tiny SCR Preselector  

tiny SCR Preselector

Software Controlled Radio Preselector via USB or I2C bus. Digital tuning

It provides filtering of R.F.spectrum to reduce broadband signal energy into the receiver..

1.8MHz to 30MHz, five bands, tunable Band Pass Filter.

A less complex version of the SCR Preselector.

Assembled and kit versions.

(Windows 2000, XP, Vista and Windows 7 (32 & 64 bits) OS)

Suitable for Software Define Radios and analogue receivers.

Tiny SCR Preselector on Winrad v1.6.1 and WinradHD

The Tiny SCR Preselector frequency setting and band selection is synchronized dynamically with any radio supported by Winrad v1.6.1 and WinradHD.

		Tiny SCR Preselector on Winrad page

Now tiny SCR Preselector supported on FlexRadios!

From August 13, 2010, Flexradio models Flex-3000, Flex-5000 and Flex-5000C are supporting the tiny SCR Preselector, I2c controlled, via Flexwire bus.
For more details: http://support.flexradio.com/Downloads.aspx

PowerSDR™ 2.0.8 Release notes.

Interconnecting with FlexRadios

The tiny SCR Preselector is oriented to complement radio projects due to its modular design.

The tiny SCR Preselector can be used with SDR and analog radios.

It is connected in line between the antenna and your receiver. (transceiver with Dual By-Pass relay accessory).

The tiny SCR Preselector can be controlled from a personal computer via USB or from a radio or digital system supporting
I2C bus protocol.

Features:

■ Five bands tuneable Band Pass Filter bank for HF Bands covering 1.8 to 30 MHz.
■ Passive filters.
■ There are no active switching or amplifier devices in the signal path therefore it does not contribute to IMD (Intermodulation Distortion).
■ Removes strong signals radiated back to the antenna from SDR quadrature mixers.
■ Digital tuning. Eight bits digital variable capacitor.
■ High linearity (IP3). Suitable for Software Define Radios and analog radios.
■ Tuning coil wound on large toroidal T-200 core, avoiding saturation in front of large signals.
■ I2C Bus or USB control modules options.
■ Locked to a radio performs tracking tuning function.
■ Its modular design lets an easy implementation on your projects.
■ Power supply: 12Volts DC/ 0.250Amp max.
■ Board dimensions: 152mmx75mm( 5.984x2.953in)

USB control option

■ PC controlled through graphical user interface (GUI).
■ Full speed USB v2.0 compliant.
■ Plug and Play feature.
■ Runs underWindows 2000, XP, Vista and Windows 7 (32 & 64 bits) OS.
(Windows 2K users need to update Framework from Windows Update site)
■ Board dimensions: 62mmx50mm( 2.441x1.969in)

I2C bus control option

■ 16 bits standard I2C Bus serial bus interface.
■ Support 100Kbits/s and 400kbits/s FAST I2C Bus protocols.
■ Auxiliary Input/Output ports to implement external controls and/or signalling.
■ Up to eight control modules can share the same I2C Bus.
■ Compatible with most microcontrollers.
■ Board dimensions: 70mmx47mm( 2.756x1.85in)

User manual

Assembly manual

I2C bus control module

The tiny SCR Preselector should be preferably encloused in a RF tight box due the antenna effect of its large coil that easily gathers nearby signals or noise.

The follwing pictures show the tiny SCR preselector assembled on metallic enclosure from Hammond model 1455T1601.

Dimensions are: 160mm X 160mm X 51mm. (6.29 x 6.29 x 2 inch)

Boxed tiny with USB control

Boxed tiny with I2C bus control

Project example with tiny SCR Preselector by DJ8OM,Oskar Mayer.
He uses the tiny SCR Preselector with Flex SDR-1000, SDR-IQ and nine versions of SoftRock.

The Software.

The Software. USB control mode.

The software program on the PC runs under Windows 2K, XP, Vista and Windows 7 (32&64 bits) Operate Systems.
(Windows 2K users need to update Framework from Windows Update site.)
The user through the Graphic User Interface commands the Tiny Plus SCR Preselector.
The program can work at the same time with any SDR software running on the PC, without interference allowing to the user to control both simultaneously.

1- Band selection.
Click over wanted band button to change.

2- Tuning Decrement.
One step frequency decrement. One step increment of capacity.

3- Status bar.

4- Tune Reference Dial.
Displays the tuning value in picoFarads.
The tune reference is expressed in picofarads with values between 10pF and 255pF.
Sliding right or left the tuning knob increases or decreases the band-pass frequency.
Notice due to the response of series tuned circuits, the attenuation of the pass band filter increases with less capacity. A good practice is to avoid smaller values.

5- Tuning knob
Performs tuning moving left or right. Also by pressing left or right arrows on the keyboard or turning mouse wheel. Adjust to maximum signal or background noise.

6- Tuning Increment
One step frequency increment. One step decrement of capacity.

7- Memories. Five memories per band 25 in total.
There are up to five memories per band (25 in total). Clear-Store and Recall functions for each memory position.Store function lets write a descriptive text label.

Optional Accessories

Enclosure only for kit modules. USB or I2C versions available. Includes accessories.

USB or I2C versions front enclosure view	I2C version rear view	USB version rear view

General Purpose Dual By-Pass relay

150 Watts RF power rating. PTT or Keying line activated.

It is designed to by-pass the Input and Output RF ports of any device in line with your transceiver or transmitter.
A typical application includes inserting between antenna and a transceiver or transmitter a preselector, preamplifier or filter device.
On transmission switchover, via PTT or Keying line, the Input and Output RF ports of the device are by-passed avoiding being overloaded.
Two switching configurations are available:
- Default By-Passed.
- Default NO By-Passed. (see below).

- Frequency range: DC - 60MHz
- Insertion loss: 0.2 dB @ 60 MHz
- Isolation: 60 dB @ 60 MHz
- Power rating: 150 W
- Impedance: 50 Ohm
- SWR: 1.22 @ 50MHz
- Diode protection.
- Power supply: 12 Volts DC/68 mA
- Switching time:
- Set: 15mS
- Reset: 5mS
- External Dimensions: 40x37x111mm.
- Connectors: SO-239 Antenna/RTX; BNC RX IN/RX OUT
- BNC-BNC coaxial tails and complete shielded control cable with snap-on RFI-EMI suppressor ferrite cores   are provided.

Dual Antenna Relay page  

Tiny SCR Preselector - Flexwire I2C bus interconnection cables
(Shielded, EMI protection)

Tiny SCR Preselector is available in three versions.

The assembled and tested PCB modules version contains:

- tiny SCR Preselector. Band Pass Filter bank module and control module.
- IDC-ribbon interconnection cable.
- USB or I2C control module option.
- USB cable. (USB control module option)
- CD ROM including comprehensive user and assembly manuals, including    all software and USB driver for Windows Operate Systems.

- All parts needed to build the kit. Includes pre-progamed PIC microcontroller (USB option) and pre-winded impedance match transformers.
- IDC-ribbon interconnection cable.
- USB or I2C control module option.
- USB cable. (USB control option)
- CD ROM including comprehensive user and assembly manuals, including    all software and USB driver for Windows Operate Systems.

tiny SCR Preselector Kit version including USB or I2C control module option