Intermediate

The Ivel plus Ilford CW TX

The Ilford transmitter (on the left above) allows you to send Morse code. It is normally coupled to a simple receiver like the Ivel receiver described on the Simple page. The Ilford transmitter can work on any one of the 20 to 80m bands and is ‘crystal’ controlled – this means that it uses either a crystal or a ceramic resonator to determine the transmitted frequency. For 80m, there is a suitable 3.58 MHz resonator whose operating frequency can be pulled down by a tuning capacitor to give a tuning range of typically a few 10s of KHz in the CW section of the band. Unfortunately, higher frequency resonators are not sufficiently stable and cannot be used above 80m, so you have to use an actual crystal for 20, 30 or 40m – the consequence is that the tuning range on these bands is very limited – a KHz or so! This means that 80m is often a good band to experiment and learn CW skills. The transmitter produces 1.5W of RF using a 13.8 volt supply and includes an output low pass filter to get rid of unwanted harmonics. It also includes a transmit receive relay for switching of your aerial between RX and TX, this is activated automatically when you press the key and has a delay before reverting to reception to cater for the gaps between Morse characters. Pressing the key also activates the RX muting electronic switch which prevents unwanted crashing sounds from the RX when transmitting, while still allowing the keyed 725 Hz sidetone oscillator to run and produce audio output through the RX’s audio output amplifier.

For 80m, the ceramic resonator can alternatively be fitted in the Ivel RX allowing transceiver operation where TX and RX operate on effectively the same frequency with single knob main tuning! In fact, the RX has to be tuned very slightly off (by the RX’s Fine control) in order to create a beat note but this offset is automatically removed by the Ilford when actually transmitting. This arrangement is a little more electrically complicated than separate RX and TX, but it does make operation very much easier! The kits in the picture above are wired this way for 80m. The standard Ilford kit includes the 3.58 MHz resonator but if you want crystals for the higher bands you need to tell me what is wanted. With a crystal in the Ilford for the higher bands, the tuning of the Ivel and Ilford are no longer linked and they have to be tuned and operated as ‘seperates’; so please ask me about crystals and adding a trimmer to the Ilford when contemplating this form of separate tuning and I will advise the costs. The standard Ilford kit costs £18. If ordered together, the Ivel and Ilford are discounted to £43.

The Ilton DSB Transmitter

This is a double sideband phone transmitter intended to go with the Ivel RX. Double sideband is much simpler and cheaper to produce than SSB and it is entirely compatible with stations using SSB – either upper or lower sideband. They wont know you are using DSB until you tell them! Much like the Ilford above, the Ilton needs to be crystal controlled except on 80m where there is a suitable 3.69 MHz resonator, which allows transceive operation with the Ivel on 80m. For the higher bands, they have to be tuned independently. Please ask me about these higher bands. The transmitter is mounted just behind the Ivel RX (see photo below) with links to the RX for muting when transmitting. The Ilton’s speech amplifier is designed for dynamic microphones and uses BS170 MOSFETs driving an SA602 modulator to produce the DSB signal; this is amplified using a high speed op-amp driving the IRF510 output stage (with heatsink) which is followed by low pass filters and the aerial change over relay. Peak output is about 1.5W when using 13.8v supplies.

Should be just the job for across town nattering! The price for the Ilton is £24, If ordered together, the Ivel and Ilton are discounted to £49.

The Somer

This is a new small CW TCVR for any single band 20 to 80m. It has a new LO scheme using multiplication up and division down from the VFO to avoid chirp without using a crystal or ceramic resonator! So goodbye to rockbound transmitters! The arrangement can provide whole band coverage but this is seldom actually desired to keep the Main tuning rate reasonable. The RX is direct conversion with a PolyVaricon for the main tuning and a voltage controlled diode for the Fine tuning and beat note offset; the latter being automatically cancelled when you go to transmit. The RX is direct conversion using a double tuned RF filter feeding into a SA602 mixer, with a conventional audio pre-amp, humped low pass CW filter and main audio output for phones or a small loud speaker. For transmission, the LO chain feeds digital gates for the RF keying which then drive a buffer stage and a pair of BS170 MOSFETs in the output stage for a nominal 1.5W (with a 13.8v supply). The transmitter output has twin pi low pass filtering and the TR control circuits automatically disconnect the LPF from the RX RF amp when transmitting, for click and thump-free full break in changeover! There is also a 725 Hz sidetone oscillator, with adjustable level, that feeds into the RX audio amp. The photo above is the 20m prototype Somer; two kind early builders have now helped prove the rig and the instructions! The main differences between the Somer when compared to the Ivel/Ilford combination is that it is half the size, with VFO coverage for any one of its bands and with full break in operation. The price is £52.

The Queenie & Kingston

They are a new pair of CW RX and TX. They are in the late stages of design, with the PCB layout done but not fully proven yet. The RX is a strong direct conversion design using 4066 switches. The TX produces 5W and has break-in transmit to receive change-over. Together, they use the same multiply up and divide down LO scheme as the new Somer, so they provide all of any single band from 20, 40, or 80m without using a crystal! They have a couple of optional add-on units – for phasing single sideband CW reception on a single band, or for three band operation. I am in the final stages of commissioning the prototypes. Watch this space!

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