The path on the air today is very different from the training of the Soviet era. Training school at DOSAAF operating well. Interest groups, club stations actually not.
As a result, new staff into the ranks of amateur radio short wave and ultra-short wave pass self-study. Not rarely happens training in clubs and communities that have a need for radio communications. As an example - the tourists, motorists, hunters, etc. .. Mastering does not begin with the HF and VHF bands with. The reason for that - a wide range of portable public radio stations. At a cost of up to $ 50. for the new you can purchase dual-band VHF transceiver. Example Baofeng, Voxung, Puxing. The next step - the external antenna and a circular directional radiation.
When meeting with HF is an urgent need for an inexpensive and reliable transceiver. It is unfortunate that at the moment there is no cheap serial devices for HF communications accessible to beginners. Not being able to buy, there is always an opportunity to make their own equipment. The difficulty arises only in the configuration. Nevertheless, the circuitry could be laid in the stabilization modes for AC and DC, e.g. EP, and frequency stabilization based on piezoelectric (crystal stabilization).
Analyzing simple designs for self-assembly, it is obvious that the most simple telegraphy. Particularly attractive PIXIE or Micro-80. However, ignorance of the new ham telegraph makes these projects unattractive for all the simplicity and adaptability.
To work in a single-sideband modulation of voice noteworthy design Amator-EMF, BITX, Klopik itp But for phone power is needed, which is not immediately able to provide, which is why the phone is tedious work. Good compromise - simple transceivers for digital communications. Interesting design NIKI-80 and WARBER. However, the first mode which provides the two sidebands, which leads to excessive noise during operation. The second road on the packaging and in the complex adjustment. We offer a simple, reliable, single-HF transceiver designed for digital communication procedures and modes (DIGI MODES). When building from serviceable components, the transceiver does not need to be tuned and adjusted. The cost of the components is the equivalent of three (3) dollars. USA.
The main characteristics of the transceiver:
· Receiver Sensitivity better than 1 mV.
· Bandwidth (operating band): 3579.5-3581kGts.
· Transmit Power: 500mW.
· Power supply: 12V max 100mA max.
· Mode: psk, rrty, hell, mt, ...
Figure 1 - Connect the transceiver to a PC.
Figure 2 - Block diagram of the transceiver.
Figure 3 - Circuit diagram of the transceiver.
Figure 4 - Circuit boards weak signal of the transceiver.
Figure 5 - View transceiver assembled PCB.
The list of items:
C4,C6,C9,C11,C14,C16 = 6 x 33
C1 = 1 x 100
C13,C15 = 2 x 240
C2 = 1 x 680
C5,C10 = 2 x 0,015
C18,C19,C20,C21,C22 = 5 x 0,1
C3,C7,C8,C12 = 4 x 0,22
C17 = 1 x 47,0 x 16V
DA1 = 1 x LA1185
L1,L5 = 2 x 22µH
L2,L3,L4 = 3 x 100µH
La1 = 1 x 6.3v 20ma
R1,R2,R3 = 3 x 1k
R4 = 1 x 1k5
R5,R6 = 2 x 4k7
VR1 = 1 x LM7805
VT1 = 1 x 2sk241
VT2 = 1 x 2N7000
Z1,Z2,Z3,Z4,Z5 = 5 x 3,579 MHz