ON1BES Labo 2016              Basic SDR-Upcoverter v1.0


 Only English version

The smallest SDR Upconverter you known? Let me know !
HandThis version 1.0 is a version 'back to basic' . There is only one HF input and one VHF output. You can use an old IE-500 or  SBL-1 mixer , or a modern ADE-1 diode-mixer, and to gonna use of real (air) coils. So there can not be a filter characteristic change on higher frequency's. The oscillator is 125MHz, so all SDR dongles can be used.
The entire board is designed for SMD components, and ready-made available coils can be used. But it is still possible to use hand-made (air)coils, if you make them small. The filter values were then also be adjusted, in order to be able to use default values of inductances and capacities. Filter calculations are done with RFSim99.
Bandplan :
To with our RTL-SDR TV Dongle be able to receive anything under the 30Mhz, we need a converter that converts the frequency of 0-30MHz to a frequency above 50 MHz which we can do receive on our RTL stick. Check out the band plan below to see the mixing system :
* An old E4000 dongle receive from 52MHz to 2200MHz, a new R820T2 dongle receive from 24MHz to 1760MHz.
Bandplan
Click fig. for bigger view
The schematic for a ADE-1 version :
Upconv 1.0 ade1
Click fig. for bigger view
The schematic for a IE-500 or SBL-1 version :

Upconv 1.0 sbl1
Click fig. for bigger view
The incoming
HF signal passes through a 0 to 30MHz sharp Cauer low-pass-filter, and the antenna signal is presented to the diode-ring mixer (ADE1, IE-500 or SBL-1). A active crystal oscillator of 125 MHz with a 8 dB attenuator at the output path also goes to the diode-ring mixer, and is mixed with the incoming signal. The mixede output signal then goes to a 
high-pass-filter starting from +/- 124MHz, and has the intention to suppress strong signals from the FM radio band.
The power of the crystal oscillator happened via a short wire with a USB plug (of a faulty PC mouse), and with a 47 ohm resister gives this 3.4V to the Crystal block (beware of the numbers - which is sometimes different!). The remainder of the circuit does not require power.
Input connector is a SMA type (could be an RCA Phone chassis type also). Output is soldered with a short coax (15 cm) wire and MCX-connecter and goes directly to the dongle antenna-input. This cable can be a re-used one from the stock antenna that was supplyed with your dongle.
Importend note: it we take the SBL-1 IF pin 5 as input, we can receive from almost 0MHz to 30MHz insteed 100kHz to 30MHz.

Printboard and build :
Assembly ADE-1
Board
Photo ADE
Assembly ADE-1
Board ADE-1 Photo
Assembly
Board SBL-1
Photo SBL1
Assembly SBL-1
Board SBL-1 Photo
Click a photo for bigger view.
Circuit bord is double sided. Drill the needed holes, and remove copper arround holes with a 3mm drill.

Making the coils :
Coils 330-390nH
Coils 39-47nH
Coils UHF
The HF Coils
The UHF Coils Solder UHF Coils without ends
Click a photo for bigger view.
You can make the coils easy for the input and output filters ( coils 330nH and 390nH on a plastick ear-stick = 2,5mm ). The dimentions are :
- the 390nH coil L1 : Ø wire = 0,25mm, ear-stick Ø= 2,5mm, windings = 16, lenght = 4mm.
- the 330nH coil L2 : Ø wire = 0,25mm, ear-stick Ø= 2,5mm, windings = 14, lenght = 4mm.
- the 39nH coils L3, L4, L5 : air-coil, wire Ø = 0,5mm, temporary ear-stick former  Ø = 2,5mm, windings = 4, closed together.
- Edit: the 47nH coil L3 and L5: are replaced with 39nH. See schematic. 47nH is not used.
Attention : the UHF coils L3-4-5 are pure aircoils (without former) . A UHF air coil with a plastic former is not stable on that frequency.
Also, the solder-ends are to be max. 2mm, not more. See photo.

Characteristics of the filters :
The filters  are calculated with RFSim99, an old Windows8 program with great prestations. You must first have a installed version on Win XP (32 Bit) , and then copy the files on Win10, or it does not work. Here, you see only the filter responce diagram(s) :

Filter 30MHz
Filter 125 MHz
The LP 30 MHz filter
The HP 125 MHz filter
Click a photo for bigger view

Results :

If HDSRD as software was used, which has an ability to get the frequency right the weather, and take into account the crystal of 125 MHz. Already at the first start it was clear that there was life in the circuit. My first test antenna was an indoor Magnetic Loop with C-alignment , enough to have some reception.
Later builds of Up-converters are tested with a outside Mini Whip antenna with very good results.

HSDR on the VLF Band :
HDSDR
Click a photo for bigger view.
For receiver results and screens , refer to my other page : HF Upconverter V4.0
Downloads :

none


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