Re: 7 MHz Oscillator Ideas
The si5351 is a great part, and only costs $1.
You do need a processor to communicate with the si5351 via its i2c bus,
but a low end msp430 these days is $0.50.
With that, a 25mhz reference crystal, and a couple button switches for up/down, you have a vfo.
Maybe have the si5351 stop for 100ms each time it passes through a multiple of 25khz
so you can audibly keep track of where the vfo is.
Would work fine, assuming you filter out any incoming high frequency RF from the antenna?
that might mix with harmonics of the si5351's square wave.
But part of the attraction of a DC receiver is that it is a very simple analog circuit
that's easy to understand.?
No digital magic.
Jerry
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On Tue, Dec 10, 2019 at 12:05 PM, Jim Pruitt wrote:
Would it be of any value to use a Si5351 module like the Adafruit module ($7 from them or Mouser or Digikey) or a homebrew one like VK3PE makes that is a drop in replacement for the Adafruit
Yes,? the Si5351's are 10 pin smt devices but they are about $2.25 each in small quantities and seem to be used a lot these days or you could buy the Adafruit module that is already soldered for you.? A cheap mechanical encoder could also be used with them.? Yes that does complicate the design by requiring that a PIC chip or Arduino chip or module also be included in the design but I would guess the parts for something like that in a simple DC receiver would be around $25.? Adding a display would drive the cost up and complicate it but is a display really even needed?? I would suspect that there is a way to set the frequency range of the module without using a cpu but I do not know what it is.
Thank you.
Jim Pruitt
WA7DUY
|
Re: 7 MHz Oscillator Ideas
It is stable enough because of the use of the crystals.
However, if this was an LC circuit, you definitely want voltage into that pot to be regulated.
The voltage applied to the diode is always some ratio of your unregulated supply,
the ratio being determined by the pot.
This matters even when you set the pot to give the diode 3v.
Jerry
?
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On Tue, Dec 10, 2019 at 12:52 PM, Chuck Carpenter wrote:
The capacitance beyond 10V changes very little.? The plotted curves by k7qo?in the attached chart show that. The MV209 is similar to the BB910 that I used.
Note too that the curve for the 1N4004 shows very little change beyond about 4-5 V. That curve is typical of junctions from devices like diodes and LEDs and etc. The max C might be more or less at 0V depending on the size of the junction.? But the shape of the curves is about the same.
|
Re: 7 MHz Oscillator Ideas
Jerry,
The capacitance beyond 10V changes very little.? The plotted curves by k7qo?in the attached chart show that. The MV209 is similar to the BB910 that I used.
Note too that the curve for the 1N4004 shows very little change beyond about 4-5 V. That curve is typical of junctions from devices like diodes and LEDs and etc. The max C might be more or less at 0V depending on the size of the junction.? But the shape of the curves is about the same.
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
|
Re: 7 MHz Oscillator Ideas
Would it be of any value to use a Si5351 module
like the Adafruit module ($7 from them or Mouser or Digikey) or a
homebrew one like VK3PE makes that is a drop in replacement for
the Adafruit
Yes,? the Si5351's are 10 pin smt devices but they are about $2.25
each in small quantities and seem to be used a lot these days or
you could buy the Adafruit module that is already soldered for
you.? A cheap mechanical encoder could also be used with them.?
Yes that does complicate the design by requiring that a PIC chip
or Arduino chip or module also be included in the design but I
would guess the parts for something like that in a simple DC
receiver would be around $25.? Adding a display would drive the
cost up and complicate it but is a display really even needed?? I
would suspect that there is a way to set the frequency range of
the module without using a cpu but I do not know what it is.
Thank you.
Jim Pruitt
WA7DUY
On 12/10/2019 2:58 AM, Chuck Carpenter
wrote:
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Jerry,
I get about 3 kHz with a pair of crystals on 7MHz using the
"fixture" in the picture.? I measured that with a 10V tuning
range.
The SA612?oscillator is running from the 6V regulator circuit so
the frequency isn't affected by supply voltage changes.
The GQRP Sudden RX kit uses a VFO for tuning.? You could take a
shot at that using those 9mm cans...8^)
They take a lot of space.? I built one of those?for someone and it
seemed to be fairly stable.? I found a source for?new cans but
they are rather pricy.
The RX for my project was intended for installation in mint tins
as shown in sketch pic.???
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
|
Re: What level math is in the RF design books?
William,
Try this:? Vrms = 0.3535 * Vpp? then, Po = Vrms*2 / 100
That's the simplest approximation.
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
|
Re: 7 MHz Oscillator Ideas
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Show quoted text
On Tue, Dec 10, 2019, 04:58 Chuck Carpenter < w5usj@...> wrote: Jerry,
I get about 3 kHz with a pair of crystals on 7MHz using the "fixture" in the picture.? I measured that with a 10V tuning range.
The SA612?oscillator is running from the 6V regulator circuit so the frequency isn't affected by supply voltage changes.
The GQRP Sudden RX kit uses a VFO for tuning.? You could take a shot at that using those 9mm cans...8^)
They take a lot of space.? I built one of those?for someone and it seemed to be fairly stable.? I found a source for?new cans but they are rather pricy.
The RX for my project was intended for installation in mint tins as shown in sketch pic.???
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
|
Re: 7 MHz Oscillator Ideas
Would not be an issue with the tuning range limited to 3khz..
However, the frequency determining pot for the varactor diode is operating directly from the power supply.
?
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Show quoted text
On Tue, Dec 10, 2019 at 02:58 AM, Chuck Carpenter wrote:
The SA612?oscillator is running from the 6V regulator circuit so the frequency isn't affected by supply voltage changes.
|
Re: 7 MHz Oscillator Ideas
this is the vfo I made from Solid State Design
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Re: 7 MHz Oscillator Ideas
I built a simple regenerative receiver awhile ago using VK3YE design Rob mentioned and linked ?? Stable, sensitive.? Two transistors, a resonator, and an LM386, some parallel diodes as tuning capacitance rather than air variable.? No toroids.? First build was manhattan, second etched a "muppet" board.? Mine tunes 7025-75, am impressed with it's simplicity.? The ceramic resonators are about 25 cents from Mouser.
I was trying different regen receiver circuits with less than stellar results.? This one works very well.
|
Re: 7 MHz Oscillator Ideas
Tried to add two attachments at a time --- Didn't work...8^(
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
|
Re: 7 MHz Oscillator Ideas
Jerry,
I get about 3 kHz with a pair of crystals on 7MHz using the "fixture" in the picture.? I measured that with a 10V tuning range.
The SA612?oscillator is running from the 6V regulator circuit so the frequency isn't affected by supply voltage changes.
The GQRP Sudden RX kit uses a VFO for tuning.? You could take a shot at that using those 9mm cans...8^)
They take a lot of space.? I built one of those?for someone and it seemed to be fairly stable.? I found a source for?new cans but they are rather pricy.
The RX for my project was intended for installation in mint tins as shown in sketch pic.???
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
|
Re: What level math is in the RF design books?
Rob,
I would say a couple terms into a calculus sequence for that equation to lose its mystery.?
So by the end of a freshman year for an engineering student.
There is some physics there too, a math major might solve it without knowing what it means.
But you don't need to solve that equation to be good at designing a radio.
Read EMRFD.
Jerry
?
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On Mon, Dec 9, 2019 at 04:20 PM, Rob wrote:
what math class teaches how to solve this equation.
?
|
Re: What level math is in the RF design books?
I am a 60 year old retired computer programmer......... with
failing vision.
I have written software for everything from tiny microcontrollers
to track satellites with DOS computers to IBM mainframes the size
of a football field.
I have written accounting software and manufacturing software and
911 systems and software for pacemakers in your chest.
and
all ..without ever spending a day in a college classroom.
and
not once....
not ever...?? did a boss ever say to me "solve for X".
In all of that lifetime of computer programming there never was
an algebra exam.
So... now... in my old age and tinkering with radio circuits I
dabble with these books
and
yes...?? Experimental Methods in RF Design is one of them here.
and
I know I don't know anything more than basic algebra.... so when
something like the EBERS-MOLL equation
is presented to me I asked the question ...what math class
teaches how to solve this equation.
?
On 12/09/2019 02:02 PM, Ryan Flowers
wrote:
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Show quoted text
This reminds me of the question I asked in the old
group regarding an oscilloscope. I wondered if it was possible
to homebrew?a sideband transmitter without one, and the answer
was "definitely!" It turns out that even the experienced folks
tune with not much else than another transceiver. Oh, ok! Sounds
good to me lol.?
I think the overall attitude in the homebrew world
gravitates to "learn by doing" no "learn by learning" and I'm
cool with that.?
On the other hand, if I've misunderstood misrepresented
something in that statement, please accept my apologies and
feel free to tell me to shaddup :p?
?
You
will find that there are online calculators or models you
can use for most everything you?might want to do.? The
tougher issue is to understand the how and why of
electronics.? On your own, that will take many years to
learn.? Most of the folks in this group are experts in
their own areas, but will willingly tell you they are
still learning.? So, don't worry about the math or the
hairy technological details, just jump in and enjoy.? Dale
On Mon, Dec 9, 2019 at
8:55 AM Jerry Gaffke via Groups.Io <jgaffke= [email protected]>
wrote:
It all depends on how
deep you want to go.
For example, most radio amateurs would evaluate an antenna
system by measuring the SWR.
But you won't really understand it unless you embrace the
notion of a complex impedance,
and make use of those dim memories of sqrt(-1) from your
high school algebra class.?
Experimental Methods in RF Design (EMRFD) is probably the
book you want.
Anything that fails to go that deep, you will have a hard
time cooking up
new designs that actually work well.? Mostly patching
together pieces of stuff
that other people have published.
You will need a whole lot of time, as it's a thick read
with lots of new concepts.
Some of those pages will take a day of fiddling with
before it really sinks in.
And maybe access to a forum somewhere to ask the
inevitable questions.
It's got plenty of math in there, relative to the typical
QST article.
But nothing I didn't see in a high school algebra class.
I almost never did use calculus in my 40 yr career as an
EE.
Some engineers wind up in a job where they use it every
day.
Figuring out calculus does give you a tool for better
understanding the world,
especially the world of electronics.?
For example, how a capacitor charges up over time.
So useful even if you don't actually *use* it.
Introduction to Radio Frequency design (by the same
author) is a good taste
of what you will run into if you decide to get a degree in
Electrical Engineering.
What you do coming out of school with an EE degree is wide
open.
Could be working on a better generator for Bonneville Dam.
Could be digital design with boards full of FPGA's and
mostly writing VHDL.
Analog design (perhaps a radio), mostly reading ap notes
from chip manufacturers
on their hot new parts, trying out your design in a
simulator on a computer.
Could be getting the recipe just right for a silicon fab
line.
That last one would require intimate knowledge of the
Ebers-Moll model.
For the second to the last, reading EMRFD thoroughly would
get you most of the way there.
Jerry, KE7ER
On Mon, Dec 9, 2019 at 05:40 AM, Michael Maiorana wrote:
Rob,
Start
with college-level algebra. My professor called
algebra "the language of mathematics".?
Then,
Calculus (1, 2 and 3) along with engineering level
Physics (physics with calculus).?
Then
Differential equations.
Then
semiconductor physics and electronic materials.
Then
you'll be there.
?
Or...
you could use the empirical?methods which are covered
thoroughly?in Wes's EMRFD book.
?
Mike M
KU4QO
--
--
Ryan Flowers W7RLF
|
Re: What level math is in the RF design books?
Rob,
Ouch! That's going to leave a mark!
It's a fair cop, as the Brit villains say. I went through college begging for a grade in calculus, retired two years ago and *finally* started to do some of the math I haven't used in 45 years -- even got an HP calculator and learned RPN.
Still have trouble calculating power from Vp-p, however.??
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
|
Re: What level math is in the RF design books?
And while I'm at it, I'll recommend two other books:
The Art of Electronics, Horowitz and Hill. A classic
RF Circuit Design, Chris Boswick. Lots of practical design info and exercises
Eric KE6US
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On 12/9/2019 4:17 AM, Rob via Groups.Io wrote: What level of math course would I need to study to learn how to comprehend the equations presented in
design books like Introduction to Radio Frequency Design?? by W7ZOI.
|
Re: What level math is in the RF design books?
About 15 years ago, I had a website appropriately called
KE6US.com. I actually reviewed both EMRFD and Intro to RF Design.?
Wes was kind enough to send me a thank you email for the reviews.
Experimental Methods in RF Design, by
Wes Hayward (W7ZOI), Rick Campbell (KK7B), Bob Larkin (W7PUA).?
Hands down, the best book on homebrew design for hams ever
published. I refer to it constantly. My copy is dog-eared and
annotated on almost every page. I have modeled a number of the
circuits in SPICE.? I have also built quite a few of them.
Includes a jam-packed CD of valuable articles and other stuff.
Published by?.
Introduction to Radio Frequency Design,
by Wes Hayward (W7ZOI). You best pour through "Introduction to
Advanced Mathematics" and "Introduction to Electronic Design"
before tackling this one. I doubt the average ham would find
this book useful. It was originally published by Prentice-Hall
as a text for the "working engineer". Wes says he wished it
was available for his "career change from electron device
physics to rf circuit design." If you're contemplating a
similar career change, I recommend this book, otherwise, you
might want to hold off. There are lots of books better suited
to even advanced hams. Published by?.
I understand that level of math. In
grad school (economics), I took most math classes with engineering
students. However, understanding the math doesn't necessarily
equip you for understanding the concepts. I am a native English
speaker, but that doesn't mean I can understand everything a
theoretical physicist or classical philosopher has to say...in
English.
So I stand by what I said at the time.
For even above average hams, stick with EMRFD. You will need high
school math at most and a very curious mind. If you can get
through everything in that book, you won't need much else for
empirical design. I wouldn't discourage seriously skimming RFD
though.
Eric KE6US
On 12/9/2019 4:17 AM, Rob via Groups.Io
wrote:
toggle quoted message
Show quoted text
What level of
math course would I need to study to learn how to comprehend the
equations presented in
design books like Introduction to Radio Frequency Design?? by?
W7ZOI.
|
Re: What level math is in the RF design books?
It's one thing to build a known good design.
Quite another to design something that is fundamentally novel,
making the necessary calculations and measurements to get it performing well.
Yes, you can tinker with stuff and iterate to something that works better.
Sometimes.
But you will have much better luck if you understand what's going on.
When designing a radio there are many itradeoffs to be made.
You will need more than another transceiver to fully evaluate some new design.
Jerry, KEy7ER
?
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Show quoted text
On Mon, Dec 9, 2019 at 11:02 AM, Ryan Flowers wrote:
This reminds me of the question I asked in the old group regarding an oscilloscope. I wondered if it was possible to homebrew?a sideband transmitter without one, and the answer was "definitely!" It turns out that even the experienced folks tune with not much else than another transceiver. Oh, ok! Sounds good to me lol.?
?
I think the overall attitude in the homebrew world gravitates to "learn by doing" no "learn by learning" and I'm cool with that.?
?
On the other hand, if I've misunderstood misrepresented something in that statement, please accept my apologies and feel free to tell me to shaddup :p?
?
|
Re: What level math is in the RF design books?
This reminds me of the question I asked in the old group regarding an oscilloscope. I wondered if it was possible to homebrew?a sideband transmitter without one, and the answer was "definitely!" It turns out that even the experienced folks tune with not much else than another transceiver. Oh, ok! Sounds good to me lol.?
I think the overall attitude in the homebrew world gravitates to "learn by doing" no "learn by learning" and I'm cool with that.?
On the other hand, if I've misunderstood misrepresented something in that statement, please accept my apologies and feel free to tell me to shaddup :p? ?
You will find that there are online calculators or models you can use for most everything you?might want to do.? The tougher issue is to understand the how and why of electronics.? On your own, that will take many years to learn.? Most of the folks in this group are experts in their own areas, but will willingly tell you they are still learning.? So, don't worry about the math or the hairy technological details, just jump in and enjoy.? Dale
On Mon, Dec 9, 2019 at 8:55 AM Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote: It all depends on how deep you want to go.
For example, most radio amateurs would evaluate an antenna system by measuring the SWR.
But you won't really understand it unless you embrace the notion of a complex impedance,
and make use of those dim memories of sqrt(-1) from your high school algebra class.?
Experimental Methods in RF Design (EMRFD) is probably the book you want.
Anything that fails to go that deep, you will have a hard time cooking up
new designs that actually work well.? Mostly patching together pieces of stuff
that other people have published.
You will need a whole lot of time, as it's a thick read with lots of new concepts.
Some of those pages will take a day of fiddling with before it really sinks in.
And maybe access to a forum somewhere to ask the inevitable questions.
It's got plenty of math in there, relative to the typical QST article.
But nothing I didn't see in a high school algebra class.
I almost never did use calculus in my 40 yr career as an EE.
Some engineers wind up in a job where they use it every day.
Figuring out calculus does give you a tool for better understanding the world,
especially the world of electronics.?
For example, how a capacitor charges up over time.
So useful even if you don't actually *use* it.
Introduction to Radio Frequency design (by the same author) is a good taste
of what you will run into if you decide to get a degree in Electrical Engineering.
What you do coming out of school with an EE degree is wide open.
Could be working on a better generator for Bonneville Dam.
Could be digital design with boards full of FPGA's and mostly writing VHDL.
Analog design (perhaps a radio), mostly reading ap notes from chip manufacturers
on their hot new parts, trying out your design in a simulator on a computer.
Could be getting the recipe just right for a silicon fab line.
That last one would require intimate knowledge of the Ebers-Moll model.
For the second to the last, reading EMRFD thoroughly would get you most of the way there.
Jerry, KE7ER
On Mon, Dec 9, 2019 at 05:40 AM, Michael Maiorana wrote:
Rob,
Start with college-level algebra. My professor called algebra "the language of mathematics".?
Then, Calculus (1, 2 and 3) along with engineering level Physics (physics with calculus).?
Then Differential equations.
Then semiconductor physics and electronic materials.
Then you'll be there.
?
Or... you could use the empirical?methods which are covered thoroughly?in Wes's EMRFD book.
?
Mike M
KU4QO
--
-- Ryan Flowers W7RLF
https://miscdotgeek.com
|
Re: What level math is in the RF design books?
You will find that there are online calculators or models you can use for most everything you?might want to do.? The tougher issue is to understand the how and why of electronics.? On your own, that will take many years to learn.? Most of the folks in this group are experts in their own areas, but will willingly tell you they are still learning.? So, don't worry about the math or the hairy technological details, just jump in and enjoy.? Dale
On Mon, Dec 9, 2019 at 8:55 AM Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote: It all depends on how deep you want to go.
For example, most radio amateurs would evaluate an antenna system by measuring the SWR.
But you won't really understand it unless you embrace the notion of a complex impedance,
and make use of those dim memories of sqrt(-1) from your high school algebra class.?
Experimental Methods in RF Design (EMRFD) is probably the book you want.
Anything that fails to go that deep, you will have a hard time cooking up
new designs that actually work well.? Mostly patching together pieces of stuff
that other people have published.
You will need a whole lot of time, as it's a thick read with lots of new concepts.
Some of those pages will take a day of fiddling with before it really sinks in.
And maybe access to a forum somewhere to ask the inevitable questions.
It's got plenty of math in there, relative to the typical QST article.
But nothing I didn't see in a high school algebra class.
I almost never did use calculus in my 40 yr career as an EE.
Some engineers wind up in a job where they use it every day.
Figuring out calculus does give you a tool for better understanding the world,
especially the world of electronics.?
For example, how a capacitor charges up over time.
So useful even if you don't actually *use* it.
Introduction to Radio Frequency design (by the same author) is a good taste
of what you will run into if you decide to get a degree in Electrical Engineering.
What you do coming out of school with an EE degree is wide open.
Could be working on a better generator for Bonneville Dam.
Could be digital design with boards full of FPGA's and mostly writing VHDL.
Analog design (perhaps a radio), mostly reading ap notes from chip manufacturers
on their hot new parts, trying out your design in a simulator on a computer.
Could be getting the recipe just right for a silicon fab line.
That last one would require intimate knowledge of the Ebers-Moll model.
For the second to the last, reading EMRFD thoroughly would get you most of the way there.
Jerry, KE7ER
On Mon, Dec 9, 2019 at 05:40 AM, Michael Maiorana wrote:
Rob,
Start with college-level algebra. My professor called algebra "the language of mathematics".?
Then, Calculus (1, 2 and 3) along with engineering level Physics (physics with calculus).?
Then Differential equations.
Then semiconductor physics and electronic materials.
Then you'll be there.
?
Or... you could use the empirical?methods which are covered thoroughly?in Wes's EMRFD book.
?
Mike M
KU4QO
|
Re: 7 MHz Oscillator Ideas
Chuck, that looks pretty good.
How much tuning range do you get?
Is it best to have the crystals of slightly different frequency, and by how much?
How sensitive is the tuning to changes in battery voltage?
The crystals would give stability, but would lock you into tuning just a few khz.
Maybe an option to switch from the crystals to an LC tank circuit,
so the user can explore something other than a few CW signals.
Jerry, KE7ER
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On Mon, Dec 9, 2019 at 04:08 AM, Chuck Carpenter wrote:
Kinda late with this.? Attached a schematic and picture?of a simple RX that I've built?like you mentioned.? They are based on versions of the original MRX-40 in 1997 QST, the original Sudden RX from GQRP, Sudden Rx from QRPme and others.?Info available.? The assembled version is from an artwork I did using ExpressPCB.
The front end can be the tunable version shown or a band pass.? I've worked up a couple of BPFs that tested nicely using simple thru-hole parts.
Using crystals as VXOs gives you tuning range and crystal stability.?
|
Chuck Carpenter
k6whp
Dale Hardin KS4NS