Wednesday, September 9, 2015

Simpleceiver ~ A 40M SSB/CW Receiver and Test Bed Updated with Si5351 vs LC Oscillator

Another Short Diversion from the New Antenna Build

 
For the last week or so the temperatures in southern California have been inching toward 100 Degrees F. It is just too hot to work outdoors and the next step involves assembling the 2 element Tri-Band beam which of course would be done outdoors. So I have taken a short break from the antenna installation to work on a radio project in hopes that the temperatures get back into the 80's.

So now the temperatures are down But believe it or not is raining --we direly need the rain. But there is so much junk in my garage that the beam can only be assembled out doors so back to the Simpleceiver while I wait for the weather to clear
 
 
In the back of my mind I have been thinking about building a simple super-heterodyne receiver that could be easily replicated, has a low part count yet some nice features like a 3 pole crystal filter. In searching my junk box I found some 12.096 MHz crystals which if used with a 5.0 MHz LO would put you on 40 Meters. Another design goal was small (like to take it portable) so some of the circuitry would be surface mount. I have tried several LO's with the receiver including an LC oscillator, a varactor tuned NE602 configured as an oscillator followed by a MMIC RF amp stage and finally the Si5351 using only the Clock 0 output. Below is a Block Diagram of what I call the "Simpleceiver".
 
 
 

 
The upper photo shows the Simpleceiver with the NE602 Oscillator and the lower one with the VFO.  A future evaluation will be to switch between the LC VFO and the Si5351.
 
Unfortunately some well respected members of the homebrew Illuminati community have panned the Si5351 claiming that such devices when used in home brew radios are totally unsuitable arising from the Si5351 phase noise signature. My experience has been entirely different.

I added the second LO where you can switch between the LC VFO and the Si5351. I sure couldn't tell any difference.There will be a new direction for this Simpleceiver which you will hear more about in the future. I am impressed with how well it works with such few parts.
 
 
73's
Pete N6QW
 
 
 
 
 
 
 

 

 

7 comments:

  1. bravo Pete ,very very nice presentation....i also use si5351 in "lets building something 2" and "Belthorn" and works very good...and also in "ZIA" i will see......for homebrewers and for radio amaters is quite ok .9a3xz

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  2. and very important for me.....for 20 dollars (shiping to Croatia ) 4$ ARDUINO NANO i 16$ si5351 i have very stable BFO and VFO.

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  4. Hello Pete, I have a question: why do you mix at 5ish MHz VFO with the Si5351 and not on the upper side, that is, 19ish MHz? The Si5351 is perfectly capable and with no unstability, I guess... The spurious and birdies should be researched in both cases, though...

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  5. Anyway 4.8 to 5.2MHz VFO is a nice frequency for a standard analogic "old style" VFO with no much drifiting if built with care...

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  6. Hi Pete, I like reading about your accomplishment in amateur radio building qrp radios and I have been tempted to try and build some your of rigs. The block diagrams are great and gives a nice overview, but without a lot detail about the circuit. I like both the block and a schematic. I do prefer a schematic to allow me to know what to build and to understand more about the circuit. I probably have not looked hard enough to fine the schematic for the simple receive. I will continue looking. I like the small display you have been using in some of your projects. My hope to master and under stand the circuits and code involved. Now I got to go and listen to the latest solder smoke. 73's John . kg9dk

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  7. Hi John,

    Thanks for your posting. This particular post is only one of about 20 on the Simpleceiver and was early on in the project. So you will need to read the later posts. These later posts should be right up your alley as there is extensive use of LT Spice to simulate the various circuit blocks in the radio. The postings include simulation plots of circuit performance so you can actually see what the circuit will do. This particular post was an initial proof of concept. There are circuit schematic details (ala LT Spice Schematics) of the RF amp Stage, Band Pass Filter Stage, IF amp Stages, Product Detector. and so on. A lot of attention was paid to impedance matching between the circuits and that has played a major part in the overall success. Go to you tube and search on N6QW Simpleciever and you will see and hear a video of the later version and you get a good tour of all of the modules.

    Thanks again for listening.

    73's
    Pete N6QW

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