DG8SAQ VNWA Kit Assembly Manual - SDR-Kits

SDR-Kits.net DG8SAQ USB-VNWA 1.1, 1.2 & 1.3 Assembly Manual 1.3a 

DG8SAQ Vector Network Analyser USB-VNWA Interface Assembly Manual 

USB-VNWA v1.1 & v1.2 & v1.3 PCB version 

Link to current USB-VNWA assembly manual 

www.SDR-Kits.net 

Fig 1: 

USB-VNWA PCB assembly – Version with internal PCB connectors (Kit 4) hence Dsub9 and Audio 

socket not shown. USB socket is installed in as J9, hence J3, L1 and L2 are not required 

Contents: 

1. Introduction 

2. Kit Information 

3. USB-VNWA Interface preparation 

4. USB-VNWA interface Printed Circuit Board Assembly 

5. USB-VNWA Interface Commissioning 

6. Faultfinding 

Appendix 1 – Component Values 

Appendix 2 – Component Placing v1.1 PCB 

Appendix 3 – Component Placing v1.2 PCB 

Appendix 4 - Component Placing v1.3 PCB 

SDR-Kits.net © 2009 by Jan Verduyn G0BBL SDR-Kits & Thomas Baier DG8SAQ 1 of 29


1. INTRODUCTION 

The Vector Network Analyser (VNWA) described by Thomas Baier DG8SAQ in his article “A Small, 

Simple, USB-Powered Vector Network Analyser Covering 1 kHz to 1.3 GHz in QEX 

January/February 2009 is orginally controlled via the Parallel port of the Personal Computer. 

This new add-on USB-VNWA Interface card was developed by Tom to allow control of the VNWA 

from the Personal Computer via the popular USB Bus. The USB-VNWA interface PCB contains a 

USB hub device to extend the USB bus to the PCM2900 Audio Chip and the AtMega88 Controller 

chip on the PCB. There are two options: 

• For those who already have built and use the VNWA PCB fitted with DB9 connector: 

The USB-VNWA is connected to the VNWA PCB assembly via a D9sub connectors through 

which VNWA +5V Power and VNWA control signals are routed and a short 3.5mm to 3.5mm 

stereo cable connects both audio sockets. This routes the VNWA Reference and multiplexed 

Forward and Reflected Audio signals to the PCM2900 Audio Codec for transmission via the 

USB bus to the Personal Computer for subsequent processing. 

• Complete USB-Controlled VNWA Kit 4: introduced in December 2009 (s/n 324 and up) uses 

internal Single in Line (SIP) 0.1" connectors to mate these signal between the two PCB 

assemblies. 

2. KIT INFORMATION: 

These USB-VNWA Kit assembly instructions are applicable to USB-VNWA v1.1, v1.2 and v1.3 

PCB size 98mm x 62mm – same size as VNWA PCB. 

There are no practical differences between USB-VNWA Interface v1.1 and v1.2 Printed 

Circuit boards, except that v1.2 has R41 and R42 eliminated and has two minor mechanical 

changes in preparation for producing an assembled VNWA version later in 2009. Appendix 2 

has v1.1 component placing whilst Appendix 3 has the v1.2 PCB component layout. 

V1.3 PCB has LED D1 is reversed and the location of R1 has changed. Appendix 4 has 

component placing for this PCB version 

A VNWA Enclosure is available which allows both PCBs to be fitted on top of each other. 

Operational Specification 

• Power Supply: Powered from +5V 500mA Power Supply or directly from Personal Computer 

USB port capable of sourcing 500mA. 

• Personal Computer with minimum 1GHz processor and minimum of 64 Mbyte memory 

recommended and USB V1.1 or V2.0 connectors and a standard sound card under Microsoft 

XP, Vista Home edition or Windows 2000 Operating System. Installation of DG8SAQ 

Firmware Drivers and DG8SAQ VNWA USB Software Application required. 



Note: The VNWA application has been successfully operated on Pentium III Laptop with 600 

MHz Processor, operation on computers with lower specification cannot be guaranteed. 

USB-VNWA Interface Kit Support 

Please use the DG8SAQ VNWA reflector to check for announcements, documentation 

updates and to share your experiences building and using the DG8SAQ VNWA. 

http://groups.yahoo.com/group/VNWA/ 

Please contact Jan (email: sdrkits@gmail.com ) for kit hardware issues, short shipments 

and Tom to report any software bugs. 

Kit Assembly Manual Errors and updates 

No responsibility is assumed for any errors in this document. All information is given in good 

faith based on information gathered from Kit builders. 

If you become aware of any errors or have any suggestions to improve the information in this 

document please email Jan G0BBL via sdrkits@gmail.com New Document revisions will be 

announced in the VNWA group and are available from the www.SDR-Kits.net Website. 

Other Links for Information 

DG8SAQ VNWA Home page: http://www.mydarc.de/dg8saq/VNWA21/index.html 

SDR-Kits VNWA Home page: http://www.SDR-Kits.net/VNWA/ 

Copyright Notice: This project was initiated and designed by Prof. Dr. Thomas Baier 

DG8SAQ, who holds copyright to this design. Reproduction of the Printed Circuit Board and 

the VNWA circuit schematic is not permitted without written permission of the copyright 

holder. Reverse Engineering and Commercial reproduction is not allowed. 

Please see SDR-Kits Ordering Terms and Conditions 

Acknowledgments USB-VNWA project: 

Tom - DG8SAQ – Concept – PCB Design & USB-VNWA Software and firmware 

Jan G0BBL – Kit Production – Kit Assembly Documentation - 

Big thanks to various USB-VNWA Builders for their help and useful comments!! 



3. USB-VNWA interface Preparation 

3.1 Introduction: 

If you already have assembled the VNWA Printed Circuit Board, you will find that the 

USB_VNWA is somewhat less challenging compared to assemble compared to the VNWA , 

however please pay attention especially when soldering the U4 PCM2900 and the U2 

TUSB2036 USB Hub. Do NOT fit the 28 pin IC socket until indicated. The 0603 

components should be soldered first as space quite tight near the socket. 

3.2 Bill of Materials Check: 

[ ] Check the contents of the items supplied as shown in Table 1. 

Caution: Observe Electro Static Precautions when handling ESD sensitive components. Do not 

remove ICs from packaging until required. 

DG8SAQ USB VNWA Control Board v1.1, v1.2 & v1.3 PCB – BOM 

ITEM QTY Remark Capacitors QTY Remark 

U1, U3 LE33 2 15p 2 red/black 

D2, D3 MBR0520 2 B25 27p 4 red/green 

U2 TUSB2036 1 1n 4 black 

U4 PCM2900 1 100n 19 red stripe 

Q1 IRLML6401 1 F8?85 1u 6 blue 

D1 LED 1 10u 7 

X1 6 MHz 1 

X2 12 MHz 1 Resistors 

F1 PFRA010 Fuse 1 or XF010 0R 3 0 or 000 

L1..L4 Choke 400mA 4.7uH 2 2 fitted 22R 7 22 

J26 3 pin 0.1” 1 47R 2 47R 

USB_VNWA PCB 1 68R 3 68 

J3 or J9 USB Socket 1 100R 6 100, 101 01A 

J23 USB out Socket 1 680R 3 681 

1K 4 102 or 01B 

J5 Db9 Male (or 5 & 4 pin SIP) 1 Note 1 1K5 6 152 or 1BB 

J24 AUDIO_JACK (or 3 pin SIP) 1 Note 1 10K 5 103 or 01C 

Db9 male IDC 1 Note 1 15K 8 153 or 1BC 

Db9 female IDC 1 Note 1 150K 2 154 or 1BD 

10 core cable 10 cm Note 1 1M 2 105 

3.5 mm Plug stereo 2 Note 1 

IC socket 28 pin 0.3” 1 

I ATMEGA88-16PI 1 Programmed 

Circuit Information 1 Copyright 

License Key information 1 

Note 1: If VNWA Kit 4 is ordered 3 pcs SIP Male 0.1” connectors (5pin, 4pin and 3pin) 

will be supplied instead of the connectors listed as Note 1. The SIP connectors allow 

the USB-VNWA PCB to mate directly with VNWA PCB. 

Table 1: Bill of Materials for Production Kits 



3.3 Printed Circuit Board Preparation 

[ ] Check whether your kit contains version contains USB-VNWA v1.1, v1.2 or v1.3 PCB If 

your version is different check whether you have the correct USB-VNWA assembly manual 

applicable to your particular PCB version supplied. 

Appendix 2 has v1.1 component placing whilst Appendix 3 has the v1.2 PCB component layout 

and Appendix 4 has the v1.3 component placing 



4. USB-VNWA Interface Printed Circuit Board Assembly 

[ ] Inspect USB-VNWA PCB for rough edges and rasp with fine file if necessary. 

[ ] Place PCB on black anti-static mat supplied with VNWA PCB and set the soldering 

station to 330°C = 630°F 

[ ] Caution: Observe ESD precautions and correct orientation in the following 2 

steps as shown in Appendix 2 or Appendix 3 

[ ] Install U4 PCM2900 – observe dot (pin 1) as shown in Appendix Component 

Placing 

[ ] Install U2 TUSB2036 – observe dot (pin=1) as shown in Appendix Component 

Placing 

[ ] Install resistor 0R (marking 0 or 000) R28 R41 (R41 is NOT used on 

v1.2 and v1.3 PCB!!) 

[ ] Install resistor 22R (marking 22) R2, R3, R17, R18, 

R35, R36 

[ ] Install resistor 47R (marking 47) R39 

[ ] Install resistor 68R (marking 68) R21, R22 

[ ] Install resistor 100R (marking 101 or 01A) R29, R30, R31, R32, R33 

[ ] Install resistor 680R (marking 681) R38, R40 

[ ] Install resistor 1K (marking 102 or 01B) R1, R7, R34 

[ ] Install resistor 1K5 (marking 152 or 1BB) R5, R6, R19, R26, 

[ ] Install resistor 10K (marking 103 or 01C) R23, R27, R37 

[ ] Install resistor 15K (marking 153 or 1BC) R10, R11, R12, R13, R14 

R15, R16 

[ ] Install resistor 150K (marking 154 or 1BD) R8 

[ ] Install resistor 1M (marking 105 or 01E) R20 

[ ] Install capacitors (1uF 0805 blue) C20, C21, C22, C23, C36, 



[ ] Install capacitors (100nF 0603 red) C2, C4, C6, C8, C10, 

C12, C15, C16, C17, C24, 

C25, C26, C29, C32, C33, 

C34, C37, C38 

[ ] Install capacitors (1nF 0603 black) C5, C31, C35 

[ ] Install capacitors (27pF 0603 red/green) C3, C7, C27 

[ ] Install capacitors (15pF 0603 red/black) C28 

[ ] Caution: Observe orientation as shown in Appendix 2 or 3 (black stripe or + 

symbol) in the following 2 step. (For Tantalum capacitors supplied in the Kit the 

BLACK STRIPE indicates the + terminal.) 

[ ] Install capacitors (10uF) C1, C9, C11, C13, C14, 

C18, C19 

[ ] Install diodes (MBR020L marking 1B28 or B25) D2, D3 

Caution: Observe orientation of black stripe or the letter “c”. Use a 5x magnifier to 

detect the small raised edge at one end of the case of the diode, which indicates the 

cathode. 

[ ] Install LE33 U1, U3 

[ ] Install IRLML6401 Q1 (mark F8?85) 

[ ] LED D1 (Connect the Anode (Longer lead 

to the square pad) 

[ ] Crystals X1 (6 MHz) X2 (12 MHz) 

[ ] Fuse XF010 or PFRA010 F1 

Note: 

In the following steps the USB-B connector is installed in position J9 to suit the 

SDR-Kits VNWA Enclosure which has USB connection at the rear. If you require the 

USB-B connection on the front panel (not recommended) then install the USB-B 

socket provided in position J3 instead of in position J9. 

[ ] Install USB-B Connector J9 

[ ] Install USB-A Connector J23 (optional connector) 

[ ] Choke Inductor 4.7 uH L3, L4 when J9 installed 



Alternatively as L1, L2 when J3 installed 

[ ] Install 3 pin connector J26 (Optional for S-parameter control) 

[ ] Install 28 pin DIL IC Socket Caution Observe notch is located 

as per Appendix 2 or 3. (points toward 

X2) 

Caution: 

In the next step either DB9 connectors or SIP connectors are installed depending 

whether connections with VNWA PCB is internal (SIP) or external (DB9) 

[ ] Install correct type of connectors for J5 (either DB9 Male or 5 pin and 4 pin male SIP) 

[ ] Install correct type of connector for J24 (Audio Connector) (3.5mm Audio socket 

or 3 pin male SIP) 

Caution: Observe orientation in Appendix 2 or 3 in the following step 

[ ] Install programmed controller Atmega88 in 28 pin socket I1 so notch points to X2 

[ ] This completes PCB assembly. check all components and joints with x3 

magnification 

Note: 

D4, D5 and R42 is not installed on v1.1 PCB and higher. 

R41 is not present on v1.2 and v1.3 PCB. (0 Ohm replaced by track) 



5.0 USB-VNWA Commissioning and Final Assembly 

Caution: In the follow step separate instructions are given depending whether external (DB9) 

connectors or Internal connectors (SIP) are fitted 

5. 1 USB-VNWA Interface Assembly and Checks (External Connections DB9 connectors) 

Introduction: Commissioning the USB-VNWA PCB assumes that the VNWA PCB fitted 

with DB9 Socket has already been commissioned and is fully operational using the Parallel 

port interface. If this is not the case then 

[ ] Perform the following checks on your VNWA board for compatibility 

1) If fitted check whether R97, R98, R99, R100 and R101 are 0 Ohms. If not replace by 0 

Ohm (wire) link 

2) Check whether R52 = 150K (marking1BD) R52 is fitted between pin 1 and pin 2 of U23 

[ ] Plug the USB-VNWA Interface card into the D9sub Connector of the VNWA PCB assembly 

[ ] Use a audio cable with 3.5mm stereo plugs on either end to connect VNWA Audio socket to 

the USB-VNWA Audio socket 

5.2 Kit 4 VNWA PCB and USB-VNWA Assembly (Internal Connections SIL) 

[ ] Fit 3 pcs 8mm spacer on the VNWA PCB assembly. The correct sequence is: 

3mm 6mm long plastic screw, nylon washer, VNWA PCB, nylon washer and 8mm spacer. 

[ ] Carefully mate the USB-VWA PCB into the VNWA as shown in Fig 2. below. Fit nylon 

washer and 12.7 mm threaded spacer both sides of J5. Fit nylon and a 3mm plastic screw into 

the spacer under the 3rd hole. 



fig 2: VNWA Kit 4 (internal connections) PCB mounting detail 

5.3 DRIVER INSTALLATION FOR WINDOWS XP 

Introduction: In this section a driver needs to be installed on your Personal Computer in order 

to recognize your VNWA. Note: Only 32 bits Windows Operating Systems 

are supported at the present time because Microsoft requires Digitally signed Drivers 

for their 64 bit OS. 

Caution: Do Not connect the VNWA to your personal computer when installing the Driver. 

[ ] Download the Drivers from: 

http://sdr-kits.net/VNWA/USB-VNWA/AVR-USB-Driver.zip 

[ ] Unpack the Drivers as shown in Fig 3. A directory "AVR-USB-Driver" should be visible with 

the files as shown. 



fig 3: AVR-USB-Driver and Driver files shown after unpacking 

[ ] Connect the VNWA to the Personal Computer USB socket with a USB cable. 

A message will be displayed: 

After about 5 seconds the message below should be displayed 



• Select “No, not this time” 

• Press “NEXT” 

The following screen should now be displayed: 

Deselect “Install the software automatically” 



Select “install from a list or specific location” 

Press “Next>” 

The following screen is displayed 

• Deselect “Search removable Media” 

• Select “Include this location in the search” 

• Press “Browse” 

• Select Folder AVR-USB-Driver 

• Click “Ok” 

• Press “Next>” 

• Software is being installed 



When successfully installed, following message displayed: 



Once DG8SAQ Driver installation is installed three messages may be displayed and/or three 

audible are sounded whenever the USB-VNWA is connected to the PC: 

• USB-Codec detected PCM2900 

• USB Human Interface detected TUSB2036 chip 

• USB-Controller detected ATMEGA88 

Note: Windows Vista Driver Installation: 

Procedure how to download the DG8SAQ Driver for Windows Vista is provided 

in the following link: Vista Driver Installation 

5.4 USB-VNWA Application and Helpfile Installation 

Introduction: In this section the VNWA Application and Helpfile are installed. 

[ ] Download and unpack the current USB-VNWA Application Software in a new separate 

directory from: 

http://groups.yahoo.com/group/VNWA/files/A1 DG8SAQ/ 

Note: You need to be a member of the VNWA Yahoo group to access this folder. 

Make sure you select the "CURRENT" production Software for installation. 

(Experimental USB_VNWA releases may be made available which you should only use after 

you are familiar with CURRENT production Software) 

[ ] Download and unpack the VNWA HELPFILE in the same directory as in previous step 

Once complete the four files shown in fig 4 below should be present. 

Note for Vista 32 users!! To display the Helpfile you may need to load an additional file 

WinHlp32.exe from Microsoft See http://support.microsoft.com/kb/917607 for details. 

fig 4: USB_VNWA Application files after downloading 



5.6 START VNWA APPLICATION AND HELPFILE 

[ ] Run USB-VNWA Software by clicking on VNWA Application icon. 

[ ] Select “Options” and “Setup” and “Interface Type” and click “USB Mode” The following 

screen in fig 5 should be displayed 

[ ] Next select “USB Setting” 

fig 5: USB Mode Selected 

[ ] Press “Rescan USB Bus” and check whether the USB bus drivers are detected as shown in 

fig 3. “DG8SAQ VNWA USB Controller found” 

[ ] Enter the License code provided with your kit in the field shown in fig 5. 

Note the 2 colons, the first colon is between the family name and the licensing Date. The 

second colon terminates the License code. Example: Jan.Verduyn:2009.05.01: 

[ ] Close (Exit) down the DG8SAQ VNWA application. This saves the license code on your 

computer. 

. 



fig 6: Entering License Key – after Rescan USB Bus 

[ ] Start up the DG8SAQ USB-VNWA application once more to allow the license code is 

recognized. 

[] Select “Options” and “Setup” and “Interface Type” and click Test USB Interface. 

This test should be succesfully completed, if the licence key was correctly stored. 

[ ] Now select “USB Settings” and verify whether “USB Audio Codec” has been selected as 

shown in fig 7. 

For VNWA with DB9 (external connections) Select “Reference = Left Channel” – otherwise 

Reference will NOT be detected. 

For kit 4 (internal connections) select "Reference = Right Channel" 



Fig 7: USB Setup Screen 

[ ] Next select “Audio Settings” and press on “TestAudio “ and select “Reflect” 

With VNWA TX Port not terminated typical Audio Levels as shown in fig 8 should be 

displayed. 

[] Connect TX and RX port with a short SMA cable and press "THU". A similar waveform 

as shown in fig 8 should now also be shown. 

[ ] If Audio Reference is not visible, check whether the VNWA and USB-VNWA audio sockets 

are connected via a stereo 3.5mm to 3.5mm cable. 



Fig 8: Audio Settings Screen 

[ ] IMPORTANT - Please check you can open and read the VNWA HELPFILE: 

Open the VNWA Helpfile and take out time to familiarize yourself 

with the VNWA application: particularly with sections shown in Fig 9: 

- Installation & Configuration 

- Calibration 

- Known Issues 

- Verification of Proper Operation (Troubleshooting section) 



Fig 9: Helpfile - Important sections: 

5.6 Final Assembly of PCB Assembly: 

Caution: Only after the USB-controlled VNWA has been fully tested, should the USB_VNWA 

Interface PCB is fitted in the Enclosure. 

Note: it is recommended that the Printed Circuit board is directly soldered in the metal 

chassis. Use a 50W or 60W Soldering iron with a big tip. If the chassis has a blue/grey 

zintec coating, remove this coating with a small wirebrush or a small hobby knife. On 

later versions the chassis is tinplated for easy soldering. Coat the joints first with Acidfree 

flux approved for Electronic PCB assembly. With a proper soldering iron heat 

needs to be applied to the joint for about 5 seconds before solder will melt and make 

the solderweld. 



[ ] Refer to fig 10. Carefully separate the VNWA PCB and insert into the chassis and screw 

washer and nuts on both SMA connectors - Do not tighten. 

[ ] Internal Connectors: Carefully align the ground plane side of VNWA PCB at a distance 

25.3mm from the edge of the chassis on all three sides. Make sure the gap between PCB 

and chassis is as shown in fig 10. then tighten SMA screws to hold the PCB in place. 

[ ] For VNWA PCB with external female DB9 connector, fit the rear/bottom of the enclosure 

panel and align the VNWA PCB within the chassis and tighten SMA screws. then remove 

rear/bottom panel. Check the gap between PCB and Chassis is as shown in fig 10. 

[ ] Coat the joints with acid free flux, approved for PCBs and electronic components and solder 

as shown in fig 10. It is normal that heat needs to be applied first for about 5 or 6 seconds to 

the joint before the solder will flow freely to make the solderweld. Use de-soldering braid or 

(coax) cable braid to bridge the gaps on between PCB and chassis as shown. 

[ ] Turn over the chassis and solder the SMA connectors on the other side. 

Fig 10: Soldering VNWA PCB in Chassis (shown for internal connectors) 

5.7 Assembly of VNWA Enclosure 



[ ] DB9 External Connectors: Fit the USB-VNWA PCB to rear/bottom panel using the 2 

screws provided with the DB9 male connector. Fit to the Chassis with the VNWA PCB and 

using 2 screws provided with the DB9 female connector on the VNWA PCB. Fit enclosure 

cover with the black 3mm 6mm long black screws provided. 

[ ] Internal Connectors: Carefully plug the USB-VNWA PCB into the VNWA PCB and fit 

spacers and plastic screws as shown in fig 10. Fit rear/bottom enclosure panel and enclosure 

cover and fasten loosely with black 3mm 6mm long black screws provided. (Caution: The 

enclosure top cover must be fitted to ensure proper clearance for the 6mm screw near USB-B 

connector. Fit 2 3mm plastic screws with nylon washer and screw through the bottom panel 

into the spacers. Align before tightening all 8 screws. 

[ ] Fit the 4 stick-on rubber feet provided to each corner of the bottom of enclosure. Make sure the 

surface is dry and free of grease otherwise clean first with alcohol. 

Two connections cables are required to connect USB-VNWA PCB to the VNWA PCB after fitting 

in the enclosure. 

5.8 External Cable Assembly (DB8 External Connectors only) 

Cable 1: 

Dsub connection cable 

[ ] A short cable needs to be made up consisting of the D9 IDC Male connector to the D9 IDC 

Female connector. The length of the cable is 5cm.. Fig 11. shows typical assembly for the 

SDR-Kits ready drilled enclosure where VNA and USB-VNWA Interface PCBs are mounted 

with the copper sides facing at a distance of 8.1mm. 

[ ] Reduce the 10 core flat cable provided to 9 cores using scissors. 

[ ] Identify the “stripe” denoting pin 1 on top left corner of the D9sub Male connector. when 

looking at the pins. Position the flat cable in this connector so the blue (or marked)core is on 

the side (pin1) (see fig 11). 

[ ] Place connector in a Vice and whilst holding connector cable squarely aligned, press the clamp 

onto the male connector by operating the Vice, until the rear clamp clicks in place. 

[ ] Identify pin 1 (top right corner) of the D9 Female connector when looking at the front holes. 

Position the flat cable in this connector so the blue or marked core is on the side (pin1) 

[ ] Place connector in a Vice and whilst holding connector cable squarely aligned, press the clamp 

onto the female connector by operating the Vice until you hear the clamp clicks in place. 



Fig 11. D9sub IDC Connection cable assembled to suit 

SDR-Kits ready drilled Enclosure. Distance between connectors is 25 - 30mm 

Cable 2: 

Stereo audio cable – with 3.5mm stereo plugs at either end 

[ ] Cut 2 length of 7cm wire (not provided) and solder between the two stereo plugs 

provided. Check with an ohm meter. Perfectionists may use screened cable however this 

this is not necessary. This short cable plugs into audio sockets of the two PCBs. 

This completes USB_VNWA Kit assembly 



6. USB-VNWA Faultfinding 

Please consult the DG8SAQ USB-VNWA Helpfile - Section sTroubleshooting and "Known 

Issues (see fig. 9.) 

• USB Not recognized - Is DG8SAQ Driver properly installed? 

USB Enumeration consists of 3 stages: a) detection of USB Hub, b) detection of Atmega88 

Controller, and c) detection of PCM2900 Audio Codec. 

Please consult the DG8SAQ USB-VNWA Helpfile. “USB Troubleshooting Guide” 

• Are 12 MHz or 6 MHz Crystals Oscillating? Check with Scope with x10 Probe 

• Audio sockets connected with 3.5mm audio stereo cable? 

• Check VNWA Audio Configuration: Is USB-Codec selected? 

• Is another USB device using the DG8SAQ driver connected to the Personal Computer ? (for 

example Softrock Radio with QRP2000 Synthesizer) 

Also Check the VNWA reflector http://groups.yahoo.com/group/VNWA/ for possible answers 



APPENDIX 1 – USB-VNWA Interface - Component Values 

USB VNWA Interface Board Component values 

C1 10u D1 LED R1 1k 

C2 100n D2 MBR0520 R2 22R 

C3 27p D3 MBR0520 R3 22R 

C4 100n D4 Omit R5 1K5 

C5 1n D5 Omit R6 1K5 

C6 100n F1 PFRA010 Fuse R7 1k 

C7 27p I1 ATMEGA8-16PI R8 150K 

C8 100n J3 USB_IN R10 15K 

C9 10u J4 out R11 15K 

C10 100n J5 DB9 R12 15K 

C11 10u J7 AUDIO_JACK R13 15K 

C12 100n J9 USB_IN R14 15K 

C13 10u J23 USB_OUT R15 15K 

C14 10u J24 in R16 15K 

C15 100n J25 6_ports R17 22R 

C16 100n J26 3pins R18 22R 

C17 100n L1 400mA choke R19 1K5 

C18 10u L2 400mA choke R20 1M 

C19 10u L3 400mA choke R21 68R 

C20 1u L4 400mA choke R22 68R 

C21 1u Q1 IRLML6401 R23 10k 

C22 1u I1 28 p socket R26 1K5 

C23 1u R27 10K 

C24 100n U1 LE33 R28 0R 

C25 100n U2 TUSB2036 R29 100R 

C26 100n U3 LE33 R30 100R 

C27 27p U4 PCM2900 R31 100R 

C28 15p X1 6 MHz Crystal R32 100R 

C29 100n X2 12 MHz Crystal R33 100R 

C31 1n R34 1k 

C32 100n R35 22R 

C33 100n R36 22R 

C34 100n R37 10k 

C35 1n R38 680R 

C36 1u R39 47R 

C37 100n R40 680R 

C38 100n R41 0R (v1.1 only) 

R42 omit 



APPENDIX 2 – USB-VNWA Component Placing V1.1 PCB 



Appendix 3 – USB-VNWA Component Placing V1.2 Component placing 

(c = D2 and D3 cathode - + = black strip on Tantalum Capacitor 



Appendix 4 – USB-VNWA Component Placing v1.3 PCB 

Shown for External DB9 connectors and VNWA Kit 4 Internal SIL connectors 



APPENDIX 5 

DG8SAQ Circuit Diagrams 

This Appendix is supplied to Kit builders with the Kit parts

DG8SAQ VNWA Kit Assembly Manual - SDR-Kits

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