Project Introduction

General

This kit is a daughter board, designed by Jan G0BBL and Tony KB9YIG, that provides four electronically switched band-pass filters for the Softrock Lite + Xtall V9.0 RX, replacing the single-band daughter board in the original design.

The board can also be used with the earlier RXTX V6.3 and RX V8.3 kits. However, in those cases, the builder must supply the required +5 Vdc bus (and ground connection) to the HF-BPF board, there being no matching sockets therefor on the earlier boards.

If you use Rocky as your SDR, the project initially is manually switched, using two header pins and their associated jumpers. The automatic/electronic switching will be enabled later, via the various SDR programs implement band switching logic and the interface to the V9.0 RX's ATTINY45 or via the soon-to-be-developed new firmware for the ATTINY45.

PowerSDR and Winrad have enabled the programmatic switching of the board.

Filter VNA Tests

Mike Collins KF4BQ tested (on 13 December 2008) the completed board and the results can be found at this link.

Here is a link to the latest schematic from the reflector

BF-BPF is Now in Production

Here is a quote from Tony's announcement on 12/28/2008:

Jan, G0BBL, and Mike, KF4BQ, have each tested the 1.8 MHz through 30 MHz version of the electronically switched v9.0 BPF board board and report very similar results. The performance of the v9.0 receiver with this BPF merits moving to the production stage with this kit.

Production circuit boards are due in early this week and production kits should start shipping by Thursday of this week.

Kit price for the electronically switched v9.0 BPF is $13 for US/Canada and $14 for DX where mailing costs are included in each kit price.

(The 3.5 MHz through 30 MHz plus 6m version of the BPF board is still needing testing before shipping production kits.)

Theory of Operation

Project Schematic

(Resistor testpoints (hairpin, top, or left-hand lead) are marked with red dots)

Project Bill of Materials

See Project Bill of Materials

Project Expert's (terse) Build Notes

Board Top

Board Bottom

• Install all SMT and SOIC components to the bottom of the board, then the top of the board
• Wind and install the transformers
• Wind and install the Coils
• Install the ceramic capacitors
• Install the resistors
• Install the jumpers and connectors

Project Detailed Build Notes

For the non-expert builders among us, this site takes you through a stage-by-stage build of the kit. Each stage is self-contained and outlines the steps to build and test the stage. This ensures that you will have a much better chance of success once you reach the last step, since you will have successfully built and tested each preceding stage before moving on to the next stage.

Each stage is listed below, in build order, and you can link to it by clicking on its name below (or in the header and/or footer of each web page).

• Inventory the Bill of Materials
• Build and Test the Busses and Rails Stage
• Build and Test the Switches Stage
• Build and Test the Transformers Stage
• Build and Test the Band 1: 1.8-4 MHz Stage
• Build and Test the Band 2: 4-8 MHz Stage
• Build and Test the Band 3: 8-16 MHz Stage
• Build and Test the Band 4: 16-30 MHz Stage

Background Info

Tools

Winding Inductors

To learn how to wind coils and transformers, please read the

• tips from the experts and then
• view the excellent videos on KC0WOXs Website
• or take a read of Dinesh's VU2FD guidelines.

Soldering

• Read the Primer on SMT Soldering at the Sparkfun site.  It is a very good read and it speaks great truths.  Then take the time to watch the video tutorial on soldering an SOIC SMD IC.
• Solder Stations. Don't skimp here. Soldering deficiencies account for 80 percent of the problems surfaced in troubleshooting. It is preferable to have an ESD-safe station, with a grounded tip. A couple of good stations that are relatively inexpensive are:
  • 
    Velleman VTSS5U 50W Solder Station (approx $20 at Frys)
  • 
    Harbor Freight ESD Solder Station (under $50) 

ESD Protection

• Avoid carpets in cool, dry areas.
• Leave PC cards and memory modules in their anti-static packaging until ready to be installed.
• Dissipate static electricity before handling any system components (PC cards, memory modules) by touching a grounded metal object, such as the system unit unpainted metal chassis.
• If possible, use antistatic devices, such as wrist straps and antistatic mats (see Radio Shack's Set for $25 or the JameCo AntiStatic mat for $15)).
• Always hold a PC card or memory module by its edges. Avoid touching the contacts and components on the memory module.
• Before removing chips from insulator, put on the wrist strap connected to the ESD mat. All work with CMOS chips should be done with the wrist strap on.
• As an added precaution before first touching a chip, you should touch a finger to a grounded metal surface.
• If using a DMM, its outside should be in contact with the ground of the ESD mat, and both leads shorted to this ground before use.
• See the review of ESD Precautions at this link.

Work Area

• You will need a well-lit work area and a minimum of 3X magnification (the author uses a cheap magnifying fluorescent light with a 3X lens. This is supplemented by a hand-held 10 X loupe - with light - for close-in inspection of solder joints and SMT installation.
• You should use a cookie sheet or baking pan (with four sides raised approximately a half an inch) for your actual work space. It is highly recommended for building on top of in order to catch stray parts, especially the tiny SMT chips which, once they are launched by an errant tweezer squeeze, are nigh on impossible to find if they are not caught on the cookie sheet.

Misc Tools

• It is most important to solidly clamp the PCB in a holder when soldering. A "third-hand" (e.g., Panavise or the Hendricks kits PCB Vise) can hold your board while soldering.   In a pinch, you can get by with a simple third-hand, alligator clip vise. Jan G0BBL suggests "A very cheap way is to screw a Large Document Clip to a woodblock which will clamp the side of a PCB."
• Magnifying Head Strap
• Tweezers (bent tip is preferable).
• A toothpick and some beeswax - these can be used to pickup SMT devices and hold them steady while soldering.
• Diagonal side cutters.
• Small, rounded jaw needle-nose pliers.
• Set of jewelers' screwdrivers
• An Exacto knife.
• Fine-grit emery paper.

Project Completed Stage

Top of the Board

Bottom of the Board

Project Testing

Each stage will have a "Testing" Section, outlining one or more tests that, when successfully completed, provide you with the confidence and assurance that you are heading in the right direction towards a fully tested and built transceiver.  

When you perform a test, you should always record the results of the test where indicated in the Testing section. This will make troubleshooting via the reflector much easier, since you will be communicating with the experts using a standard testing and measurement regime.

This kit can be built and reliably tested using nothing more than a common multimeter. Tests assume that the builder has a decent digital multimeter of sufficiently high input impedance as to minimize circuit loading issues.  Measurements will be taken of current draws, test point voltages, and resistances.