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  I2YOT Mimma and IW2BFP Ubaldo (Uba) made usual QSO, DX, awards and contests, but had
prevalently a good activity in A.T.V. (Amateur TeleVision) on 70 cm. till 1985.
The system in use was the same as for commercial TV,in accordance with the rules of C.C.I.R.:
so the receiver was a common television with a simple frequency converter. The transmitter
had to be homemade because at that time there was anything ready in commerce:video cameras
were the ones used for video entry phones.
 A received image picture, printed generally by a Polaroid photo camera, is enclosed to
the QSL card. 
 A very popular ATV transmitter was described by DJ4LB on VHF COMMUNICATIONS. Some other 
works by G6ADL (hybrid circuit), by G6AFF and by some Italian OM have been interesting too. 
 The signal needs amplifiers strictly in class A, so powers were low (about 1,5 W) and more
important was the antenna’s gain.
 After some months of tests IW2BFP and I2YOT published an article about A.T.V. system,
stimulating the A.T.V. national manager I2ORX. We thank him till now for his help.
 Actually our activity in A.T.V. is practically null because we don’t know anybody
operating on this mode at 1.2 GHz.

Picture in the top-left corner. Video GBC Mark XIV with a 1/2" Plumbicon tube.
Picture in the center. Videocamera Marelli with a 1" Vidicon tube.
Picture on the right. Video Marelli CT 21R with a 1" Plumbicon tube.
Recently a digital color Videocamera Philips has been added.
Picture at side. Field meter FPM 134 HIRSCHMANN. This instrument is useful not only for A.T.V. because the band IV begins at 425 Mhz and the band III at 137.
Calibration is done once a year.

We will never forget this contact.
The modulator is ready and Mimma and me make a local
transmission test. We put the antenna of the hand-transmitter
for 70 cm and we ear the voice of I2ORX “Mimma, I receive your
call”.
It’s difficult for him to believe how our conditions are and it’s
difficult for us to believe that the signal is real. We do agree for
another test with the videocamera after dinner. We connect
the videocamera Mark XIV and I2YOT sets for a close up.
We are waiting.
On 2 meters Giampaolo says “ Mimma do not move, please! OK.
Tomorrow you will have the pictures”.
You can see the pictures, the QSL and also the I2ORX’s QTH
with his TX-RX.

We had some other test pictures using the Commodore 64, when we were in Monza. A.T.V. will be for us the favourite activity till 1986, with a 15 elements beam and a linear amplifier.

When the private televisions were not so common, IW2BFP and I2YOT were transmitting this picture for transmission tests.

I began seriously my activity in A.T.V. when I read an article by I2ORX, Giampaolo and I2NFB, Franco: it was published on Radio Rivista n°1 in 1979 and described the construction of an ATV transmitter using DJ4LB’s circuits, that appeared on VHF Communications. I had dedicated my tyme before to antennas and receiver converters; then , with elementary circuits, I began to transmit grids and chessboards painted by Commodore 64 and then I realized also the Tx DJ4LB with a videocamera. I began to change some circuits in this project with some new ones, till the ATV transmitter was completely home made (IW2BFP TX). So I realized a very compact video transmitter that was using directly the frequency 434.250, instead of a subcarrier of 38,9 MHz. The construction proved to be sure and valid, but unfortunately, after some months, ATV transmissions in 70 cm. were forbidden in Italy. In some other countries, with any prohibition, the transmitter has been well accepted and most successful. The activity in 1.2 Ghz has been very poor both for realizations and for distances (only in the city of Milan). When I moved in Pizzoli, I stopped completely every ATV activity.

On the left a block diagram of the ATV transmitter BFP 70. On the right. The modulator, BFP 3, the one survived after
the demolition.

Electrical diagram of the ATV modulator BFP 3 ( negative amplitude modulation ) at 434.250 Mhz.

Some other parts survived to demolition. On the left. Interstadial coupling with helicoidal filters between mixer and driver in ATV TX by DJ4LB. In the center and on the right. Two cavity oscillators for some AM A.T.V. transmitters on 1,2 Ghz. The right cavity is exceptionally stable and has been long time the core of a FM transmitter.

A fortuit visit to an ATV Web site arouses in both I6YOT and IW6MKI the sleeping passion. We find every actual information on ATV and look for any possible SHF devices in our possession. Between those some 900 MHz resonators. I reduce the dimensions of one of them, controling each tenth of mm how much the frequency is increasing.
I calculate after some tests that a 0.75 mm reduction will be good. In the upper left picture you can see a Siemens original ceramic resonator and the oscillator circuit that I used in order to test the frequency. The frequency meter was an HP 5245 L with a plug-in unit 5254B. I prefere this counter because the tuneable cavity and the voltmeter permit to measure the harmonics too and relatives amplitudes. After a 0,72 mm reduction, I obtained the frequency of 1240 Mhz. On the right you can see a 1,2 Ghz output stage with some 85 watt power on FM phone. We believe to be active once again on ATV next spring. If our transmitter will be reliable, we will describe it on this page.

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LAST UPDATE 25/10/03 THANKs FOR TRASLATION IK6CAC

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