Re: BITX40, are these SA traces as they should be? #bitx40help
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On Sunday, March 18, 2018 1:41 PM, "news1@..." <news1@...> wrote:
Built my Bitx40, mostly to learn more about troubleshooting radios. I know a bit about measuring and how things "work" but just from reading theory. Practice is clearly different, and a good way to actually get some understanding.
As a result, my setup and measurements may be flawed from the beginning, though I try to do things the "right" way.
As I didn't receive much when trying to listen to the Bitx40 on my TS-870, I started looking at the schematic and trying to figure out what was going on.
Bitx40 through 20dB attenuator into a SA. VFO/DDS frequency set at 7110 kHz, no modulation into the microphone (shorted the pins) except for the screenshot with the 10kHz span.
In the 2MHz span, note the strongest peak is at -12dBm around 7333 kHz.
There's another peak around -18dBm at 7110 kHz (which I suppose is the DDS)
Another peak at 7555 kHz, about -41dBm.
In a 10MHz span, I see peaks at 14.218 kHz (-78dBm, obviously harmonic of DDS freq, right?) and 14.445 kHz (-68 dBm, no idea where this comes from).
I don't have a audio freq generator, will build one to inject a know signal into the mic input.
So, a couple of questions:
I might be missing something obvious, but have been looking a it for a couple of evenings now.