The Pioneers

We were the Pioneers

 
The first TV relay station was at Kronach

The first TV relay station was at Kronach Radio waves spread out in a linear fashion like light. This principle applies more strictly the shorter the wavelength. Because of this TV reception is poorer in mountain valleys the further away from the TV transmitter and the narrower the bottom of the valley. This does not suit the technician in the Kronach region as customers mostly live in valleys. In this situation he has to deal with the problem of theTV waves are deviating from their direct path.
Rotatable antennas with wave mirrors were ocasionally built. This solves an individual problem but how does one solve the problem of a whole town if the transmitter is 200 km away?
The Loewe Opta TV team busied itself with these considerations at the beginning of 1953. The Feldberg TV transmitter in the Taunus is 210 km away as the crow flies. The field strength which can be expected with 10 KW senderleistung and twelvefold antenna was way below the limit of what could be expected in the valleys. But the Loewe Opta engineers were very keen to test their TV sets as soon as possible with real transmissions. Because that the company-owned sender N - N - H (never home) gave errors and no more screen sequences could be seen only picture errors. So they sysetematically looked for a place high enough up in the mountains in the Frankenwald and in direct line of site with the factory in the valley. Finally they found a point on the crest of Radspitze about 8 km as the crow flies from the factory about 700 m above sea level. Here they built a wooden hut, just large enough for the equipment and a few people. The receiving antenna was a 4 element dipole hanging on an 8 meter long wooden pole secured with clothesline. Thus they achieved a middle signal level of 0,5 mVs, which was sufficient for stable reception,




The first TV repeater station. It was envisaged of course that the interference between the recption and the transmitter antennas is only avoidable if the retransmission is on a different channel that the received one. That is the philosophy behind channel translators that are nowadays called repeaters. The television broadcast received with 195..... 202 mc/s and is rebroadcast at 216... 223 mc/s and a Watt of power. Perfect reception is achieved with direct line of sight in the valley with a middle strength of from 0,2 to 1m V/m if one ensures that the frequency conversion process occurs without distortion of any kind or voltage fluctuations. That sounds simple but it is a technical problem more advanced that those experienced in home TV sets. The repeater itself has almost as many tubes as the TV receiver. The antenna is a 4 element dipole with parallel and series connection to a 300 ohm balun. Because it was simply nailed to a framework it received the nickname of the "mattress" The mattress was configured about 2 wavelengths on a wooden pole and was pointed in the direction of the factory's receiving antenna
The Power Supply: The mountain drops on one side to a small settlement the houses of which are connected to the power grid.Even thought the distance to the peak was over 500 m in a short time an overhead network of cable was installed over the fir trees and over the steep rocky slope to supply the area with power. An electonic timer device switched power on automatically during transmission times so that the relay station does not need to be manned. Anyhow the people of Kronach if they have TVs with suitable antennas can share in TV broadcasts from Frankfurt. The Federal Postal administration saw no technical problems with this installation and Kronach repeater was assigned a permanent frequency.
On a July evening we drove up to the station. As I stood in the hut and the tubes of the Iris lit up (The Iris is the first Loewe Opta table TV set built in 1954) and the NWDR test pattern appeared I automatically thought about the first December days of 1901 in St John in Newfoundland. Here sat Marconi with his three assistants in a similar small wooden hut in front of which temoprary antennas were mounted on wooden poles. The receiving apparatus would have seemed primitive by today's (1953) standards. The only difference was that we awaited TV reception from an improbably great distance, while Marconi waited for the prearranged sounds: dot dot dot dash that would come from the remote station Poldhu in Cornwall. After three day-long futile attempts it finally came on 12 December 1901. The predictions of the world's best scholars had been put paid to - that radio transmission over sea could never succeed because the earth is a sphere. Also in the hut on Radspitze a misconception was buried - that was believed since the Stokholm conference on FM and television transmission, that the radio waves would stop at the boundary of the quasi-optical horizon.
Memories are glowing embers from the past and spotlights into the future for those who can per into the future. perhaps this experiment with the channel conversion has much much bigger implications for the future than we suspect today. What was begun in this little hut might become a great technical achievement worthy of the relay station tower.
What was begun in 1953 in that hut on the Radspitze was fur a long time a great technical achievement that was constantly improved so that today we have satellite technology and who knows what the future will bring.




The Kronach TV repeater in 1956. The repeater still stands on the Radspitz today but today in 2001 it is only useed as a lookout tower.

Article from the Loewe Opta Courier 1 1956

Hans Stellmacher September 2001.