RTX 1.3 GHz

TX exciter: two versions were created. The first one for which the electrical diagram is provided was based on the 10 MHz quartz oscillator with a whole series of multipliers to reach 1280 MHz: all this entailed a very critical calibration of the circuits and also a certain instability. Problems solved with the second version where the PLL system is used. The only problem is obtaining the right coupling between the L1 L2 coils at the input of the U664. These coils are made in a 'U' shape with 1 mm wire and a height of approximately 10 mm. The double-sided circuit is essential with the upper part as the ground plane to appropriately shield the various sections. A few words about the preamplifier with two GasFet MGF1302: mounted in the air inside a metal container. Below is the layout of the components and relative measurements. .

Project .. Transceiver 1 . 3 GHz
Wideband transceiver for packet links on the 23 cm range. To increase the normal speed of 1200 bps, in addition to the appropriate modem, it is no longer possible to use normal commercial transceivers due to their limited bandwidth: therefore a specially designed device using easily procured components. As mentioned, it is divided into 5 separate modules plus an antenna preamplifier (optional) made up of antenna switch, exciter transmitter, final transmitter, RF part receiver, IF part receiver.
	Antenna switch: Uses BA379 switching PIN diodes. The part with the BD136 is mounted vertically on a small separate board: you can see the red and green LEDs to signal TX or RX. RF final: the final used is the BFQ68 with an output of approximately 1.5 - 2 Watts: naturally it must be dissipated with a sheet metal welded under the PCB which also guarantees ground contact. As can be seen, for the final calibration it is necessary to optimize the microstrips by adding sheet metal scraps.
		TX exciter: two versions were created. The first one for which the electrical diagram is provided was based on the 10 MHz quartz oscillator with a whole series of multipliers to reach 1280 MHz: all this entailed a very critical calibration of the circuits and also a certain instability. Problems solved with the second version where the PLL system is used. The only problem is obtaining the right coupling between the L1 L2 coils at the input of the U664. These coils are made in a 'U' shape with 1 mm wire and a height of approximately 10 mm. The double-sided circuit is essential with the upper part as the ground plane to appropriately shield the various sections. A few words about the preamplifier with two GasFet MGF1302: mounted in the air inside a metal container. Below is the layout of the components and relative measurements. .

RF part receiver and IF part receiver: input signal at 1280 MHz and is converted to 65 MHz to enter the IF receiver base. Here too it is necessary to optimize the microstrips with appropriate sheet metal cuttings. The electrical diagram provides the essential data for the creation of MFs and coils.. Further documentation is available upon request ..
Page no. 1: includes GasFet preamplifier, antenna switching, RF receiver and IF receiver. Page no. 2: includes TX exciter I and II versions, TX final .