This is a really nice one. In the "proof of life" video we find a lot of proof, and a lot of life. SSB from the UK sounds really good. This is one of the beauties of the Direct Conversion architecture -- you end up with a receiver that sounds very good. Doug DeMaw said these receivers have "presence" -- it sounds like the other fellow is present in the room with you.
Dave's happiness and satisfaction really shines through in his comments. Dave writes:
I've just completed my DCR, and it's been an absolute blast!
I'm a retired EE, where PCBs and surface-mount components are the norm. I've occasionally prototyped using dead bug or Vero-board, but this is my first exposure to Manhattan construction - and I've thoroughly enjoyed it. Electronics and radio were my childhood passions, but inevitably, they lost some of their appeal once they became a career. Thank you, Bill and Dean, for helping me regain some of that lost joy!
My biggest challenge was trying to locate parts from a single UK source to minimize shipping costs (yes, I'm cheap). I briefly contemplated building a push-pull audio amp to avoid purchasing the transformer from Mouser, but in the end, I found most parts there, then padded the order with common junkbox parts to get free shipping. I'm so pleased that I heeded Bill and Dean's advice to build the receiver as presented (well, almost). The results are so much better than I expected, with great-sounding, room-filling audio when connected to the passive half of an old active stereo speaker pair. Tuning is a bit fiddly but improves with practice. Luckily, I had no problems with any of the stages, and it just worked when the boards finally came together.
To save money (did I mention that I'm cheap?), I decided to use NP0 capacitors in the PTO instead of silver mica. The thermal coefficient should be similar, and if they didn't work out, I planned to swap to mica later on. It turns out NP0 works great for me, with no noticeable drift after several minutes.
I don't have easy access to a 3D printer, so I decided to roll my own PTO former. I wound the coil on a Bic Biro with a layer of heat-shrink tubing to bring the diameter to 10mm. This was glued to a wooden support, and the M6 threaded brass bar was a perfect fit inside the Biro. I finished it off with a tuning knob made from an old RC aircraft prop spinner. After experimenting with coil spacing, I ended up with wide spacing under the actively tuned area of the coil and tight spacing at the other end. This reduced the tuning sensitivity, and I now get around 40 kHz per revolution.
I'd really like to make a home-brew 2-way contact with this receiver, so maybe I'll try a DSB transmitter next...
Thanks again to Bill and Dean for providing this fantastic resource. I've been a SolderSmoke listener since episode #1, and after 20 years of constructing radios vicariously, I've finally built one myself!
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FB Dave! Thanks and congratulations.
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