Turorial Penggunaan SWR & Power Meter Maldol HS 260S Turorial Penggunaan SWR & Power Meter Maldol HS 260S

Bagi yang hobi pemancar tentunya tidak terlepas dari alat yang dinamakan SWR atau VSWR(Voltage Standing Wave Ratio). VSWR adalah perbandingan antara tegangan maksimum dan minimum pada suatu gelombang berdiri akibat adanya pantulan gelombang yang disebabkan tidak matching-nya impedansi input antena dengan saluran feeder. Alat VSWR biasanya digabung dengan alat POWER METER yang berfungsi untuk mengukur kekuatan daya pancar pemancar yang diukur dengan Watt. Salah satu alat VSWR ini yang beredar di pasaran salah satunya adalah SWR & Power Meter Maldol HS 260S. SWR type ini banyak digunakan oleh para penggemar pesawat pemancar karena selain harganya yang murah kualitasnyapun bisa diandalkan. Untuk mengetahui cara menggunakan alat SWR ini saya mengutip penjelasan teman saya Kang Joe Ponorogo beliau adalah penggemar elektronika khususnya dalam pembuatan pesawat pemancar,

Cara Penggunannya sebagai berikut:
1. Untuk mengetahui daya pemancar dibawah 12 Watt :
• Pasang Dummyload sebagai pengganti antenna pada konektor output SWR
• Posisikan saklar pada posisi Pwr dan skala pada 12W
• Nyalakan pemancar dan lihat nilai yang ditunjukkan oleh jarum pada skala power meter.
2. Untuk mengetahui daya pemancar diatas 12 watt dan dibawah 240 watt :
• Pasang Dummyload sebagai pengganti antenna pada konektor output SWR
• Posisikan saklar pada posisi Pwr dan skala pada 240W
• Nyalakan pemancar dan lihat nilai yang ditunjukkan oleh jarum pada skala power meter.
3. Untuk mengetahui nilai SWR (Impedansi) pada pemancar :
• Pasang Dummyload sebagai pengganti antenna pada konektor output SWR.
• Posisikan saklar pada posisi SWR
• Saklar skala 12w/240w tidak berpengaruh
• Putar potensio pada posisi minimal
• Nyalakan pemancar
• Putar potensio sampai jarum pada skala power meter menunjukkan angka maksimal 12w/240w
• Lihat jarum SWR
• Itulah nilai SWR yang didapat
4. Untuk mengetahui nilai SWR (Impedansi) pada antenna (Setting antenna) :
• Pasang antenna pada konektor output SWR menggunakan kabel coaxial dengan impedansi yang sesuai (biasanya 50 Ohm)
• Posisikan saklar pada posisi SWR
• Saklar skala 12w/240w tidak berpengaruh
• Putar potensio pada posisi minimal
• Nyalakan pemancar
• Putar potensio sampai jarum pada skala power meter menunjukkan angka maksimal 12w/240w
• Lihat jarum SWR
• Itulah nilai SWR yang didapat
NB :
• Tune pemancar sampai mendapatkan power terbesar dengan nilai swr terendah (Impedansi sesuai dengan beban/dummyload)
• Tune antenna sampai mendapatkan nilai SWR terendah. Semakin rendah/kecil nilai swr semakin bagus.
• Untuk pengerjaan pemancar FM atau HT impedansi yang digunakan biasanya 50 Ohm
• Dummyload bisa dibuat dengan memparalel Resistor 1 Kilo Ohm 2 Watt sebanyak 20 biji (hasil akhir parallel = 50 Ohm)

Untuk membeli alat SWR ini anda bisa mendapatkannya di Toko Elektronika atau anda bisa menghubungi Kang Joe Ponorogo (Yuhana Agung Satria) di alamat Facebook nya. Beliau juga menjual SWR type ini baik yang masih asli dari pabrik maupun yang sudah dimodifikasi dan dikalibrasi, jadi anda tinggal menggunakannya.

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Rangkaian Power Amplifier Pemancar FM 4-20 Watt Rangkaian Power Amplifier Pemancar FM 4-20 Watt

Rangkaian Power Amplifier Pemancar FM ini sangat sederhana, namun kualitasnya cukup memuaskan.

A very simple fm power amplifier which can deliver 4W rf power with 12V power supply and BLY87A or KT920A and 20W with BLY89A or KT925B.
If you use BLY87A or KT920A the input power must be 0.5W and 4W if you use BLY89A or KT925B. This fm power amplifier is designed to work on 50 Ω antennas and a maximum power supply of 14V and in 88 108 MHz band.
Use only metallic trimmers, a good heatsink for the transistor and ceramic capacitors and keep the pins very short.
FM power amplifier circuit components:
C1 = C8 = 10-40pF + 22pF in parallel ||
C2 = 10-70pF + 120pF ||
C3 = 2.2nF
C4 = 33nF
C5 = 4 x 180pF
C6 = 1nF
C7 = 2.2nF
C9 = 10-70pF + 47pF ||
R1 = 380Ω
R2 = 47Ω
R3 = 5.6 Ω
L1 = 3 turns / 0.8mm / 6mm / legth = 8mm
L2 = 6turns / 0.5mm /over R2
L3 = 5 t / 0.6mm / 6mm
L4 = 4 t / 1.2mm / 8mm
T = 4W with BLY87A, KT920A
T = 20W with BLY89A, KT925B

FM amplifier circuit schematic

 Source: http://electroschematics.com

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2 Watt FM Transmitter 2 Watt FM Transmitter

The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz. Audio picked up and amplified by the electret microphone is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates the resonant frequency of the tank circuit (L1 coil and the trimcap) by varying the junction capacitance of the transistor. Junction capacitance is a function of the potential difference applied to the base of the transistor T2. The tank circuit is connected in a Hartley oscillator circuit.

Components List

R1=220K R2=4.7K R3,R4=10K R5=100ohm

C1,C2=4.7uF Electrolytic C3,C4=1nF C5=2-15pF C6=3.3pF

Q1=BC547C Q2=BD135 P1=25K MIC=Electret Condenser Type

P1 act as condenser microphone volume level. For FM, coil will be small. Use thin gauge enamel magnet wire. the diameter of coil will be a couple mm: use ink tube from pen to form, and try 8-12 turns. Small inductance coils make for much guess work.

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Stereo FM Transmitter Based BH1417 Chips Stereo FM Transmitter Based BH1417 Chips

This electronic circuit is a latest BH1417 FM Transmitter design from RHOM that includes a lot of features in one small package. It comes with pre-emphasis, limiter so that the music can be transmitted at the same audio level, stereo encoder for stereo transmission, low pass filter that blocks any audio signals above 15KHz to prevent any RF interference, PLL circuit that provides rock solid frequency transmission (no more frequency drift), FM oscillator and RF output buffer.

There are 14 possible transmission frequencies with 200KHz increments that users can select with a 4-DIP switch. Lower band frequencies start from 88.7 up to 89.9 MHz, and upper band frequencies start from 107.7 up to 108.9 MHz.


BH1417 can be supplied with 4 - 6 voltage and consumes only around 30mA, providing 20mW output RF power. BH1417 provides 40dB channel separation which is pretty good, although older BA1404 FM Transmitter chip provides slightly better 45dB channel separation.


BH1417 is only available in SOP22 IC case so this may be an inconvenience for some folks. On the other hand, because the chip is smaller than regular DIP-based ICs it is possible to fit the entire transmitter on a small PCB.

The bad news is that BH1417 requires 7.6MHz crystal oscillator, which is very hard to find. The good news is that you can use 7.68 MHz crystal instead, which is easier to find. In fact our BH1417 transmitter prototype (schematic shown above) uses 7.68 MHz crystal. This has absolutely no effect on stereo encoding process, we have tested it and stereo sound is crystal clear. The transmitted frequency on the other hand will be shifted up by exactly 1MHz (example: 88.1 MHz to 89.1 MHz) which is perfectly fine. The frequencies that are used in this project have been adjusted by 1MHz already so no additional conversion is necessary.

BH1417 chip may also be used a stand alone stereo encoder. The advantage of that is that you have full freedom of using a transmitter & amplifier of your choice. You will still have a pre-emphasis, limiter,stereo encoder and low pass filter in one small package because very few external components are required for these blocks. PIN 5 is MPX output that can be directly connected to an external FM transmitter through a 10uF cap.


Parts List:
1x BH1417 - Stereo PLL Transmitter IC (Case SOP22) (datasheet)
1x 7.68 MHz Crystal
1x MPSA13 - NPN Darlington Transistor
1x 2.5 Turns Variable Coil
1x MV2109 - Varicap Diode
1x 4-DIP Switch
ANT - 30 cm of copper wire

1x 22K Resistor
7x 10K Resistor
1x 5.1K Resistor
2x 3.3K Resistor
1x 100 Ohm Resistor 1x 100uF Capacitor
3x 10uF Capacitor
2x 1uF Capacitor

1x 47nF Capacitor
3x 2.2nF Capacitor
1x 1nF Capacitor
1x 330pF Capacitor
2x 150pF Capacitor
1x 33pF Capacitor
2x 27pF Capacitor
1x 22pF Capacitor
2x 10pF Capacitor

Specifications:
Supply Voltage: 4 - 6V
Transmission Frequency: 87.7 - 88.9MHz, 106.7 - 107.9MHz (200kHz steps)
Output RF Power: 20mW
Audio Frequency: 20 - 15KHz
Separation: 40dB
Power Consumption: 30mA

Frequency Selection / Calibration
Frequency selection is very straight forward. Simply select transmission frequency at which you would like to transmit, set the combination for 4-DIP switch and BH1417 will immediately tune to that frequency. If you can't hear the transmitted audio signal on your FM receiver then re-adjust 2.5 turn variable coil until you can hear the signal. If you have a laboratory power supply you may try to vary the voltage supply from 4 to 6V. While doing that BH1417 will automatically vary the voltage for MV2109 varicap diode making sure that there's no frequency drift.

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FM Transmitter (Pemancar FM) FM Transmitter (Pemancar FM)

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