Re: Xtaflex; A Crystal-Controlled Regenerative Detector
This was a similar rediscovery to me in 1997. see: An Ultra Simple W1AW Receiver by Charles Kitchin, N1TEV and Mike Murphy, WB2UID for QST May 1997
Our circuit could better be described as a direct conversion regenerative receiver using a colorburst crystal to receive W1AW. The Germanium diode is in effect, a product detector in this circuit.
Mike M. WU2D (former WB2UID)
- Sure John,
With some simple switching I do not see whay not but low power is the right class all right.
Actually back in the 1970's I used to run a single crystal (7145, 7147 kHz) controlled 2N2222 on 40M in my college room. I figure that I was getting 50 mW to the long wire! Even so I worked stations down to the Carolinas from upstate NY. That was before a lot of the shortwave was on that portion. Perhaps now the band is supposedly clean again from broadcasters we can use rigs like this again!
P.S. running CW in college does not attact girls.
--- In email@example.com, "John Berry." <jbbr35487@...> wrote:
> Hmm,good idea,looks like it could be used as the basis for a low power TX as well ??.John G1WOS.
- Mike, I really dig your unique circuits. If it were a few years ago, back
in the ancient days of paper, I'd suggest you publish a booklet under
the Babani press or maybe Popular Science - something like a latter-day
"Radio for the Millions".
I had thought about such a circuit too, just thought about it, and
I probably would have used the crystal at the base junction, but yours
It occurred to me that as long as for CW and SSB modes the circuit
is in the oscillating mode, would this work with a 1/2 or even 1/3
frequency crystal operating at its harmonic? The idea being to have
an ultrasimple but stable receiver for 20 meters or 15 meters, or
for one of the 10M SSB calling frequencies.
BTW, Michael, here's food for thought. I saw in EPE or Elektor a
circuit for a bat-monitor receiver, yes, for listening to bats. The
circuit basically used a ultrasonic microphone with a 1-transistor
audio stage feeding right into one of those chips the hams use
mostly for DC receivers, a balanced modulator chip, something like
the NE602. This was crystal controlled in this circuit, so there were
only 2 active "devices" - one transistor and one chip. The idea was
that the audio was transmitted as a low power DSB signal to a
nearby HF receiver. It occurred to me that if using a carbon
microphone the audio stage could possibly be eliminated and one
transistor then used as a PA for the DSB chip, thus having an
ultra simple QRP DSB transmitter.
I find looking at these ultra simple and effective circuits such as
the Crystalflex, as relaxing as a cup of good tea.
-Hue Miller K7HUE
[Non-text portions of this message have been removed]
- Thank you, everyone, for your replies. My thanks as well to Hue for his good thoughts and ideas.
Mike, W2UD; thank you for the "heads-up" on the "Ultra Simple W1AW Receiver" by MM. Murphy and Kitchin! I wonder if someone would be kind enough to send me a copy of your May, 1997, "QST Magazine" article? It sounds like I might have re-invented the wheel again (at least a little one). :o)
Gosh, it reminds me of when I used to be consumed by dreaming up proofs for ancient, Japanese Temple Geometry problems. A number of times I found that my "original" proof was nearly identical to one discovered by some anonymous, 17th century Japanese farmer or rice merchant. Despite our vast differences of age, custom and language, I thought it was wonderful that we ended up traveling by the same road. I went on to wonder how close our thoughts must be when we see a mountain half-covered in the morning mist, for example.
I tightened up the response of the Xtaflex bandpass filter last night until only a trace of 40m SWBCI was heard. Heard some DX using my 7015kHz crystal; quite a few Russian and eastern EU stations. Pretty neat with one ancient, Philco transistor!
Speaking of which, I read yesterday that Philco Semiconductor had built a state-of-the-art, plant at the end of the 1950's for the purpose of making their MADT and PADT surface-barrier transistors. The plant cost them $40 million dollars (over $200 million in today's currency). This, less than a year before Fairchild introduced the planar process; and thus rendering the Philco devices obsolete in one fell swoop. They never recovered.
--- In firstname.lastname@example.org, Hue Miller <kargo_cult@...> wrote:
> Mike, I really dig your unique circuits. If it were a few years ago, back
> in the ancient days of paper, I'd suggest you publish a booklet under
> the Babani press or maybe Popular Science - something like a latter-day
> "Radio for the Millions".
> I had thought about such a circuit too, just thought about it, and
> I probably would have used the crystal at the base junction, but yours works.
> I find looking at these ultra simple and effective circuits such as
> the Crystalflex, as relaxing as a cup of good tea.
> -Hue Miller K7HUE
- Sadly Hue,
It would have to be "Radio for the Thousands". Not too many eager young folks left out there to build these circuits...
- --- In email@example.com, "Mike" <mjmurphy45@...> wrote:
>young folks left out there to build these circuits...
> Sadly Hue,
> It would have to be "Radio for the Thousands". Not too many eager
I sometimes think there are more Yahoo groups devoted to ham radio and
related subjects than the total number of people reading them!