Re: DSB transceiver for Digital mode
Ron,toggle quoted messageShow quoted text
SNR is 5-10 dB worse. However, I found that I only can make QSO with radios of -15dB SNR or better, so I think this is not a problem. Same as QRP communication, you have bigger chance to QSO with bigger signal. You may have interest to hear more signals even you don’t have chance to make QSO, but if I improve the SNR, I have to sacrifice RF output power to avoid self-oscillating. This is the limitation of using only one NE602 for TX and RX, and I chose to sacrifice RX performance to make the transceiver more balanced.
Heating is a complex question. It is documented that if the ambient temperature is around 50 C, the thermal drift of an AT cut crystal is minimal. Adding heating resistor is just to complete the heating progress in short time. There is just another way to help you if you really need help, especially on 20m band in which specific percentage of drift will cause bigger amount of drift in Hz. Also the heating power is only available during RX, so it is kind of compensation during RX.