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Saturday, June 13, 2020
Jerry's Sproutie: A Short Wave Receiver (and a Limerick) by Jerry KI4IO
Wednesday, December 1, 2021
KI4IO in India and Nepal, and Discrete Homebrew Gilbert Cells
While in India I was licensed at VU2LHO and worked a lot of US hams with a 135' flat-top and open-wire feed. I had the antenna strung between two bamboo towers atop the embassy housing 2nd-story roof-top. I also put up a 3/8 wave vertical on the roof for 10 meters. That little antenna had 110 radials stapled into the roof screen and worked very well! The rig was a HW-101. I was in Kathmandu, Nepal from early 1980 to late 1982. I could not obtain a license there, but became good friends with Father Moran, 9N1MM, and would often spend time up at his place putting his Drake station on CW. Pretty cool being real DX! Back in the states in late 1982.
Tuesday, May 21, 2019
FDIM Interview with KI4IO -- Homebrew Direct Conversion Transceiver
I'm really glad that our ace correspondent Bob Crane W8SX caught up with Jerry at FDIM. I liked his description of the joy of using a homebrew rig, and of the advantages of direct conversion. Inspiring stuff! Listen to the interview here:
http://soldersmoke.com/KI4IO FDIM 2019.m4a
Wednesday, July 8, 2015
The Wizard of Warrenton: Jerry KI4IO
Sunday, May 28, 2023
Jerry KI4IO (Wizard of Warrenton) Describes His ALL ANALOG Phasing Transceiver -- Bob Crane FDIM interview #3 (audio)
Wow, this one really resonated with me. Jerry had me won over when, early in the interview, he described his decision to dispense with the Si5351/Arduino combo: "I said the hell with this digital stuff!" I hear you Jerry. I feel your pain OM.
Jerry then goes on to describe a rig with bits of circuitry from some legendary sources: The Ugly Weekender transmitter. SSDRA and EMRFD. W7ZOI's 1968 Direct Conversion receiver.
Jerry discusses the "presence" of the direct conversion receiver. And he decries the pernicious effects of AGC. (Indeed, real hams MANUALLY control the gain.)
The Wizard of Warrenton then shares some important tribal wisdom: After building that new piece of gear, leave it on the bench for a couple of weeks. Beware of "radio infatuation" (what a great term -- we will have to include this in the lexicon). Jerry points out that while at first, the new rig will seem just perfect, with time time the need for improvements and modifications will become apparent.
Jerry also has connections to India and Nepal (where he helped Father Moran). See: https://www.qrz.com/db/KI4IO
Here is W8SX's interview with Jerry:
http://soldersmoke.com/KI4IO23.mp3
Thanks Jerry! Thanks Bob!
Sunday, December 25, 2022
Some Direct Conversion Receiver History
Here is the article by Wes Hayward and Dick Bingham that started it all:
https://worldradiohistory.com/Archive-DX/QST/60s/QST-1968-11.pdf
page 15
Here's a discussion by Wes of the original project:
https://www.n5dux.com/ham/files/pdf/Direct%20Conversion%20Receivers%20History%20-%20W7ZOI.pdf
Here is an article about DC receiver in phasing rigs by Gary Breed K9AY:
https://worldradiohistory.com/Archive-DX/QST/80s/QST-1988-01.pdf
page 16
Roy Lewallen W7EL's Optimized transceiver (with a direct conversion receiver):
https://worldradiohistory.com/Archive-DX/QST/80s/QST-1980-08.pdf
page 14
Jerry KI4IO on Building a DC Receiver
https://groups.io/g/qrptech/message/17
Michael Black wrote on March 5, 2014 at 3:54 PM
Isn't it a bit dated?
When "direct conversion" receivers came along in 1968 (the concept existed before, just not the name), it was to build simple receivers. They took over from regens (which of course for the purpose of CW and SSB, were "direct conversion"), and kind of bumped simple superheterodyne receivers out of the magazines.
And they were easy to build, so long as the meaning of the dots were standard, but good performance was elusive. Endless articles about better mixers or more front end selectivity, and still the same basic results The Heathkit HW-7 comes along, and endless mods to that, but still no perfection.
Slowly the move was back to simple superhets, especially with some of the early seventies ICs intended for radio, and then ladder filters came along (actually they came early at least by 1974 from the UK and/or France, but while they got mention in North America early-ish, it took some years before the KVG filters were pushed aside and ladder filters got the spotlight).
And then wham, in the mid-eighties someone caught on. The problem with direct conversion receivers wasn't the mixer (well not once it was a balanced mixer) or lack of front-end selectivity, it was the matter of properly terminating the mixer. The problems that had been there all along were gone. And direct conversion receivers started their climb to being complicated receivers.
I guess it was that receiver by Gary Breed in QST circa 1986 with diode balanced mixers and termination that changed things. A new concept, but not really, I remember an article in QST in 1974 where a DBM diode mixer for VHF was properly terminated, and yet the concept went no further until a decade later.
Actually, I think there is a tiny bit about mixer termination in "Solid State Design for the Radio Amateur" but it never went so far as to say "this is what we need".
Or perhaps that tiny transceiver by Roy Llewellyn in QST was the first, I cant' remember. It certainly used a diode mixer with termination for the receiver.
And that set the stage for Rick Campbell's various receivers, all counting on termination of the mixer.
The ideas can often be there, but not applied because technology doesn't allow it yet, or just not looking that far beyond this month's construction article.
Michael
Saturday, June 27, 2020
SolderSmoke Podcast #223 Field Day, Club Talks, Patreon, NanoVNA, Farhan Video, SPRAT, BIG MAILBAG
Saturday, May 23, 2020
SolderSmoke Podcast #222 Antennas, Phasing, VFOs, 2-Bs, 6 years of N6QW, MAILBAG
After 46 years, finally a dial skirt |
N6QW Phase Shift Success -- It aint over 'till the fat lady sings |