ad9850ddsham-radioradioRF
I've built WSPR transmitter based on AD9850.
AD9850 is driven by 125 MHz crystal. TX frequency is 14 Mhz.
On the receive side there is upconverter (+125 MHZ crystal) and SDR (both RTL-SDR and AirSpy). Both SDRs show the same 100Hz spurious emissions.
What is the source of these emissions? Is it coming from upconverter or from AD9850?
Try these linear amplifiers made by Apex. They are designed specifically for ultrasound aplications.
A lot of questions but if you are looking for a WWV receiver design here is one and below is one of the circuits contained on the link: -
YES but it's probably not too critical if you are receiving a decent signal. A quarter wave dipole at 10MHz is optimum but this will be 7.5m long so try a couple of metres.
NO, you need to tailor the inductance capacitance ratio to give a decent Q factor but not be susceptible to parasitic components. Try for a resonant circuit that uses no less than 50pF - 50pF and 5060nH resonate at 10MHz - if you half C, double L for same resonance at an improvement in Q of 2:1. BTW it's "M" not "m" in MHz
Tricky, suck it and see
See design linked to for best guess at what you should be aiming for.
WWV uses up to 100% modulated AM (or normal DSB) transmission. Use a diode detector (as per link) to produce the demodulated waveforms.
Best Answer
100Hz or 120Hz noise is often caused by power-supply ripples or rectifier glitches. those being twice the mains frequency in different locations.