Want to check out ATV in your area but don't have a cable ready TV (cable ch 57-60) or need to be right on frequency and with more sensitivity? If you are not ready to transmit yet, then this downconverter is for you. The TVC-4S downconverts the 5 standard USA ATV frequencies - 421.25, 426.25, 427.25, 434.0 and 439.25 MHz - in the 420 to 450 MHz ham band down to your TV receiver on ch 3 or 4 - what goes in at 70cm, comes out on the TV channel. The frequency is locked to a synthesizer crystal reference for accuracy and no temperature drift.

The rear of the downconverter has a N connector 50 Ohm antenna input and 75 Ohm F to the TV set. A DC power jack is used with the supplied 12Vdc wallplug power supply, or you can make a cable for portable battery or mobile operation. We stock a variety of 70cm antennas - download our catalogue page 3 on this downconverter, antennas and ch 3 receiver. The frequency is selected by a rotary switch tuning knob on the front.

This ready to go downconverter contains the sensitive TVCX-4S board with a low noise HJ-FET (less than .4 dB noise figure device) preamp and GaAsfet mixer stage in a die cast aluminum box with 120vac to 12Vdc wall plug power supply or you can run it on external +11 to 14 Vdc at 120 ma by your own DC power cable with a 2.1 x 5.5 DC power plug - Radio Shack 274-1569 - to connect to a battery or other supply. For those that want to upgrade to a more sensitive and temperature stable unit, the TVCX-4S board - $99 - is one for one replaceable with the TVC-2G board found in our older downconverters and transcievers. We also have the TVC-9S 33cm band downconverter for $159 or TVCX-9S board only for $109 and TVC-12S 23cm band version for $159 or TVCX-12S board only for $109.

If you want video and line audio (A/V) outputs to drive a monitor, computer, camcorder, etc., that have this kind of input, add the Rch3 channel 3 receiver...$89. Infact, if you want both types of output, you can put a splitter - Radio Shack 15-1234 or 15-1235 - on the 70 or 33cm downconverter output and drive a TV or TV's as well as a monitor through the Rch3. F jack ch 3 input, RCA jack A/V outputs and comes with wallplug AC power supply. Download the Rch3 app note to add squelch, S-meter and 12Vdc power.

A net can greatly benefit getting ATVers by video show and tell rather than trying to describe something by voice only - "Pictures are worth a thousand words." With ATV you can have full duplex audio - while one transmits and talks on the ATV sound subcarrier, everyone else can watch and listen on their cable ready TV set (cable ch 58, 59, 60) or TV with our downconverter, and at the same time talk back on a two meter FM voice frequency (better interaction and eliminates the long winded). How about setting ATV up at your ham club and transmitting the meeting live or by tape later to those members who cannot attend. The possibilities are endless.

Sending video is easy with your camcorder, video camera, digital camera, VCR, or any device with Video outputs that can output on an A/V cable and be seen in a video mointor, VCR or TV sets A/V inputs. Most camera mic's are amplified and output line audio which can be plugged into the ATV transmitters line audio input.

For more detailed information on How to Get Started on ATV, ATV DX Variables, go to the application notes and download these titles.

70cm Antennas
DX running 20 watts, 100 ft Belden 9913 or Times LMR400 coax can be snow free over 100 miles if line of sight using the Directive Systems DSFO-25ATV antennas at both ends. They are one of the best designed (specifications) high gain (16 dBd) and broadband beams for ATV. 20 Watts is plenty for most all line of sight applications. The hard part, however, is getting line of sight between the two antennas given the curvature of the earth, trees, buildings, etc. Non-line of sight cannot easily be predicted, but how strong a signal is on 2 meter simplex is a good indication that you might have a path - See ATV DX and ATV DX Records.

Note that even with home made ground planes at each end the snow free DX is 6 miles if running 20 Watts. If antenna size is limited for what ever reason, we also have the The Olde Antenna Lab 5 element 5L-70cm beam as shown at right that gives 8 dBd on a 31 inch boom, and 10 element 10L-70cm which gives 11 dBd on a 62 inch boom. Either beam will give you more than the 6 miles even running 1 Watt with our TXA5-RCs transmitter board snow free line of sight ATV which is great for portable or just hitting the local ATV repeater.

CB-35 Low Cost High Resolution 480 line Color Camera....$189

The CB-35 color camera is perfect for the ham shack, but also good for mobile or portable with our ATV transmitters with it's 480 lines of resolution using a 1/3 inch Sony CCD. 768(H) x 494(V) picture elements, .1 lux, AGC built in, >48 dB S/N ratio, switchable back light compensation, automatic white balance, automatic electronic shutter and optional auto iris control. 6mm adjustable focus CS mount lens supplied as well as a 12Vdc @ 300 ma / 110 VAC wall plug power supply (camera draws 150 ma and can run on external +11 to 13.8 Vdc - Make your own DC power cable with a 2.1 x 5.5 DC power plug to connect to a battery or other supply - Radio Shack 274-1569). Camera body is 4.1 x 1.8 x 2.25 inches and weighs 13 oz. NTSC 1 volt peak to peak composite video out BNC connector.

New RTX70-1s 70cm ATV Transmitter

Our last TC70-20Sa ATV Transceiver was sold in April 2007 and unfortuneately, the 20 Watt power modules are no longer being made. To replace it, we are designing the RTX70-1s 1 Watt transmitter which you can add a Downeast 7025PA or Mirage D26N if 40 to 50 Watts pep is desired. Availability should be in May - check our New for 2008 web page. You can also package your own 1W ATV transmitter using our TXA5-RCs transmitter board, FMA5-G sound subcarrier board and TR-1b RF T/R relay board. See the application note with parts list and die cast aluminum box drill drawings.

Over the years we have gone back and forth between having available a transceiver or a transmitter that would pair up with a downconverter. The demand has always been about 50-50. So now we will go back to Transmitter plus downconverter. The advantage of using a separate downconverter is that you dont have to get a downconverter to use at the receive end of a public service event as you might if you only owned a transceiver. Also some areas may only operate through a crossband repeater and very little simplex. Separate units also offer a lower entry cost to 70cm ATV since a cable ready TV can be used initially to receive.

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Hams, down load the catalogue pdf files.
Email us - - with your call letters if you have any questions not covered in this web site.