Our intrepid correspondent Bob Crane interviewed FDIM speaker Jack Purdum W8TEE. Jack made some very intriguing comments on his efforts to enhance the beloved BITX transceiver. CW! AGC! Speech processing! Woo hoo! We await more details on how to acquire the board that Jack describes.
Jack is a very accomplished guy who has made many contributions to the radio art, most recently on Arduino microcontroller projects: https://www.qrz.com/db/W8TEE
Listen to Bob's interview with Jack here:
http://soldersmoke.com/FDIM17W8TEE.mp3
Thanks Jack! Thanks Bob!
Here are is the manual, bill of materials, and schematic for Jack's board:
http://soldersmoke.com/W8TEEschematic.pdf
http://soldersmoke.com/W8TEEmanual.doc
http://soldersmoke.com/W8TEEbom.doc
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Saturday, May 27, 2017
Friday, May 26, 2017
Homebrew Peppermint BITX: KC1FSZ Goes Scratch-built and Sweeps a Filter
Congratulations to Bill on the award. Very well deserved!
I just watched the video that Bill made with Farhan and I really enjoyed it. As usual, lots of useful information there.
Farhan’s demo of the Sweeperino was particularly timely because this past weekend I was doing something very similar.
As I’ve mentioned to Bill before, I am working on a scratch-built BITX to accompany the Peppermint BITX-40 module rig that I’m running right now. I took Pete’s advice and started from the audio end. After building the audio amplifier, product detector, and first/last pair of IF amplifiers, I was able to connect the VFO where the BFO is supposed to go and enjoy a pretty reasonable direct conversion receiver. It works great!! My first working receiver.
So my next step was the crystal filter. I puzzled over all of the different articles, tried to follow the G3UUR method, sorted crystals, etc. and finally put the whole thing together. But all along I’ve had this doubt that I could have possibly followed all of the steps closely enough to achieve the precision needed for a 3.5 KC SSB filter - it just didn’t seem possible.
Last week I decided to try to “sweep” the filter. This was a multi-day undertaking in itself. I pieced together the microprocessor, an AD9850, a TIA amplifier, the RF power detector from the SSDRA book, and some software that generates the necessary frequency sweep and collects power readings. The picture of the test rig is included below. It’s not much to look at.
With low expectations (and wires that are too long), I ran a few seeps and then downloaded the data onto my computer for analysis. No fancy software here, I’m just using Excel. When I put the data into a line chart in Excel, what emerged from the jumble of seemingly random numbers was a thing of beauty: a 3.5 KC passband right below 12 MHz. It’s the next stage beyond the Joy of Oscillation: The Joy Of Selectivity!
It’s even showing about the right insertion loss. Note the setup is very primitive and noisy so the fact that I can’t measure anything below -8dB isn’t surprising, you can ignore that part.
But I’m starting to get the feeling that this might actually work. Onto the diode mixer …
73s,
Bruce KC1FSZ https://www.qrz.com/db/kc1fsz
Labels:
BITX20,
BITX40Module,
Farhan,
Filters,
test gear
Thursday, May 25, 2017
VU3XVR's BEAUTIFUL Morse Keys
Truly a thing of beauty. Farhan gave me one of these. They are crafted by VU3XVR. It is enough to turn a phone-guy like me back to CW. Thanks Farhan!
Here is VU3XVR's site:
http://vu3xvr.blogspot.com/p/morse-key.html
Wednesday, May 24, 2017
FDIM: Listen to Bob Crane Interview Hans Summers, G0UPL
Bob Crane, our intrepid correspondent at the 2017 Four Day in May event, caught up with Homebrew Hero Hans Summers G0UPL. Hans's amazing web sites have been the inspiration for many projects in my shacks. My favorite so far was his QRSS transmitter using an LED based multivibrator circuit to generate a shark fin pattern on grabber screens. That was fun. I am now really tempted to send one of Hans's WSPR transmitters into the stratosphere using party balloons.
Listen to the interview here:
http://soldersmoke.com/FDIM17G0UPL.mp3
Visit Hans's QRP-Labs here:
https://www.qrp-labs.com/
Thanks Bob! Thanks Hans!
Listen to the interview here:
http://soldersmoke.com/FDIM17G0UPL.mp3
Visit Hans's QRP-Labs here:
https://www.qrp-labs.com/
Thanks Bob! Thanks Hans!
Labels:
balloon,
hamfest,
QRSS,
Summers-Hans
Monday, May 22, 2017
Video: Farhan in the SolderSmoke Shack! BITX, JBOTS, McDonald Straw Sig Gen, uBITX, Sweperino and more!
Thanks again to Farhan for visiting us. It was great to see his reaction to my humble implementations of his great designs. I got him to sign my BITX17. This was really a fantastic day for me and for my family.
Labels:
BITX DIGI-TIA,
BITX20,
BITX40Module,
Farhan,
Hayward--Wes,
India,
Juliano -- Pete,
Summers-Hans,
test gear
Sunday, May 21, 2017
Farhan Visits SolderSmoke Headquarters
Wow, today was an important day in the history of SolderSmoke. Our friend -- and newly minted member of the QRP Hall of Fame -- Ashhar Farhan VU2ESE came to see us. We had a great time. I showed him all the many devices that I built based on his designs.
We shot a video of the shack visit. I will post it to YouTube in a few days.
Thanks for coming to see us Farhan. And congratulations on the richly deserved Hall of Fame Induction.
Labels:
Farhan
Wednesday, May 17, 2017
Homebrew History is Made: Farhan @ W7ZOI
Thanks to Wes W7ZOI for sending me the link to his page describing the visit of our friend Farhan. I think this visit was a historic gathering of homebrew heroes and their groundbreaking rigs. Read all about it here: http://w7zoi.net/Farhan-visit.html
Please help me convince Farhan to visit SolderSmoke HQ before returning to India! Send him (or me) e-mails, texts, tweets, or just post messages of support below this post.
Labels:
Campbell-Rick,
Farhan,
Hayward--Wes,
India,
Lewallan -- Roy,
QRP,
radio history,
WA7MLH
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