G0NQE Club Projects

Below is a selection of club projects designed and built by Colin G0NQE. Tuesday evenings were set aside for construction leaving Thursday as a general club night. 

GDO with built in Frequency Counter 

& Active Antenna Bridge

Acorn SDR

Colin had a small batch of boards made for PDARS members to build and the remainder were sold online. When complete the receiver covered two switched sections of the 80m phone band. Glenn Marsden bought one of the boards and he has produced a Youtube video showing it's construction. The rights were eventually sold and a commercial version was made available from Kanga UK where it was further developed into the Acorn II.

The Willow, a 40m Single Band Transceiver 

by Colin G0NQE and John G4LOS

Colin describes below how 'The Willow' came about; 

It was September 2003 and I was recovering from my first heart attack. I was at the club and feeling very bored, I said to John G4LOS why don't we build a single band transceiver. John being John said "what the hell for", I said we can design one for 40m, I can design and build the transmitter and you can design and build the receiver. He finally said yes and we got started. I called the transceiver, The Willow, a mixture of mine and John's surnames.

The transceiver worked very well and I used mine quite a lot at the time. It was all built in a modular fashion which made it great for a project. I asked if anyone would like to build the Willow and got 10 members who wanted to build one.

I made parts kits for every stage of the transceiver in dead bug style and members built each stage over about 8 weeks. We started with the receiver first, building the band-pass filter and first mixer, then carried on the week after with the next module and so on. The crystal filter consisted of six 10 Mhz crystals and the VFO was a huff & puff stabilised colpitts oscillator operating between 2.9 - 3.0 Mhz. Testing was done each week to make sure that stage was working before moving on to the next. 

We had a good time doing the Willow and 10 out of 10 worked. I still have the prototype I put together and I still use it from time to time on 40m.

Circuit Description

 The receiver was designed by John, G4LOS with a front end consisting of a three pole band pass filter and a J310 RF amplifier.

The inductors used for the band pass filter were 8.2uH axial chokes with a low impedance link winding wound over the middle of the choke at the input and output of the filter. This gave 50ohm in for the aerial and 50ohms out for the first mixer.

The two mixers used in the receiver were both home made ring diode mixers, accordingly the strong signal handling qualities of this receiver are excellent.

The output from the band pass filter is mixed with the VFO to give the 10Mhz IF Frequency.

Output from the mixer is then amplified using a 2N2222 broadband amplifier, the output of which is then transformer coupled to the 10Mhz six pole crystal ladder filter.

The filter crystals were 30p each from a well known emporium; we achieved a bandwidth of about 2.6Khz with this filter. Once the signal is filtered it is then amplified by the MC1350 IF amplifier chip with AGC facility.

The second ring diode mixer is used as the product detector; output from the MC1350 is mixed with the CIO to give us the required audio signal out from the mixer, it is then amplified by an audio pre amp consisting of two BC184 transistors, output from the audio pre amp is then fed into a BC546B.

The resulting amplified audio is then connected to the audio PA an LM386 and a small amount is fed back to the AGC amplifier.

John managed to get one FET a BS170 to do four jobs i.e. AGC detector, AGC amplifier, S meter driver, plus an IF gain control, not bad value for one FET and it works to great effect.

The output from the AGC amp is fed to pin 5 of the MC1350 and the resulting AGC action is quite smooth.

The last thing to mention is the CIO which consists of a single BC546B plus 10MHz crystal and a 60pf trimmer, the output is filtered by a low pass filter.

The whole receiver was made on two boards, one for the front end, first mixer and broadband amplifier. The other board consisted of the crystal filter, IF amp, product detector, AGC amp, CIO, audio preamp and PA.

The Willow was originally designed for 40 Metres but we have built different versions for other bands and it works just as well.