Have You Ever Tried Amateur Television?
Years ago when I first got on ATV about the mid 1960’s it was a major undertaking and had to be a labor of love. Almost everything was still tubes and power supplies were big and bulky. Preamps, converters, transmitters, the TV set and the TV camera all glowed in the dark. Then getting things to work properly in the 70cm band was only for those that had lots of patients and a burning desire to experiment in the realm of Television. Antennas of then and now are basically the same.
The preamps employed the ‘old standard’ golden grid 416B vacuum tube. The final amp in the transmitter was usually a 2C39 planar triode or commonly referred to as a ‘lighthouse’ tube because it looked like the ’lighthouses’ of yesteryear. The cameras employed, ‘image orthicon tubes’ that was terribly light sensitivity. We didn’t have the automatic iris shutdown circuits of today’s cameras and if the orthicon were to ever inadvertently be pointed at the sun you could kiss it good bye.
Power output was low, distances were short and stability of all of the stuff was questionable. Transmission line (coaxial cable) wasn’t as good then as what we have today. The connector of choice was the PL259/SO239 combination. If we wanted to transmit a test pattern it was usually printed on a sheet of cardboard and held up in front of the camera. Oh yes, and everything was black and white. I know, some of you can’t remember when there wasn’t color, and in a few years a few will be asking what was analog, as we enter this ‘high definition’ age of TV.
Well folks, things have changed over the years and definitely for the good. Today we have CCD cameras that contain their own batteries, they have on screen titling and editing, a myriad of features that hadn’t even been thought of in the 60’s. We used to have to ‘white balance’ our cameras by holding a sheet of white paper up in front of the camera in order to tell the camera what white looked like. Even up to say ten yeas ago there were still some Saticon Cameras available (the old Sears 3000 series) that had to be ‘white balanced’ every time they were powered up.
Now all that is involved in getting on ATV is the family CCD Camcorder, a solid state, frequency synthesized (no more crystals to buy) transceiver, portable TV set and an antenna. An added feature might be a test pattern or video overlay box to put your call sign in the televised field you are transmitting or a test pattern with some logo of your choice.
As for distances, I have a friend in Birmingham, AL that runs ATV tropo contacts with hams in the Chicago area. True, we don’t enjoy a lot of tropo out here (Colorado) but we do have some high places that afford us some fairly fantastic VHF/UHF DX contacts. In the near future we should have an ATV repeater functional on Pikes Peak that should cover a goodly portion of our state.
I’d be glad to answer any questions on ATV or you can visit the P.C. Electronics Web Site; www.hamtv.com where you’ll find equipment, prices and app notes on about any possible aspect of Ham TV. CU 73, Dave…(W6OAL)
Dave W6OAL –
Olde Antenna Laboratory 41541 Dublin Drive Parker, CO 80138