At my second house, I have no way of listening to CW or SSB, unless I hook up my homebrew 20 meter SSB transceiver, or my FT-817 transceiver, so I’m thinking I might try to build a simple communications receiver to solve this perceived problem.
My first receiver build was a direct conversion (DC) receiver, that did not work very well, but motivated me to learn how to build better superheterodynes. I’ve attached a copy of the magazine article for that first receiver. So, I’m thinking I might have a try at another DC receiver. These seem to be the new state of the art as SDR receivers.
As with the general coverage broadcast receiver, commercial off the shelf parts will be used if there is an advantage to do so, and the cost is reasonable. My goal will be realized with a simple kitchen table receiver that works well for its intended purpose and can be used on a daily basis. A secondary goal is to make it a true kitchen table receiver, by doing all construction at my second house on the kitchen table, with no resort to any of the tools / equipment in my ham shack. A multi band receiver would be nice, but probably is not essential, at least at first.
I have an extra working QRP Labs VFO left over from the development of my 20 meter SSB transceiver, so it will probably be used for frequency synthesis, at least in the early stages of development, if not permanently.
This will be an experiment / work in progress sort of thing, sharing time with a couple of other projects I want to do. My simple SSB transceiver took three years to satisfactorily complete, and the simple general coverage broadcast receiver took another year after that, so those are the sort of time frames I operate in when tinkering / experimenting with stuff.
73,
Win W5JAG
Below are the spectrum displays of the two types of VFO's used here - the Si5351 LO and the AD 9850 DDS based LO.
The Si5351 is a square wave based device, so all the harmonics are normal, and expected. All of the scruff surrounding the harmonics is more problematic, as they are fairly high level in amplitude, and, worse, move around, disappear, get generated at new frequencies, etc., while the device is being tuned.
With the DC receiver, this is really audible as the device is tuned, The device is much easier to tune with the DDS based LO. It also sounds less noisy to me with the DDS, although I do not have the capability to measure that.
Once the receiver is set to frequency, the difference is not too apparent. I probably would not build another DC receiver using an Si5351 based LO unless i intended to park it on a fixed frequency.
Win W5JAG