G K Chesterton was a British author and if you follow British Detective stories his book on Father Brown (Part time Priest and part time Detective) is the basis of the very popular Brit TV series "Father Brown".
While in college a literature assignment was to read one of his short stories entitled "What I found in my pocket".
"What I Found in My Pocket" is a short story by G.K. Chesterton that humorously explores the theme of finding unexpected treasures in one's own pocket. The story begins with the narrator recalling a moment of curiosity and excitement during a long train journey, where he finds various items, including a pocketknife, matches, and a box of matches, all of which he finds amusing and surprising. The narrative reflects on the narrator's state of innocence and the reverent ignorance he has about the contents of his pockets, suggesting a playful and whimsical exploration of life's small joys and the unexpected treasures we often find in everyday situations.
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Using that Chesterton short story as a grounding basis, today, I looked in my Junk Box to see what I could find. I closed my eyes and thrust my hand into the box and what resulted with a grab was two assemblies.
One assembly was a homebrew double balanced mixer stage that was formerly installed in the LBS transceiver that dates back over 10 years ago. Yes, I have homebrewed DBM's and this one even has balance controls (phase and amplitude) like what is seen in EMRFD under my old call W6JFR. It also sports a pi network audio filter as its original use was as a product detector and balanced modulator. One other slick feature was the ability to "unbalance the DBM" with a simple grounding of a small value resistor. (Maybe our 8-day wonder Ham Radio Rock Star knows this.) But this is an OT method of producing a TUNE signal. Note the use on the W1REX MePads.
The second is a Digital LO that used an Uno R3 clone and a AD9850 which pre-dates the Si5351. The AD9850 fell out of favor since it cannot simultaneously produce the LO AND BFO signals like what can be done with the Si5351.
So now the question before the court what could be done with these two assemblies. This is almost like the Thanksgiving the XYL (SK) and I were invited to a friend's house for dinner. We did not know that the main course was not a Turkey, but a Tofurkey
which is of course a Tofu based meat substitute. I zoned out during the meal and sat there thinking how many words you could make from Tofurkey. The obvious are fur and key then there is for and fork and toy. Rot was especially appealing.
Immediately I thought the two assemblies could be the main elements of a Direct Conversion Receiver... the Detector and LO. A couple of more bits could make that happen like a BPF (there were some in the Junk Box) and an Audio Amp which also were a part of the Junk Box stash. Chesterton were he alive (SK 1936) would be smiling.
But there are lots of DCR's floating around including my MC1496 based design so what else could be done with the Junk Box find.
If we set the AD9850 via a simple toggle switch to either 8.998500 or 9.001500 MHz, drop the LCD and add a single 2N3904 mic amp stage, we have the early stages of a SSB Transmitter. We of course would then need a 9MHz SSB Filter which I find can be had cheaply on eBay about $10 plus shipping. Why homebrew this filter as you have already homebrewed filters, so it is not a learning experience. Yeah, I know you have to dust off the Nano VNA to justify that purchase, but the time economics say buy this one
Or, if we remove the audio filter it could be a frequency mixer conversion stage such as you might have in a dual conversion receiver.
Keeping with the frequency conversion approach let's turn these two into a CW transmitter with frequency agility.
We will need to build a single stage one transistor 2N3904 Oscillator operating at 5 MHz we then set the AD9850 to operate in the range of 12MHz to 12.125 MHz which with a subtractive mix would yield an output of 7 to 7.125 MHz. We would need to follow our mixer stage with a Band Pass Filter, and those 2 frequency ranges look OK for any unwanted mixing products.
If you spent the $30 Amazon Christmas Gift Certificate on that ATS20 receiver you are getting close to having a 40M CW station. A problem if you let the Oscillator and AD9850 run continuously... you will hear it in the receiver when receiving.
So, a simple 2N2905 PNP transistor can key the 2N3904 crystal oscillator and with some shaping of the keying will have a nice sounding signal. You will need to follow the BPF with a 2N2219A driver and a IRF510 final (and a W3NQN LPF) and you are there. If you check this link you can find sample circuits that will work, following the BPF.
Sure, there are some bits left out like TR and module interconnects. But if you got an Extra in 8 days you surely have that knowledge.
So, check your junk box and you might be surprised what you find in your junk box. BTW those packets of Trojans can protect your fingers while soldering.
Them that know can make things go. If you check history more interventions in South American and World politics occurred under Republican presidents. Funny how the focus seems to be bananas, oil and/or other natural resources.
73's
Pete N6QW