TuneAid
After constructing the KN-Q7 kitset 40m QRP single sideband (SSB) transceiver, a matching low-power "Z-match" antenna tuner and a sensitive SWR meter were built. Tuning this setup required significant manual coordination. One hand was needed to hold the PTT button, while two hands were necessary to adjust the antenna tuner controls and whistle into the microphone to generate the required audio tone for RF power. This RF power enabled the SWR meter to assess the matching between the transmitter and antenna, indicating when the antenna tuner was properly adjusted. Complicating the situation was a cold that diminished the ability to produce a sufficient whistle tone. To address this, an external tone oscillator, known as TuneAid, was developed. The TuneAid is a discrete parts design utilizing common small-signal audio PNP and NPN transistors. The circuit operates by pressing pushbutton SW1, which activates Q1 and subsequently the oscillator (Q3 and Q4). Initially, with capacitor C1 discharged, Q2 is activated, keeping Q1 on after releasing SW1. C1 charges slowly through resistor R4, reducing the voltage on Q2's base until Q2 turns off after approximately 10 seconds, which in turn deactivates Q1 and the oscillator. Diode D1 ensures rapid discharge of C1 for the next cycle, maintaining minimal battery drain in standby mode for prolonged battery life. The Q3/Q4 audio oscillator, commonly used in Morse code practice oscillators, drives a small 8-ohm speaker that produces a loud tone, placed near the transceiver microphone during tuning. The prototype was housed in a compact plastic box, accommodating the PCB, speaker, and a 9V battery. The speaker used was a flat 25mm diameter type salvaged from an old cordless phone, although any 8-ohm speaker is suitable. All components are widely available, with transistors like BC548 (NPN) or BC559 (PNP) being appropriate. Capacitor C2 can be a mylar or disc ceramic type. The pushbutton used has a built-in blue LED for visual indication during operation, though a more economical alternative can be utilized. While the tuning process still requires multiple hands, the whistle issue has been resolved, allowing for a 10-second tone burst from the TuneAid, sufficient for managing the tuner and PTT key.
The circuit design of the TuneAid oscillator is straightforward yet effective, making it a valuable addition to the KN-Q7 transceiver setup. The use of discrete components ensures reliability and ease of replacement. The timer function, facilitated by the charging and discharging of C1, allows the user to focus on tuning without the need for continuous manual input. The audio oscillator's design, based on low-component count configurations, provides a robust tone generation suitable for SSB operation, enhancing the functionality of the transceiver.
The housing design, while compact, allows for efficient integration of all components, ensuring that the device remains portable and user-friendly. The choice of speaker, while flexible, is critical in achieving the desired output volume, which is essential for effective operation during the tuning process. The inclusion of a visual indicator through the LED adds a layer of user feedback, enhancing the overall usability of the circuit.
In summary, the TuneAid oscillator serves as an effective solution for overcoming the challenges associated with operating the KN-Q7 transceiver, facilitating a smoother tuning experience and ensuring that operators can maintain optimal performance without the need for additional physical capabilities.After I built my KN-Q7 kitset 40m QRP single sideband (SSB) transceiver, described elsewhere on this site, I went on to build a matching low power "Z-match" antenna tuner and a sensitive SWR meter. For some reason, I found I needed three hands to tune this apparently simple arrangement One hand to hold the PTT button down, and then two more ha
nds to simultaneously adjust the controls on my antenna tuner, while simultaneously whistling into the microphone, after delivering the essential voice station identification, of course! For those new to ham radio, an audio tone or a reasonably continuous level of speech is required into the microphone so an SSB transmitter will generate some RF power.
That RF power allows the SWR meter to measure the match between transmitter and antenna, and determine when the antenna tuner is correctly adjusted. My problem didn`t stop with the lack of three hands. A really bad cold had left me with a decided lack of "whistle-power". Those who suffer from asthma can probably appreciate this latter problem all too well. Adding a tone oscillator into the KN-Q7 QRP transceiver would have solved the problem, but space inside that radio is very limited.
This external TuneAid oscillator was my solution. The TuneAid is a simple combination of a timer and audio tone oscillator. It`s a 100% discrete parts design, built with common small signal audio PNP and NPN transistors. The circuit diagram is shown in Figure 1. Pressing pushbutton SW1 turns on Q1. This then turns on the oscillator (Q3 and Q4). With C1 initially discharged, Q2 is turned hard on, keeping Q1 turned on after pushbutton SW1 is released. So, only a brief press of the power-on switch is required to start the tone generator. C1 slowly charges through R4, steadily reducing the voltage on the base of Q2. After about 10 seconds, Q2 turns off, turning Q1 off, and of course, this then turns off the oscillator.
Diode D1 ensures C1 is rapidly discharged for the next time around. Battery drain in this standby state is minimal, ensuring excellent battery life. The Q3/Q4 low component count audio oscillator is an arrangement often used for morse code practice oscillators. A small 8 ohm speaker generates a surprisingly loud tone level, and this is held close to the transceiver microphone during the tuning process.
The prototype was built into a small plastic box just large enough to hold the PCB, speaker and 9V battery. I used one similar to Jaycar`s part number HB-6015. I milled out the speaker slots on the box cover to match the speaker. The speaker was a flat 25mm diameter type recycled from an old cordless phone, but any 8 ohm speaker, large or small, will work fine.
All other components are readily available from the usual sources, the transistors being any small signal types such as a BC548 (NPN) or BC559 (PNP). C2 is a mylar capacitor, but a disc ceramic type will work perfectly well in this circuit. My pushbutton ( Jaycar part number SP-0622) has a bright blue LED built in, and it looks great while the TuneAid is operating.
However, this is a relatively expensive part to use for such a simple switch. Feel free to substitute any cheap pushbutton you can find. While I still need three hands to manage the tuning process, I don`t have the whistle problem any more. A quick press of the TuneAid button will give me a 10 second tone burst, easily long enough to manage the tuner, and the PTT key.
🔗 External reference
The circuit design of the TuneAid oscillator is straightforward yet effective, making it a valuable addition to the KN-Q7 transceiver setup. The use of discrete components ensures reliability and ease of replacement. The timer function, facilitated by the charging and discharging of C1, allows the user to focus on tuning without the need for continuous manual input. The audio oscillator's design, based on low-component count configurations, provides a robust tone generation suitable for SSB operation, enhancing the functionality of the transceiver.
The housing design, while compact, allows for efficient integration of all components, ensuring that the device remains portable and user-friendly. The choice of speaker, while flexible, is critical in achieving the desired output volume, which is essential for effective operation during the tuning process. The inclusion of a visual indicator through the LED adds a layer of user feedback, enhancing the overall usability of the circuit.
In summary, the TuneAid oscillator serves as an effective solution for overcoming the challenges associated with operating the KN-Q7 transceiver, facilitating a smoother tuning experience and ensuring that operators can maintain optimal performance without the need for additional physical capabilities.After I built my KN-Q7 kitset 40m QRP single sideband (SSB) transceiver, described elsewhere on this site, I went on to build a matching low power "Z-match" antenna tuner and a sensitive SWR meter. For some reason, I found I needed three hands to tune this apparently simple arrangement One hand to hold the PTT button down, and then two more ha
nds to simultaneously adjust the controls on my antenna tuner, while simultaneously whistling into the microphone, after delivering the essential voice station identification, of course! For those new to ham radio, an audio tone or a reasonably continuous level of speech is required into the microphone so an SSB transmitter will generate some RF power.
That RF power allows the SWR meter to measure the match between transmitter and antenna, and determine when the antenna tuner is correctly adjusted. My problem didn`t stop with the lack of three hands. A really bad cold had left me with a decided lack of "whistle-power". Those who suffer from asthma can probably appreciate this latter problem all too well. Adding a tone oscillator into the KN-Q7 QRP transceiver would have solved the problem, but space inside that radio is very limited.
This external TuneAid oscillator was my solution. The TuneAid is a simple combination of a timer and audio tone oscillator. It`s a 100% discrete parts design, built with common small signal audio PNP and NPN transistors. The circuit diagram is shown in Figure 1. Pressing pushbutton SW1 turns on Q1. This then turns on the oscillator (Q3 and Q4). With C1 initially discharged, Q2 is turned hard on, keeping Q1 turned on after pushbutton SW1 is released. So, only a brief press of the power-on switch is required to start the tone generator. C1 slowly charges through R4, steadily reducing the voltage on the base of Q2. After about 10 seconds, Q2 turns off, turning Q1 off, and of course, this then turns off the oscillator.
Diode D1 ensures C1 is rapidly discharged for the next time around. Battery drain in this standby state is minimal, ensuring excellent battery life. The Q3/Q4 low component count audio oscillator is an arrangement often used for morse code practice oscillators. A small 8 ohm speaker generates a surprisingly loud tone level, and this is held close to the transceiver microphone during the tuning process.
The prototype was built into a small plastic box just large enough to hold the PCB, speaker and 9V battery. I used one similar to Jaycar`s part number HB-6015. I milled out the speaker slots on the box cover to match the speaker. The speaker was a flat 25mm diameter type recycled from an old cordless phone, but any 8 ohm speaker, large or small, will work fine.
All other components are readily available from the usual sources, the transistors being any small signal types such as a BC548 (NPN) or BC559 (PNP). C2 is a mylar capacitor, but a disc ceramic type will work perfectly well in this circuit. My pushbutton ( Jaycar part number SP-0622) has a bright blue LED built in, and it looks great while the TuneAid is operating.
However, this is a relatively expensive part to use for such a simple switch. Feel free to substitute any cheap pushbutton you can find. While I still need three hands to manage the tuning process, I don`t have the whistle problem any more. A quick press of the TuneAid button will give me a 10 second tone burst, easily long enough to manage the tuner, and the PTT key.
🔗 External reference