While this post is not about the reception and logging of commercial TV stations from a distance, it is about the transmitting and reception of UHF analog signals over a good distance considering the power levels used.
I hope some of the forum members that are interested in TV dxing might like to read about this activity from another perspective... the transmitting side.
I participated in the transmission and reception of UHF analog TV signals (439.25Mhz) over fairly long distances to other similarly equipped stations, here in the midwest, back in the '80's. Back then, most stations were equipped with tube-type transmitters. Solid-state had just begun to be available, but it was expensive and fairly low powered. Cameras were mostly B&W, color was used but was sure a lot more expensive.
Summertime was best for the long distance shots... sending our comparatively weak signals across state lines for several hundreds of miles. Summertime brought the temperature inversions we used to skip our signals to far away receivers. We patiently waited for the hot summer days to cool off towards nightfall... hopefully without winds that would ruin the forming of the inversion layers.
To make up for power levels far less than commercial TV stations used, we made very directional, high gain yagis and placed them as high in the air as possible. We fed the antennas with very low loss runs of heliax. We tried to squeeze as much power as we could from our tube amplifiers to go the distance.
On the receive side, most of us used very low noise "gaasfet" preamps before the TV monitor to extract the most signal we could get from the station at the other end.
We co-ordinated our activities between each other using 2 meter FM, because we could always be heard at a distance at a stronger level than the TV signal we were sending at UHF.
When conditions were good, we were able to send live (fast scan) TV over several states to other operators here in the midwest region. It was a lot of fun getting to see the person you were talking to live on your own TV set!
From my location in Indiana, conditions permitting, I had my signals viewed from and received:
downstate Indiana, Illinois, Iowa, Wisconsin, Michigan, Ohio, and St. Louis Missouri.
That's "quite a haul" for a transmitted signal... roughly 50 watts of wide bandwidth UHF!
I kept a record of all that activity back then by taking a screen shot of every station that appeared on my TV. I still have those pictures in a photo album. Many of those ops have (sadly) passed away.
I'm glad I had participated in that group back then. Some of the "mentors" that got me started were "old-timers" that pioneered the mode (ATV) from "day one". They built all of their own equipment from scratch... even down to the machining of amplifier hardware. Of course, most of them were either electronics engineers or military radio operators. I was fortunate to know them.
Well, times have changed with the digital age of TV. Just like every other phase of the wireless hobby.
Still... best dx to you!
Topic: TV DXing from the transmitting side of the hobby (Read 5579 times)