Ham TV – Amateur Television

Receiving ATV
ATV off air receive pixHave a close by ATVer transmit a picture to you or come over with a low power transmitter to help you set up your TV. Most TV’s since 2008 have to go through a set up scan looking for active over the air or cable channels. The tuners in the TV’s sold in the USA are required to work with analog as well as digital signals. Connect your TV to an outside 70cm antenna with the same polarity as used by your areas ATVers and run the scan for the signal. You can talk back on two meters – usually 144.34 or 146.43 simplex to line up antennas and make the tests. If successful, you will hear them on the sound subcarrier coming out of your TV speaker. It does not get any cheaper than this to check out the ATV action. The TV 75/50 Ohm coax-antenna miss match is negligible and you can use a F to N connector adaptor. If you have an old analog TV tuner, select cable channel 57, 58, 59 or 60 depending on what frequency is used in your area – cable channels are on different frequencies than the old analog over the air broadcast channels. Cable channel 60 is in the 70cm ham band at 439.25 MHz, over the air broadcast UHF TV channel 60 is 747.25 MHz, and each channel is spaced by 6 MHz. The TV tuner should lock on, even if off a MHz – the off the TV screen photo at right is actually transmitted 3/4 MHz higher than cable channel 59. Antennas are the key, so good coax and mounted as high as possible to get line of sight will work best. You can build an antenna or buy one like in the antenna section below.

It is best to select a TV that does not go to blue screen or automatic shut off when there is a snowy picture or no signal present. You dont want the TV to shut off while monitoring a local ATV repeater, searching for DX or aligning your beam. Some TV’s require reprogramming the active channel memory so that you can use cable channels 57-60 or channel 3 or 8 if using a downconverter for the 900 or 1200 MHz bands. The easiest is to connect the TV to your Cable TV service if analog, then push the channel program button in the CATV mode. This should set the TV up to select most all channels even when no signal is present when no ham is on the air at that instant. New TV’s will contain an analog NTSC cable channel tuner in addition to digital channels per FCC Rule 15.118(b) to accommodate all cable TV systems, but it is a good idea to keep your old analog only TV’s for ATV work rather than trash them when you buy a new digital TV.

A net can greatly benefit getting ATVers by video to 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 – see our ATV application notes web pages.

ATV receive systemWant to check out ATV in your area but don’t have a cable ready TV (cable ch 57-60), or see a local repeater output that is on the 900 or 1200 MHz band? Then you need to add a downconverter between your antenna and TV that will convert the higher ham bands down to a TV channel. What goes in at the ham band is mixed down to come out on the TV channel. 70cm and higher band Analog ATV will be around for a long time due to the high cost and complexity of transmitting Digital ATV and the fact that new TV’s must also have analog cable tuners in them per FCC Rule 15.118(b). However, a downconverter will work for both analog or digital ATV – which ever mode goes in, comes out at the downconverted channel. Current manufactured US TV’s have tuners that will work with cable channel analog or digital QAM, as well as over the air broadcast ATSB 8-VSB. We no longer manufacture ATV downconverters, but you may be able to find some of our prior model TVC series downdownconverters on eBay and QRZ.com On Line Swapmeet.

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