Will's homebrew station is really something. The rig (it truly qualifies for this term of praise) is amazing all by itself (see below), but a look at Will's QRZ page reveals other ingenious inventions and techniques: There is the clock made from panel meters. And the method he uses for making aluminum project boxes. He even made an N0WVA regen receiver. That's the one I used in my ET-2. Fantastic.
Will really needs to share his homebrew skills with others. I hope he is soon in a local high school teaching students how to build things. Thanks Will!
Bill and Pete,
Just wanted to send a note to update you on the latest projects here. The last time I emailed, I mentioned wanting to build a superhet, which you (rightfully) discouraged, pushing for a DC receiver.
Well, I finished the superhet at the end of last year. I had most of the receiver working long before then, but got bogged down in an AGC system. The final receiver is a 5 band si5351a controlled single conversion superhet loosely based on Todd, VE7BPO's design with several modifications. I used a 9 Mhz IF instead of 4, I used a digitally controlled LO and BFO, and as mentioned, I added an AGC system, which ended up being the most challenging (and most interesting) part. The final AGC system I ended up with used the detector and amplifier side of Wes Hayward's "full hang" AGC from SSDRA, but I didn't have the IC IF amplifiers with variable gain, so instead, it fed a PIN diode attenuator circuit to control the IF gain. The final result worked great, but I nearly pulled my hair out getting it to work. I originally intended to build the receiver for 40 and 20 meters, but it ended up covering 80, 40, 30, 20, and 15 since I used the filter relay board from QRP Labs which had 5 slots.
After I got the receiver running, I decided I needed a matching transmitter, so I built up a simple CW transmitter to match. It uses an si5351a VFO driving a 74HC04 hex inverter as the buffer amplifier. The trick here is that by driving all the inverter gates in parallel, the output impedance is ~14 ohms broadband, suitable for driving a BJT PA without any need for matching transformers. The PA is 3 2N2222s in parallel with heat syncs putting out about 2 watts from 80 - 15.
The part I'm most proud of is that I have the arduino for the receiver connected to the arduino for the transmitter through a serial line. The receiver sends it's current frequency to the transmitter so that the transmitter can track the receiver's frequency as you tune (like a transceiver). I'll attach a few pictures of my homebrew station below. The transmitter is on the left, receiver is on the right. The box on top of the transmitter is my homebrew keyer. Next up on my build list is a solid state T/R switch.
Bill, I've enjoyed following the updates on the school DC receiver build. My local club is wanting to do some youth outreach, and I'd love to get them involved in building. I'm the only builder in the club though, so I don't know if I personally have the manpower to make it happen. Also, thanks for the recent info and pictures of Cuban homebrew rigs. I grew up listening to Arnie Corro, so I love seeing their resourcefulness and ingenuity. Makes me want to take apart some old electronics.
Pete, I'm enjoying following the 10M SSB project. With the uptick in propagation, I've been bitten by the 10M bug, and I'm thinking a 10M rig may have to be on my project list for this year.
73,
Will - KI4POV
KI4POV's Clock
KI4POV's N0WVA Regen
His QRZ page mentions a goal of Working All States, so I recommend he join Parks On The Air so he can use their spotting system (sorted to list only CW stations) to hunt for the states he needs, and another benefit is that the Activators will log all his contacts on the POTA website.
ReplyDeleteHi, Walter,
DeleteThanks for the recommendation! I’’m familiar with POTA, and you’re right, they do make it much easier to get state confirmations. In my case though, my goal is not just confirmations, but 50 physical QSL cards to hang on the wall in my shack. I don’t even plan to confirm the cards through the ARRL; just knowing that I did it is enough for me. Unfortunately, that means I often have to work a state two or three times to get a card back! That’s all part of the fun though.
Thanks and 73,
Will - KI4POV
Great work looks amazing something to be very proud of! That clock is very creative!!!!
ReplyDeleteThe Dymo tape labels are the cherry on top. Great colour on that blue metal too. Fearless evocation of the non commercial approach.
ReplyDeleteNice rigs! I really love the clock. I've got a bunch of old Weston 1mA f.s. round-face meters I might use to make one myself. Let me guess: three PWM signals from an MCU filtered to create time-varying current for the meters?
ReplyDeleteThere's a hobby manual from RCA from 1970 that shows meters as displays. BCD counters feeding a simple D/A converter. 1/2/4/8. You don't need precision since the steps are well apart.
DeleteI gather there were some comjercial equipment that used meters. The concept appeared in hobby magazines, but barely went anywhere. It relied on cheap meters. I suspect that by the time frequency counters took off, 7 segment LED readouts were cheap enough.
Michael--some of those old hobby magazines had some very-cool stuff, including electronics-themed fiction. My Dad had a collection of 1950s Popular Electronic that had the stories of Carl and Jerry, two high schoolers and their electronics high jinks.
DeleteThey weren't old when I first read them.
DeleteTodd, you've basically got the idea, except it's even easier than that. It is an MCU outputting 3 PWM signals, but the PWM signals are run straight into the meters with no filtering. The mechanical movement of the meters is slow-reacting enough that the needles appear steady and have no discernable jitter. I'd be glad to share the code if you're interested. My email is on my QRZ.
ReplyDeleteWill-- that's one of the nice things about analog meter movements: they steady the random dither of reality instead of throwing flashing segments in one's face. Thanks for the PWM concept. I think I'll enjoy working out the code on my own. That way I can pretend I know what I'm doing.
ReplyDelete