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On the occasion of HAMFEST 2012 we have made a 20 meter receiver, with 3 slight changes in the GR 40 receiver. The range of it is 200 KHz (14.059MHz-14.259MHz).
This year the All India HAMFEST 2012 is being held on the 15th December 2012 at Chennai,TN. This 20 Meter receiver was made for receiving foreign stations.
The schematic of 20 meter receiver is same as the GR 40 receiver except one trimmer capacitor. The capacitor C43 is replaced by Teflon coil. (For GR40 Rx. related documents please Click Here)
We have used 18.432MHz crystal (instead of 12MHz crystal which is used in GR 40). The I.F range is from 18.426MHz to 18.430MHz, for this the two resistor (R23 & R24) have changed to 22 Ω by which the range of I.F is 3KHz. To change the BFO frequency we have used a Teflon coil in place of Trimmer C43. The coil dimensions are 7 mm long *10 mm diameter with 13 turn, the gauge of a wire is 22 SWG. The two legs have to be mounted such that one is to be grounded and another is to live.
In RF the inductors L1 and L2 are changed to 15 turn on 13mm long *10 mm diameter coil , the gauge of a wire is 26 SWG. The capacitors C5,C7,C11.C6 are changed to 47pf and C12,C13 to 180pf. The range of RF is from 14.059MHz to 14.259MHz, (which is obtained as RF=IF-VFO)
The receiver is working beautifully. It is tested on air and received the very clear and strong signals from VU2AU,VU2OO (Madhya Pradesh), VU3RAZ (Nagpur) and VU2KNN Rajan (HYD).
On the occasion of HAMFEST 2012 we have made a 20 meter receiver, with 3 slight changes in the GR 40 receiver. The range of it is 200 KHz (14.059MHz-14.259MHz).
This year the All India HAMFEST 2012 is being held on the 15th December 2012 at Chennai,TN. This 20 Meter receiver was made for receiving foreign stations.
The schematic of 20 meter receiver is same as the GR 40 receiver except one trimmer capacitor. The capacitor C43 is replaced by Teflon coil. (For GR40 Rx. related documents please Click Here)
We have used 18.432MHz crystal (instead of 12MHz crystal which is used in GR 40). The I.F range is from 18.426MHz to 18.430MHz, for this the two resistor (R23 & R24) have changed to 22 Ω by which the range of I.F is 3KHz. To change the BFO frequency we have used a Teflon coil in place of Trimmer C43. The coil dimensions are 7 mm long *10 mm diameter with 13 turn, the gauge of a wire is 22 SWG. The two legs have to be mounted such that one is to be grounded and another is to live.
In RF the inductors L1 and L2 are changed to 15 turn on 13mm long *10 mm diameter coil , the gauge of a wire is 26 SWG. The capacitors C5,C7,C11.C6 are changed to 47pf and C12,C13 to 180pf. The range of RF is from 14.059MHz to 14.259MHz, (which is obtained as RF=IF-VFO)
The receiver is working beautifully. It is tested on air and received the very clear and strong signals from VU2AU,VU2OO (Madhya Pradesh), VU3RAZ (Nagpur) and VU2KNN Rajan (HYD).
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