This is the setup I'm looking for - a SDR with a bit of power output
that covers 160 to 10 meters - NEAT!!! Now just waiting for the
final kit - sure hope the price is where I can afford it.
73 de Ken H.
--- In firstname.lastname@example.org, "alexle188" <lee188@...> wrote:
> Hi all,
> I would like to provide some technical information of the
> The schematics and pcb design of the motherboard v3.5 (the Beta
> can be found under FILES->9V1AL->motherboard->v3.5 Photos of the
> motherboard v1.0 (the prototype pcb) can be found under PHOTOS-
> Intended use
> The Motherboard is designed to plug on top of the Softrock RxTx v6.3
> pcb. 4 footer connectors on the bottom of the Motherboard plug into
> the 4 receptacle connectors J1 to J4 on the Softrock V6.3
> With the Motherboard in place, the Sofrtrock Rx Tx v6.3 provides
> coverage from 160m to 10m for Rx and Tx WITHOUT the need to swap
> modules. All band switch, Rx/Tx, and Freq control can be done
> REMOTELY on the PC with a single USB port (using the UBW emulator
> firmware, see below).
> The 4 Rx BPF modules of the RxTx v6.3 plug into 4 receptacle
> connectors on the top of the Motherboard.
> The 4 Tx BPF's (similar to the Tx BPF in each of the 4 Softrock v6.3
> Tx BPF + PA modules) are onboard the one Motherboard. The
> also has the 2n2222a driver and BS170 PA that is found in each of
> 4 Softrock Tx BPF + PA modules).
> Thus if the Motherboard is used, there is no need to use any of the
> Softrock v6.3 Tx BPF + PA module.
> However, the Motherboard does NOT have inbuilt LPF's. (Each of the
> Softrock Tx BPF + PA module has one LPF specific for the band(s) of
> the module.)
> To meet FCC requirements for Tx, the user has to connect an outboard
> LPF bank between 2 connectors on the Motherboard (LPF-ANT and LPF-
> to provide the harmonics filtering before connecting the Sofrock
> v6.3's ANT output to the antenna (or external linear PA).
> Note that this outboard LPF bank is NOT supplied with the
> The user will have to buy or build his/her own LPF bank.
> You can see an example of a switched LPF bank in my setup
> (PHOTOS->9V1AL). More on this subject in the last portion of this
> The Motherboard band selection is via 2 logic bits, S1 and S0, to
> select one of 4 bands, similar to the Softrock v6.3's 4 modules:
> Currently, the USB-I2C interface does NOT have the firmware nor the
> signal pins to control the Motherboard band switching.
> (However, for those interested, another USB Si570 interface based on
> the UBW CAN be used to control the Motherboard band switching
> automatically. You need to load the firmware called UBW Emulator
> the UBW. The UBW will then emulate the USB-I2C interface as far as
> the PC is concerned. 3 pins from the UBW will control the Si570
> onboard the Softrock v6.3, and 2 pins from the USB will control the
> Motherboard for AUTOMATIC band switching according to the frequency
> selected. The UBW firmware and README file can be found under
> FILES->9V1AL->UBW emulator.)
> The band selection can be MANUAL as well, by applying +5V voltages
> GND to the S1 and S0 pins. Thus a remote DPDT manual switch can be
> used switch the filters as well.
> Another input, PTT, is used to switch between the Rx and Tx BPF's on
> the motherboard.
> The Motherboard provides an output keyline out (open drain output, >
> 100ma sink capability) for keying (active low) an external PA.
> The Motherboard requires a +5V supply, which can be taken from the
> Softrock v6.3 board.
> Theory of Operation
> The Motherboard uses 3 FST3253 bus switches to select one of 4 Rx or
> Tx BPF's, and enables/disables the Rx/Tx filters depending on the
> Care in the pcb design makes sure that the signal paths are short
> the I and Q signal traces are of approximately equal length from the
> switch. The "common" center taps of the I/Q transformers are
> decoupled to ground to prevent stray inductances and capacitances to
> cause phase shift of the I/Q signals.
> The Rx BPF switch over points have been carefully selected so
> smooth change over. From 160m to 10m, the Rx received signal is
> within 1 S unit when tested with a broadband constant noise source.
> The Tx side has been fine tuned such that to get 1W output from the
> Softrock v6.3, the audio I/Q drive required is approximately the
> from 160m to 10m:
> Band audio setting using PowerSDR
> 160 1.75
> 80 2.4
> 60 2.1
> 40 2
> 30 2.3
> 20 1.95
> 17 1.95
> 15 1.75
> 12 1.6
> 10 1.6
> As the Motherboard PA output does NOT have the LPF onboard (the
> Softrock v6.3 Tx BPF + PA modules HAVE the LPF onboard), an EXTERNAL
> or ADDON LPF is REQUIRED to meet FCC requirements if you are
> connecting the Motherboard/SR v6.3 to an antenna for Tx.
> Even for connecting the Motherboard/SR v6.3 output to an external
> linear PA, which will have its own LPF at the output of the linear
> it is ADVISABLE to insert the ADDON LPF between the 2 LPF connectors
> on the Motherboard to reduce harmonics and spurious of the linear PA
> In line with the purpose of the Motherboard to have band switching
> done remotely and automatically via the USB, the LPF should ideally
> remotely and automatically controllable.
> This is currently possible with the UBW Emulator firmware
> (FILES->9V1AL->UBW Emulator), which has 7 output pins to control one
> of 7 bands of an external LPF.
> Thus with the UBW Emulator firmware, the Softrock
> v6.3/Motherboard/ADDON LPF combination can be fully automatically
> remotely controlled by PC software such as PowerSDR for freq change,
> band switching, and Rx/Tx.
> We are currently designing a PIN diode switched LPF board capable of
> 5W that will be complementary to the Motherboard. It is still in
> design stage.