showing the enormous number of surface mount devices on the board. Normally, I don't expect to see this density of SMDs on a board this large (I would expect this density on much smaller boards in cell phones, hand-held transceivers, digicams, etc). This is a large (403K) JPG image.|
|Schematic diagram of the ATAS-100 DC coupler interface.|
|Exterior view of the coupler assembly.|
|Interior view of the coupler. I placed three layers of single-sided-clad PC board over the shafts of the BNC jacks to raise the ground plane to just below the piece that is visible, and then bridged the center pins of the BNCs with the 4th piece with the slit in it that you see. This created an almost perfect constant-Z transmission line!|
|Animated GIF of the ATAS-100 mounted on my car moving through all the bands from 6 meters to 40 meters. The control box works! The whip above the coil in the rubber bellows is about 36" long. The mast below the coil is 16" long. The bellows varies from about 4" on 50MHz to about 11" on 7 MHz. The overall height varies from 56" to 63".|
|The base of the ATAS-100 terminates in a recessed PL-259 plug. This is a closeup of the heavy-duty Comet through-roof SO239-socket mount used to support the antenna.|
|An exploded view of the components of the mount. The mount and washer at the right are inserted from the under side of the roof through a 5/8-inch hole. The washer and O-ring on the left screw down from above and create a water-tight seal. I reinforced the mount by sandwiching a one-foot-square piece of .090-inch aluminum plate with a 5/8-inch hole in it between the lower washer and the underside of the roof sheet metal.|
|Mr Jun himself of Jun's Electronics in Culver City, CA who let me make extensive measurements and experiments with the ATAS-100 in his store before I bought one.|
SGC Cat #54-70 "DC Coaxial Line Isolator"
|This SGC DC isolator is a commercial alternative to my coupler. This device allows DC to be combined with RF on a coax line at the shack end. A second unit used in the opposite direction at the antenna end allows the DC to be separated from the coax to power an antenna coupler or preamp. The device is usable up to 6 meters with less than .3 db loss for the pair. The top unit has it's cover removed to show the potted moisture-sealed toroidal coils inside.|
SGC Smartuner "QMS-FE"
|Top view of my SGC "QMS-FE" (Frequency Expanded) Smartuner. The added semicircular aluminum plate is a quarterwave radius ground plane at UHF. The distance from the Comet SB-14 whip's socket and the far side of the original QMS box is a quarter wave on 2 meters providing a resonant ground plane on both bands.|
|Bottom view of the "QMS-FE add-on showing the Comet duplexer and SGC DC isolator mounted under the plate. Note that the original 12" coax lead with a PL-259 that came out of the duplexer was removed. The cable on the Comet coax socket was cut down to about 9" and soldered directly to the PC board. The hole the cable passes through was sealed with GE silicone rubber. The silicon rubber was also used to glue the duplexer and isolator to the underside of the aluminum plate.|