Farhan's Direct Conversion Receiver

Thank God for the Wayback machine.  For a moment I feared that this article about Farhan's DC-40 receiver had been lost.  (Phonestack is now some Vietnamese vendor. ) But the WayBack Machine archive came through for us.  

https://web.archive.org/web/20171109081542/http://www.phonestack.com/farhan/dc40.html

Farhan's receiver has been covered on this blog before, but it is especially relevant for us now that we are immersed in our own direct conversion receiver project.  Farhan was working with his niece, who was a student.  We are working with high school students. 

I really like Farhan's blow-by-blow description of the build.  There are raw emotions here: He speaks of his hatred of LM-386s, and of how he thought of using the copper clad board as a projectile.  His niece wonders about the possibility of evil spirits in the receiver. The battle against AM breakthrough is very familiar.  (I like the RF choke idea.) You won't find candor like this in QST or QEX.  

Farhan's DC-40 project was one of the inspirations for our high school effort.  In fact, when we first went to the school, I left behind a direct conversion receiver that I had built.  Taped onto the bottom of the receiver was a quote from the DC-40 article and a picture of the Wizard of Hyderabad.  (See above, and click on the picture for a better look). 

This week we will inject some more Farhan-ismo into our receiver.  The time has come to build the mixer.  Like Farhan, we will go with the diode ring.   Winding the transformers would be very time consuming.   I remembered that on his visit, Farhan had left me a box of trifilar toroids wound by the seamstresses of Hyderabad using FT37-43 cores.  We will uses these in our build.  They will add a lot of soul to the new machine.