Posts

Showing posts from August, 2020

New Technology for 2020 ~ A Direct Conversion Receiver You Can Build

Image
Some Arduino Code as used with the Left Coast Loafer CW Transmitter.//Turn ON:     si5351.clock_enable(SI5351_CLK1, 1); //Turn OFF:   si5351.clock_enable(SI5351_CLK1, 0);
/*OK you missed it -- the "1" turns it on and the "0" turns it off.)
So my code senses if Pin 4 is LOW and if so then turn ON the CLK1. If it is not LOW then turn it OFF. This is the standard If Else regime. You also have to blank out the frequency in the else part of the code. Here is the code*/
 void CheckCW() {

                 digitalRead(4);                  if(digitalRead(4) == LOW){                  si5351.clock_enable(SI5351_CLK1, 1);

                 si5351.set_freq( rx1 - 700, 0, SI5351_CLK1);


         }
            else{
si5351.clock_enable(SI5351_CLK1, 0);
}
}

I plan on a MOX operation where you flip a switch and that turns on CLK1 and at the same time does the TR. There is embedded code to produce a pulsed 1kHz Tone for tune up. 

No reason with a little code rework that this 988Hz Tone would be the …

New Technology for 2020 ~ Tripping Back in Time to Earlier Advanced Technology

Image
Reflecting Back In Time...[N2CQR, Bill, reminded me that Direct Conversion Receivers were embedded in commercial product offerings such  as the famous Heathkit HW-7 and HW-8. I also think one or two Ten Tec Rigs may also have employed that same DCR technology. I seem to recall The Century 21 as being one. But i might have that wrong. Elementary bare bones rigs like the PIXIE are in reality crystal controlled DCR's. 
KK7B published an article on a phasing receiver that at the heart uses two DCR's and shows a technique for eliminating one of the sidebands.
There are of course many published articles from sources like the GQRP SPRAT and QQ that have documented such DCR projects. Below from Winter 2012 QQ is a FB article from the prolific and world renown author N6QW. Too bad it used an Analog LO which is a real detractor to this project.]




The prior photos that were posted in this run highlight and focus on the "artful" nature of those homebrew rigs. Skill was needed to ble…

New Technology for 2020 ~ What should you believe?

Image
Baffled by What I See!August 16, 2020
I started this by asking what should you believe and one blog reader suggested I look at a couple of plots that measured the V out divided by the V in. This measure tells much about your circuit but has left me with some yet more questions about what to believe. My earlier plots looked only at output form the circuit not a measure of how the circuit responds (V out) in comparison to the input (V in).
So I did that (interesting results):
Wow the ratio of the output to the input is FLAT and the V in appears to be affected by circuit loading versus frequency. So this is not termination insensitive although the relative measure of the ratio is consistently flat. Now I ask the question that what really counts is what is coming out of the stage to drive the next stage looking only at the output. We next look at charts where we measure the Ratio, V out and V input.
There is close to  a 3db Drop in output at 10 Meters with the 100nF. Now we repeat with the 4.…