Construction projects
The club holds construction evenings as part of its regular activities. Here are details of some of the previous projects built. For further details please contact a member of the committee.
End Fed Half Wave antenna – unun matching transformers (2023)
This project offered a 10w QRP option using a 2643625002 type 43 ferrite core and a 100w-capable option using a 2643251002 type 43 core. Both came with required 100pF capacitors. Full instructions for winding the transformers and a number of options for antenna configuration are in the downloadable pdf file, along with background information and links to various papers and online resources.
Pixie QRP CW transceiver (2019)
Pixies are very simple, very basic and very small 40m CW transceivers with two transistors and one IC. They were built from kits bought on eBay from a UK supplier. The kits came with crystals for 7.023 Mhz but we also offered crystals for the QRP frequency, 7.03 MHz.
BBRC StationBox (2018)
The BBRC StationBox was a GPS-enabled UTC clock, thermometer, barometer and locator display. It was based on a ‘ShackBox’ design from a PW article which was created and coded by Martin Waller, G0PJO. PCBs were designed by Tony G8TDL and software further wrangled by Colin G8RLZ. Full information including Arduino code is available to club members on a shared Dropbox folder. As of May 2021 we still have a few PCBs but few other parts available.
Multiband linked dipole (Oct 2016)
These antennas were constructed using a kit of parts from SOTAbeams, along with some wire acquired separately. Full details are on the Sotabeams website.
1:1 or 4:1 toroidal HF balun
The circuit diagram and construction notes are available on the link below Refer to the diagrams for general construction information. The balun was constructed using a T200-2 (red) iron powder toroid.
Frequency counter (2009)
0 to 60Mhz frequency meter/counter based on a PIC, developed by Jeremy, G8MLK
The Burnham Beeches Radio Club frequency counter is a PIC micro controller based frequency counter with LCD readout. It can be used stand alone or the in built offsets allow integration into a receiver. Born out of a BBRC construction evening, it was adapted from an original design by EI9GQ published in the RSGB’s monthly magazine Radcom. Jeremy G8MLK was kind enough rewrite the code, engineer, source and produce the kits for the project which was completed by the majority of club members in an evening. Details, as well as the source code for the PIC controller can be found here: http://www.burnhambeechesradioclub.org.uk/archives/the-bbrc-frequency-counter-2009/
HF Receive Noise Canceller
This is based on a PW design which uses 2 antennas: a main antenna and a “noise antenna” where the device cancels out the noise leaving a clearer receive signal.
Component Tester
This was one of our most successful projects. The testers can be used to test resistors, capacitors, inductance, transistors, diodes, FETs etc. Many members still use their testers on a regular basis. They were constructed Chinese-made kits bought on eBay. Although the kits are no longer available there are newer designs available that include a lever-operated ZIF socket to hold the components.
PSK31 Transmit Power Regulator
Rig to PC interface. This box enables the rig to be connected to your PC but effectively isolates each from unwanted voltages. It has an RS232 output plus audio. Isolation is by way of transformers and optical isolators.
Softrock SDR Receiver
This is a basic SDR for one band built from a commercial kit. It relies on connection to a computer soundcard with SDR software running on the computer. Documentation is available at http://www.wb5rvz.org
Similar kits are still available at http://fivedash.com/
Isolated Sound Card Interface
Transformer isolated audio and opto isolated CAT interface
80/40 M loop amplified receive antenna
This is a PW design for a 60 cm diameter receive only loop antenna for DF or tracking of QRM etc.
40 dB Tap
This is an RF “sniffer” which enables you to sample a signal at 40dB reduction for power checking or signal sampling etc, built into a diecast box with N-type in and out connection and a BNC -40dB output connection. Based on a design in the June 2001 edition of ARRL QST magazine, which also features in the ARRL Handbook.
2M Tape Measure Yagi
This is a fold-up 3 element yagi for mainly direction finding/fox hunt use with a switched attenuator (resistive) to mount on the antenna. The original reflector length was incorrect but the pdf download has handwritten corrections.
2 Metre Slim Jim antenna
Made from 450 or 300 Ohm ladder line. A simple and very cheap 2m vertically polarised antenna useful for travelling.
