| Article Index |
|---|
| ATS 1 20m SSB CW Transceiver Construction: An Introduction |
| VFO and Band Operation |
| Notes - Before You Begin |
| Assembling the PCB |
| All Pages |
Page 1 of 4
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This construction article describes a single band all solid state SSB-CW Transceiver. The complete transceiver is assembled on a single side Glass Epoxy PCB measuring 25.5 c.m. X 16.5 c.m.(10" X 6.5"). The intended output power is around 15 watts but many HAMS have managed to get around 30 watts RF output on 20 meter band.
All electronic components used in ATS-1 are available in Indian market.
Several prototypes with some variation here and there were developed and one of them is described in this article. The original set of PCB's for this version were procured from Amateur Radio Association Delhi, and PCB's are now available with VU3CAV (OM Rajani Mohan) who has dedicated this project of ATS 1 home brew in memory of his fundamental, SK OM VU2MMP. VU3AKW (OM Ashok) has been instrumental in getting the required hardware purchased from various stores in Chandni Chowk in New Delhi - and no amounts of words can describe the efforts put together by OM Rajani and OM Ashok to make this project a success. On the construction front VU2ASB OM Ashok - is leading the front with meticulous planning and construction(check download section for his inputs), with assistance from OM Rakesh VU2RAK - who has matched down the circuit and PCB print and published his finding in the public forum on this site. Back to Construction of ATS 1.
All electronic components used in ATS-1 are available in Indian market.
Several prototypes with some variation here and there were developed and one of them is described in this article. The original set of PCB's for this version were procured from Amateur Radio Association Delhi, and PCB's are now available with VU3CAV (OM Rajani Mohan) who has dedicated this project of ATS 1 home brew in memory of his fundamental, SK OM VU2MMP. VU3AKW (OM Ashok) has been instrumental in getting the required hardware purchased from various stores in Chandni Chowk in New Delhi - and no amounts of words can describe the efforts put together by OM Rajani and OM Ashok to make this project a success. On the construction front VU2ASB OM Ashok - is leading the front with meticulous planning and construction(check download section for his inputs), with assistance from OM Rakesh VU2RAK - who has matched down the circuit and PCB print and published his finding in the public forum on this site. Back to Construction of ATS 1.
The PCB contains all the sections of the transceiver : RX mixer, 9 MHz crystal filter, post filter amplifier, IF amplifier, product detector, noise limiter, AGC, audio pre and power amplifier, variable frequency oscillator (VFO), Beat Frequency Oscillator (BFO), Mic amplifier, balanced modulator, Transmit mixer, driver and power MOSFET RF power amplifier, output power sampler and complete power supply.
Since the complete TRX is on a single PCB, it may look complicated at first sight but everything being on the same PCB makes it more compact and easy to assemble. On carefully checking the PCB you will find space for more number of components and more holes drilled than required. This is because the PCB is designed to accommodate different sizes of components with the idea "if this is not available you can use that".
The only thing unique in the circuit is the use of CA7611 (an IC primarily designed for the video section of colour TV receiver), as the receiver IF amplifier, product detector, noise blanker, and audio pre amplifier. Except the audio derived AGC and the use of 761 1, rest of the circuit blocks have been taken for various HAM publications and application notes.
The lack of switching of VFO and BFO signals during TX RX change over in ATS-1 is not, what an electronic engineer would recommend, but has been used nevertheless for simplifying and minimizing the number of components.
The ATS-1 is a single conversion transceiver with intermediate frequency of 9 MHz. A 9 MHz crystal filter manufactured by Bharat Electronics Limited (BEL) is used. The carrier generating crystals are also from BEL. Crystal filter and Crystals used in BFO are available as part of the kit - that has been made available by VU3CAV.
Since the complete TRX is on a single PCB, it may look complicated at first sight but everything being on the same PCB makes it more compact and easy to assemble. On carefully checking the PCB you will find space for more number of components and more holes drilled than required. This is because the PCB is designed to accommodate different sizes of components with the idea "if this is not available you can use that".
The only thing unique in the circuit is the use of CA7611 (an IC primarily designed for the video section of colour TV receiver), as the receiver IF amplifier, product detector, noise blanker, and audio pre amplifier. Except the audio derived AGC and the use of 761 1, rest of the circuit blocks have been taken for various HAM publications and application notes.
The lack of switching of VFO and BFO signals during TX RX change over in ATS-1 is not, what an electronic engineer would recommend, but has been used nevertheless for simplifying and minimizing the number of components.
The ATS-1 is a single conversion transceiver with intermediate frequency of 9 MHz. A 9 MHz crystal filter manufactured by Bharat Electronics Limited (BEL) is used. The carrier generating crystals are also from BEL. Crystal filter and Crystals used in BFO are available as part of the kit - that has been made available by VU3CAV.
