Designing 2 Elements 20 m. Band Cubical Quad (Horizontal Polarization) Using MMANA-GAL Free Software

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Proper RF Power Measurement Technique for RF Amplifier Design Purpose

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Designing CB Mobile Antenna Using MMANA-GAL Free Software

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Designing 28 MHz 2 Elements Horizontal Yagi Using MMANA-GAL Free Software

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Laporan Kerja Praktek Moch. Nasrull Fadillah 1211707043 Teknik Elektro Universitas Islam Negeri Sunan Gunung Djati (UIN-SGD) Bandung

Ini linknya: https://drive.google.com/file/d/0B6tt_2iG0k9uMTRHRHFORl8zeVE/view?usp=sharing

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Laporan Kerja Praktek Cecep Abdul Muhaemin 1211707013 Teknik Elektro Universitas Islam Negeri Sunan Gunung Djati (UIN-SGD) Bandung

Ini linknya: https://drive.google.com/file/d/0B6tt_2iG0k9uWmRKSEJMbmp3UDA/view?usp=sharing

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Seminar & Workshop Perancangan Antena, Jur. Teknik Elektro, Universitas Islam Negeri Sunan Gunung Djati Bandung

Untuk mengunduh yang dalam bentuk .pptx:
https://drive.google.com/file/d/0B6tt_2iG0k9ueC1icEF2Q3Y2SUU/view?usp=sharing

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Amateur Radio Narrow Band Digital Communication Using BPSK31

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Perancangan Antena Dipol Tegak Berfrekuensi Tengah 141,5 MHz

Kerja Praktek Moch. Nasrull Fadillah 1211707043 Teknik Elektro, Fakultas Sains dan Teknologi, Universitas Islam Negeri Sunan Gunung Djati (UIN SGD):



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Perancangan Antena Dipol Tegak Berfrekuensi Tengah 149 MHz

Kerja Praktek Cecep Abdul Muhaemin 1211707013 Teknik Elektro, Fakultas Sains dan Teknologi, Universitas Islam Negeri Sunan Gunung Djati (UIN SGD) Bandung:



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Smith Chart and Its Practical Applications

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High Gain Wide Band 28 MHz 3 Elements Horizontal Yagi Design

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My Small Power VHF FM Transmitter Design

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Designing 14 & 21 MHz Single-Fed Double Inverted Vs Using MMANA-GAL Free Software

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How to Determine Coaxial Cable Length Correctly for Your Antenna?

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Designing 7 MHz Mobile Antenna Using MMANA-GAL Free Software

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Designing 28 MHz 3 Elements Wire Yagi Using MMANA-GAL Free Software

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Designing 28 MHz 1 Element Delta Loop Antenna

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Designing High Stability Variable Frequency Oscillator Using Series Tuned Clapp

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Communication Microphone for High Power Transmitter

This is my design, and suitable for most of Amateur Radio & whatever transmitters which have power up to 100W PEP. The keys of this design compared to my previous designs are utilization of 2 RF filters located after condenser mic and voltage supply from power supply, and good ground connection connected from ground section of this mic preamp to ground installation at your soil. These are ways to suppress RF feedbacks from entering processing in transistor (2SC828).

This design has been tested using 100W transceiver with antenna SWR 1-1.5, and still produced clear voice. Mic used is cheap 2 leads condenser mic. Under is photo of this design after placed at PCB:

If you like to design microphone, especially mic that is used with high power transmitter, You have to be able to suppress RF that comes back to mic from antenna. One simple thing is to make your antenna SWR as small as possible (try SWR 1.0). With SWR 1.0, all of power generated by final amplifier would be dissipated at antenna, with higher SWR, there would be portion of power reflected back from antenna to final amplifier causes RF feedbacks on mic system. If your SWR already 1.0, but still You are having RF feedbacks, then You should utilize RF filter.

At this design, RF filter composed of one 27mH inductor (looks like black capacitor at photo), and two 1500pF ceramic capacitors. For higher transmitter power, You could experiment with more suppressing RF filter, logically: higher inductor value, and higher capacitors value. Utilization of grounded metal box, logically would suppress RF more. Try as far as You could until RF is not processed at mic circuit.

Components should be placed as close as possible, and cables should be as short as possible. These would reduce RF feedbacks. This is because long cables function as antennas.

+12-13.8 VDC could be taken directly from ordinary power supply.

68n & 47n are coupling capacitors. Their main function is to keep DC around transistor, while AC could travel from outside to transistor, and from transistor to outside. This unique capacitor characteristic could be used to determine audio tone of this mic system. Lower capacitor value tends to produce higher audio frequency (treble), and vice versa. Basic criteria when You are designing audio system for communication is Signal to Noise Ratio (SNR). Higher SNR, better, of course with clear signal without distortion. You could try to investigate Noise (QRM & QRN) on working frequency, and try to experiment with various audio tones, to try to make highest SNR, eg. if noise figure is bass, and Your audio tone is bass as well, so SNR would be low, so You have to make Your audio tone treble, so SNR would be higher, and Your audio would be more readable.

68n & 47n are green mylar capacitors.

To reduce fatigue, this mic could be designed as desk microphone.

Have a nice try and Good DX.