Modification of Drake 2880 Converter


               ======================================
                2.4GHz_2.7GHz  Converter User Manual
                Modification of Drake 2880 Converter
               ======================================


Note : This Millicom's Manual was translated from Japanese into
       English by JE9PEL / Mineo Wakita, 27 Feb 2001.
       The following photos were attached from HP of JN1GKZ.
       http://www.ne.jp/asahi/m-arai/gkz/sband/convmode.htm


This converter is usable in 2.4GHz_2.7GHz.  If we modify something
its inside when we want to use in 2.4GHz_2.5GHz, it will gain up.
There are the other way to use it in addition to 2.4GHz converter.
We will explain later about these usage.


1. Configuration (Sample measurement) Frequency : 2.4GHz_2.7GHz (If we modify something its inside when we want to use in 2.4GHz_2.5GHz, it will be gained up.) IF OUT frequency : 140MHz_400MHz LNB gain : 24 dB NF : 3 dB LO frequency : Local Oscillator 2.28GHz (standard) PLL formation (Fluctuating freq. : fo +/-30Hz) Power source : +12V_+24V 190mA (Supply from coax(signal+power) to IF OUT) Others : Waterproof case and connector, Metal tag to mast Note: In case of supplying power from the outside, modify in Drake. (Necessary) Put off one coil between F connector and power source. See photo5 in http://www.ne.jp/asahi/m-arai/gkz/sband/mod2e.htm (Necessary) Solder wire cable to a lead of diode. See photo6 in http://www.ne.jp/asahi/m-arai/gkz/sband/mod2e.htm 2. Circuit constitution (N_conn.) Matching RF Matching IF (F_conn.) RF IN ------ Coil --- AMP --- Coil --- BPF ----- AMP ----- IF OUT 2.4_2.7GHz 2.5GHz | *3 | 140_400MHz | | MIX | | Power Source Xtal ------ PLL --------- VCO 8.8984MHz (LO 2.28GHz) (Xtal*256) Inside of Drake. (See the above photo.) _____________________ | | | | RF __| RFAMP-BPF-MIX-IFAMP |__ IF VCO Vol. Freq. IN (__| | |__) OUT 0V 2.00GHz | =========== | ===== | 5V 2.26GHz | | | 10V 2.43GHz | Xtal---VCO--- | 12V 2.49GHz | 2.28GHz | 15V 2.53GHz |_____________________| 3. Characteristic of RF AMP, MIX, IF AMP (before modification) RF IN RF IN RF AMP RF AMP IF OUT IF OUT LNB freq. level OUT level gain freq. level gain - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2.3GHz -50dBm -42dBm + 8dB - - - 2.4GHz -50dBm -39dBm +11dB 120MHz -43dBm + 7dB 2.5GHz -50dBm -37dBm +13dB 220MHz -27dBm +23dB 2.6GHz -50dBm -37dBm +13dB 320MHz -26dBm +24dB 2.7GHz -50dBm -37dBm +13dB 420MHz -28dBm +22dB 2.8GHz -50dBm -37dBm +13dB - - - 3.0GHz -50dBm -38dBm +12dB - - - 3.5GHz -50dBm -39dBm +11dB - - - (LO freq. 2.28GHz) 4. Characteristic of LO OUTPUT level : +12dBm OUTPUT freq. : 2.28GHz (Xtal 8.8984MHz * 256 = 2277.9904MHz) (Frequency turn OK by Xtal change) Noise level : fo +/-40kHz / -45dB Spurious : 2fo -20dB, 3fo -40dB Fluctuating freq.: fo +/-30Hz Tuning freq. : -500kHz_+1MHz by trimmer 5. RF AMP modification to 2.4GHz Original RF AMP gain of 2.4GHz is 11dB, so we modify to gain up. (There is not necessarily to do this modification because it is only smaller 2dB as comprared with 2.5GHz_2.8GHz.) _FET IN ====== (_) === === ----cut |_| Cut a matching coil of RF AMP input |__| side. And solder 6mm enamell wire. Solder 6mm (0.1mm_0.2mm in diameter) enamell wire 6. IF AMP modification (Necessary) Modify to gain up this LNB for under 200MHz IF frequency of 2.4GHz. Note: See photo3 in http://www.ne.jp/asahi/m-arai/gkz/sband/mod1e.htm _____________________ @ Put off each condenser(2) | | and coil(2) situated on *. | 510 | | * * | Before modification: | 100 511 | IF OUT -43dBm | | | 512 |__ IF After modification: | * * |__) OUT gain up for 100_200MHz | | |_____________________| For example: IF OUT -28dBm on RF IN -50dBm Note: (Necessary) We must change Xtal from 8.8984MHz to 8.8125MHz, such as (2400MHz - 144MHz) / 256 = 8.8125MHz. See photo7 in http://www.ne.jp/asahi/m-arai/gkz/sband/mod31e.htm Then: Frequency : 2400.0MHz IF OUT frequency : 144.0MHz LNB gain : 27 dB NF : 3 dB LO frequency : Local Oscillator 2256MHz (standard) PLL formation (Fluctuating freq. : fo +/-50Hz) (N_conn.) Matching RF Matching IF (F_conn.) RF IN ------ Coil --- AMP --- Coil --- BPF ----- AMP ----- IF OUT 2.4GHz 2.4GHz | *3 | 144MHz | | MIX | | Power Source Xtal ------ PLL --------- VCO 8.8125MHz (LO 2.256GHz) (Xtal*256) 7. Other applications (1) LO 2.28GHz * 2(Doubler) = 4.56GHz, so apply LO 5.7GHz. _____________________ | | @ FET*2 and AMP*1, then 4.5GHz| *2 or *4 | +15dBm on 4.56GHz. OUT __| Circuit made |__ (__| | |__) FET*4, then 9.12GHz, | | | so apply LO 10GHz. | | | | LO ____| | | 2.28GHz | |_____________________| (2) Amp directly under antenna of 1.2GHz or 2.4GHz /-/-/-/-/ Antenna /-/-/-/-/ @ Even if it's rainy, that | is safe for a waterproof |-| Converter 1.2 or 2.4GHz case. And it's convenient | +------+ when we operate in the | +--------------| | open air. | Cable +------+ Receiver (3) Apply 5.7GHz Converter _____________________ | | @ If we use MGA86576(Co.HP) 5.7GHz| | and ERA3(mini circuit) as IN __| RFAMP--MIX--IFAMP |__ IF 5.7GHz AMP, it's put in (__| MGA | ERA-3 |__)OUT compactly as small size. | -86576 | | 1GHz | *2(Doubler) | @ MGA-86576 and ERA-3 are | PLL ___| | device of 50ohm input and | LO | output, so we can use in |_____________________| a strip line (same power source). (4) Apply 2.4GHz FM ATV Transmitter _____________________ @ If Xtal is changed to | | 9.47MHz, LO frequency 2.4GHz| 2.4GHz | turn 2424.32MHz, so we OUT __| 100mW Amp |__ can apply it to 2.4GHz. (__| | |__) And we can modulate VCO | |OUT 10mW | directly to TV. We must | | | amplify VCO output for | 2.28GHz | weak 10mW. | PLL LO ///// | |_____________________| VCO coil | ////////// Video modulation 512--512 | directly to VCO ----------> --103---Varicap


Back to Top
Back to Home Page