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"QRP Classics" The Book that Got Me Started in Homebrew
A question this morning from Scott KQ4AOP caused me to Google this old bookย ย On page 59 I found the article about my first transmitter.ย Someone has put a copy of the entire book on the interenet.ย Here it is:ย
Sherwood: "It's Time to Clean Up our Transmitters"
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As an analog, HDR, discrete component, radical homebrew fundamentalist, obviously I have been concerned about all the hype about SDR.ย SDR advocates often make it sound as if those of us who build with discrete analog components (crystal filters!) are hopless troglodytes, about to be thrown on the ash heap of radio history.ย Or something like that.ย They sort of imply that without the cleansing benefits of SDR, our signals will remain hoplessly dirty.ย
I find it interesting that Sherwood concluded that the cleanest transmitter he ever owned was a Collins 32S-3!ย He compared the two tone output of this old rig to that of a modern transceiver.ย This was in 2019.ย See above.ย HDR wins.ย
Don't get me wrong.ย I want to clean up the signals from my HDR rigs.ย But I am encouraged by Sherwood's remarks.ย I do not think I will have to go SDR in order to have a clean signal.ย ย I may justย do some two-tone tests on the rigs,ย make some adjustments, and maybe build a class A Thermatron .1 kW linear.ย
IMD in Transmitters -- Splatter? Or Signal Strength?
https://www.newsvhf.com/conf2024/PresPapers/WA1MBA-IMD_in_Transmitters.pdf
Here is a good (and very recent) article on IMD ("splatter") produced in transmitters. The focus is on VHF, but much of this is relevant to HF operators.ย I found the footnotes on the ARRL "Clean Signal Initiative" to be worrisome.ย They seem to just be assuming that all ham operators will be using commercial gear, and the "OEM" needs to be made to meet certain standards. This seems to leave the homebrewer out in the cold.ย I can see where someday soon, the "standards" will exceed the capability of analog homebrewers.ย That would be bad.ย ย
The role that signal strength plays in the perception of "splatter" is often misunderstood by the "waterfall police."ย We often we hear some irate waterfall policeman screaming that,ย "You are 40 over and far too wide."ย ย Here is a good quote from the article on this point:ย
"If you have a calibrated spectrum display (as many SDRโs are these days), you can directly measure the level difference in dB. If it is 30 dB or more, then it could be an acceptably โclean signalโ, even if it is bothersome. Most ham voice communication is conducted with less than 30 dB signal/noise, and in that case the unwanted IMD is buried in the noise."
And even in a low noise environment,ย if the signal is 40 db over S9. that would mean the signal PEP is at -33dbm.ย If the IMD products are 46 db down from theย signal peak, that means your IMD products are -79 dbm.ย That is S-8!ย ย That signal will look quite wide in the waterfall, but it would be within FCC specs, right? The problem here is not so much distortion, as signal strength.ย And let's remember that "legal limit" is usually a misnomer:ย FCC regs require hams to use the minimum power necessary, not 1.5 kW on every single QSO.ย
The Surprising Difficulty of Analog Circuit Chip Design -- AI to the Rescue?
https://www.youtube.com/watch?v=lNypq1XuZRo
Really interesting.ย Why the design of the analog portions of chips is so much harder than the design of the digital portions.ย ย
Great channel.ย
Sony and the Transistor
I found the comment about Sony's belief that NPN transistors are superior to PNP very interesting.ย
IMD and Splatter
- SolderSmoke Daily News
- Ham Radio in the 1970s (and earlier, with some cool Jazz). What favorite rigs do you see?
Ham Radio in the 1970s (and earlier, with some cool Jazz). What favorite rigs do you see?
- SolderSmoke Daily News
- Excellent New Video from Grayson KJ7UM on his Thermatron version of the Michigan Mighty Mite
Excellent New Video from Grayson KJ7UM on his Thermatron version of the Michigan Mighty Mite
Who can tell us more about Lovelock's homebrew shortwave radio?
- SolderSmoke Daily News
- CuriousMarc Visits Cape Canaveral -- Lots of Space History (and some ham gear)
CuriousMarc Visits Cape Canaveral -- Lots of Space History (and some ham gear)
How to Homebrew your own Transistors
Mr. Carlson Makes a Thermatron Power Supply for a BC-348
SolderSmoke Quiz Question: Who is the actor in this Bell Labs video?
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"Matter Waves" -- A 1961 Bell Labs Film
- SolderSmoke Daily News
- Arthur C. Clarke Talks about Satellites, SETI, Remote Work, and Wrist Radios (1976 Video)
Arthur C. Clarke Talks about Satellites, SETI, Remote Work, and Wrist Radios (1976 Video)
"The Far Sound" -- Bell System Video from 1961 -- Good Radio History (video)
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- SolderSmoke Daily News
- Harry Caul had THE KNACK -- Movie Review -- "The Conversation" --1974 by Francis Ford Coppola (Harry Caul based on W3VCG)
Harry Caul had THE KNACK -- Movie Review -- "The Conversation" --1974 by Francis Ford Coppola (Harry Caul based on W3VCG)
I give it FIVE Soldering Irons!ย
I found it on Amazon Prime.ย The workshop scenes remind me of ham workshops.ย The movie character Harry Caul was based on real-life Marty Kaiser.ย Was Marty a ham?ย
POSTSCRIPT (August 23, 2024):ย Yes, he is a ham!ย ย W3VCG!ย ย FB.ย Here is his web site:ย
http://www.martykaiser.com/fbi1~1.htm
https://en.wikipedia.org/wiki/The_Conversation
http://www.martykaiser.com/odyssey2.htm
Thanks to Roy WN3F for reminding me to watch this film.ย Roy found a clip that is reminiscent of hamfests:ย https://www.youtube.com/watch?v=joM5VDCIQg8