Hola,
muchas gracias Jose por compartir tu experiencia y conocimiento, esto se pone interesante (y más dÃficil para decidirse), he estado revisando, los resultados de las medidas de algunos de los circuitos (en Rx) y parece algo mejor (ver extracto más abajo) el DR2G (más nuevo, en SMD y con mejoras introducidas por YU1LM ), con respecto al DR3X (ya probado por Jose, más sencillo y con garantÃas) . Con caracterÃsticas similares, en recepción, están el AVALA-01 y el ADTRX-2 (que también permiten Tx), pero, son más complicados (si sólo se quiere Rx, de momento), aunque con componentes discretos y con posibilidad de control adicional (puerto serie). Todos se alimentan a 12 V, justificado en el caso de los transmisores, pero, no necesario para Rx.
Hay otro diseño italo-germano, el PM-SDR (
http://www.iw3aut.altervista.org ), con caracterÃsticas (Rango de recepción, MDS, SFDR, Sens., IMD o IP3, ..), en recepción, similares al DR2G, pero, más completo, se alimenta del puerto USB (como los SoftRock) a 5V, tiene posibilidad de control por puerto USB (lleva PIC), sintonÃa contÃnua, es compatible con el WinRAD y con el WinRAD-HD (
http://freenet-homepage.de/winradhd/ ), se le puede poner un display LCD, etapa de transmisión y otras ampliaciones. Con respecto al AVALA y ADTRX-2, quedarÃa más compacto y con menos componentes. Venden un kit, display, caja y varias ampliaciones, pero, claramente es más caro (si se compra ahÃ). Parece que toda la información está disponible, incluyendo el programa del PIC.
Una combinación de ambos, podrÃa ser lo mejor, etapas de RF de YU1LM y control USB e interfaces del PM-SDR, pero, calculo que el coste, estarÃa entre los 100 y los 300 euros (dependiendo como se quiere de completo, con Tx, caja, display, otros complementos, ..).
Por cierto, he encontrado información detallada (con fotos) para el prototipaje de RF (incluyendo método "Manhattan") y más información sobre el "Softrock Lite V 6.2 Receiver Kit" en :
http://www.cliftonlaboratories.com/Prototyping.htm El extracto de los resultados, con pros y contras, y ajustes es:
Measuring results which I made with HF S/H SDR receiver DR2G 1.Receiving range is going from 30 kHz to 70(100) MHz.
2.IIP3 34-37dBm and it depends from setting and used programs.
3.MDS -120-122dBm also with 24 bit external USB SB card Audigy NX2
4.Image rejection is going from 35 -65 dB
5.DR2G sensitivity 0.3 - 0.6 uV for 10 dB S/N ratio, max S/N ratio I measured was 75 dB.
6.SFDR (Spurious free dynamic range) is 95-98 dB, this results are with signals spaced 5 kHz and more.
Some excellent performances aren’t without other side: 1.First and very big disadvantage is 4 or 2 times higher LO
2.Image rejection is changing through receiving bands and results are done for frequencies 12 kHz from central frequency
DR2G process adjustments are simple and done in two steps: 1.With 500OHms potentiometer adjust with DMM (digital multi meter) that resistance is 100 Ohms.
2.Second step is to with 500OHMs potentiometer in SDR software adjust max image rejection best frequency is about 12-30 kHz from 0 Hz. This depend from SB sampling rate
Measuring results which I made with HF S/H SDR receiver DR3X 1. Receiving range from 30 kHz to 35 MHz (with Q unit oscillator it is limited to the 30 MHz). With one XTAL 56.1 MHz it is possible to receive +/- 20 kHz around next frequencies 14.025 MHz, 7.0125 MHz and 3.507 MHz Bands are harmonically related. Max receiving frequency is achiving with external LO and Vcc=+6 V for digital ICs.
2. IIP3 27-29 dBm and it depends from setting and used programs (all with 16 bit sound cards).
3. MDS -102-105 dBm also with 16 bit SB card Realtek AC97
4. Image rejection is possible adjust to 35-60 dB 12 kHz from center frequency.
5. Sensitivity 3-5 uV for 10 dB S/N ratio, max S/N ratio I measured was 70 dB. This sensitivity is more than enough for frequency near to 20 MHz with adequate antenna system, for higher frequency it is recommend increasing AF gain (10 Kohms increase to max 100 Kohms R4,R29,R30 and R15) or putting some RF preamplifier in front of DR3X to lower F (noise figure) of receiver.
6. SFDR (Spurious free dynamic range) is 86-92 dB, this results are with signals spaced 5 kHz and more. Results are not changing very much if we spaced two signals to classical 20 kHz or more.
Some excellent performances with 3-5 IC are not without other side: 1. First and very big disadvantage is 4 times higher LO
2. Image rejection is changing through receiving bands and results are done for frequencies 12 kHz from central frequency
3. Harmonically bands are not always good choice. For example if we are using very frequent computer quarz 14.312 MHz we can receive +/- 20 kHz around 3.578 MHz,
1.789 MHz and 894.5 kHz middle frequency only touch beginning 160 m band and last one is out of any amateur bands.
4. For external LO it is necessary input level around 1 Vp-p min for safe operation (for lower LO drive operations are not sure especially for higher LO frequencies)!!!Simple test that 74HC4053 is working is to measure with DMM(dugital multimeter) Vcc/2 or 2.5 V +/-0.5 V at control pins 9 or 10. If it is not true we have a problem with input LO level or input ICs 74AC74 or 74AC02.
DR3X adjustments are simple and done in two steps: 1. Adjust with universal instruments DMM (digital multimeter) that is resistance in feedback potentiometer 5k +8K2 = 10 K.
2. Find some strong signal in the air 12 kHz away from zero or put signal from signal generator to the input of DR3X and with 5 kOhm potentiometer adjust min unwanted image signal in some SDR program. Additional image rejection adjusts in SDR programs if this possibility exist function such as skew in Alberto I2PHD programs.
Measuring results which I made with HF S/H SDR transceiver AVALA-01 (receiving results are the same for ADTRX-2 except that it hasn’t RF preamplifier) are:
1. Receiving range is going from 30 kHz to 35 MHz for DIL ICs version .With built in last
modern technology like 74LVC74 and 74LVC4066 and external LO to 52 MHz.
2. IIP3 32-35dBm and it depends from setting and used programs. I changed RX amplification
distribution. For first stage I increased gain to the 26 dB and decrease gain to 20 dB for the
second stage (all measurements done with 24 bit sound card).
3. MDS -116 to -122dBm also with 24 bit external USB SB card Audigy NX2 with RF
preamplifier on -132 to -134 dBm.
4. Image rejection is from 35 -65 dB with hardware realization only
5. Sensitivity 0.15-0.2uV for 10 dB S/N ratio, max S/N ratio I measured was 72dB.
6. SFDR (Spurious free dynamic range) is 93-94 dB, this results are with signals spaced 5 kHz
and more. Results are not changing very much if we spaced two signals to classical 20 kHz
or more (with new modern SMT ICs 74LVC4066 SFRD is 95- 97dB).
7. 1 dB compression point is + 5 dBm!!!
8. (Tx) Pout between 3-5W (2W 50MHz) with single FET amplifier .for ADTRX2 output power is
+10 dBm (I made one QSO with this power with LY station HI!)
9. Carrier suppression is -60 dBc(1.8 MHz),-56 dBc(3.5 MHz),-52dBc(7MHz),-48dBc(14MHz)
and -36dBc(28MHz) all results were achieved without built in components for additional
carrier suppression or software help.
10. Image rejection -55 dBc at 1.8 MHz to -40dBc at 28 MHz.
Some excellent performances aren’t without other side:1. First and very big disadvantage is 4 times higher LO. For 52 MHz maximum input frequency
LO frequency is 208 MHz.
2. Image rejection is changing through receiving bands and results are done for frequencies 12
kHz from central receiving frequency. There is also degradation in image rejection as
frequencies are increasing.
For external LO it is necessary input level to be around 1 Vp-p min for safe operation (for lower LO
drive operations are not sure especially for higher LO frequencies)!!!Simple test for
74HC4066(74LVC4066) correct operation is when we measure with DMM (digital multi meter) Vcc/2
or 2.5 V +/-0.5 V at control pins 12, 13 and 5, 6 If it isn’t true we have a problem with input LO level or
input ICs 74AC74 or 74HC4066 (74LVC4066).
AVALA-01 and ADTRX2 adjustments are simple and done in few steps:1. RX- Adjust with universal instruments DMM (digital multi meter) that is resistance in feedback RX
OP AMP NE5532 potentiometer 56 +100 = 150 Ohms
2. RX-.Find some strong signal in the air 12 kHz away from zero or connect signal from signal generator
to the input of DR2A++ and with 100(500)Ohm potentiometer adjust the minimum unwanted image
signal in some SDR program. Additional image rejection adjusts in SDR programs if this possibility
exists function such as skew in Alberto I2PHD programs.
3, 4, sección TX (../..)
PMSDR 2.1 FEATURES (NEWS)- continuously tuning the entire HF-spectrum (standard tuning range: 0,1 - 55 Mhz)
- First test results: (Test Setup :Signal Generator HP8640B , Soundcard Creative Xtreme 24bit , Software WinRad 1.32)
sensivity-MDS (with inserted preselection filter ), (2400 Hz bandwidth) with (S+N)/N= 3dB, without any preamplifier :
-120dBm @400kHz
-120dBm @1MHz
-120,5dBm @3,5MHz
-120dBm @7MHz
-119,5dBm @28MHz
-119,5dBm @52MHz
-118dBm @78MHz
-SFDR = 85dB (This value can be different with other Soundcards and PC's) Screenshoot with -20dBm input level , Signal Generator HP8640B
-Filter 1 insertion loss: 1dB @3,7MHz
-Filter 2 insertion loss: 1,8dB @7MHz
-Filter 3 insertion loss: 1,5dB @21MHz
-LPF-Filter insertion loss: 0,7dB @1MHz
- IF amplifier output clipping level: 2,45Vp @ -13dBm RF input level
- IF (I and Q output signal) bandwidth: 155 kHz @ -6dB
- Power supply : 5V / 155mA (+15mA with LCD module)
- USB2.0 interface, only USB powered (no external supply are required)
- high speed divider/clock generator CYPRESS CY22393/4 (for the tuning range: 0,1 - 2,5 Mhz)
- new low jitter clock generator SILICON LABS Si570 LVDS (or CMOS)
- interface for optional LCD
- interface for optional boards (transmitter, preselector ecc.)
- 3 Bandpass filter on board + 1 Lowpass filter on board + filter bypass (broadband input)
- IF-Chain with rail-to-rail OP-AMPS for 5V
- I/Q outputs for PC Sound card
- I/Q optional differential outputs for professional PC Sound cards
- PIC18F4550 Controller with USB-Bootloader
- DLL support trough USB interface for Winrad by I2PHD & PowerSDR-IQ
- PCB: dual layer, 80 x 100mm
