Book recommendation please
 

Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?

I have purchased numerous books and cannot yet find one that is capable
of giving me enough clear information to do something useful (Or more to
the point, I cannot seem to get onto the same wavelength as these guys).

My predominant interest is VHF (150MHz). Low power (1 Watt or less), no
valves, no requirement to use rf transformers for matching through the
entire circuit.

Someone mentioned an analog design book a while ago and that may have
been appropriate and I could not remember the title. I thought it was
"The art and science of analog circuit design" so I purchased that book
and was disappointed to find it was full more of anecdotes of a bunch of
well seasoned engineers along with some handy tips.

Thanks

David

Book recommendation please
 

Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?

"Experimental Methods in RF Design" by Hayward, Campbell, and Larkin,
available from the ARRL, would be a good place to start. It's the
successor to the classic "Solid-State Design for the Radio Amateur"
from back in 1977.

If you can find copies of Doug Demaw's "Design notebook" and "QRP
notebook", there's some good reading there as well. Not as advanced
as "Experimental Methods" but perhaps a bit more accessible.

Buying a bunch of back issues of QRPp might also be helpful. In a lot
of the articles which discuss QRP receiver and transmitters, the
authors go into detail about their own particular circuit preferences,
tweaks, construction and debugging techniques, etc.

For a slightly deeper background, I'd recommend "Troubleshooting
Analog Circuits" by Robert Pease. It's not specific to RF but is full
of useful tricks and ideas.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Book recommendation please
 

Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).

Regards

David

Dave Platt wrote:
Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?

"Experimental Methods in RF Design" by Hayward, Campbell, and Larkin,
available from the ARRL, would be a good place to start. It's the
successor to the classic "Solid-State Design for the Radio Amateur"
from back in 1977.

If you can find copies of Doug Demaw's "Design notebook" and "QRP
notebook", there's some good reading there as well. Not as advanced
as "Experimental Methods" but perhaps a bit more accessible.

Buying a bunch of back issues of QRPp might also be helpful. In a lot
of the articles which discuss QRP receiver and transmitters, the
authors go into detail about their own particular circuit preferences,
tweaks, construction and debugging techniques, etc.

For a slightly deeper background, I'd recommend "Troubleshooting
Analog Circuits" by Robert Pease. It's not specific to RF but is full
of useful tricks and ideas.

Book recommendation please
 

Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).

For the primary matching stuff, that's true.

You might want to look at the sections on crystal filters... if I
recall properly, there are some filter arrangements which use an LC
match at one or both ends.

You might want to dig into the ARRL books on UHF and microwave, and
perhaps a copy of the old ARRL VHF manual (out of print but available
used).

I think, though, that you're probably out on the bleeding edge of
amateur experimentation. Not a lot of people are homebrewing VHF gear
these days, so there may not be a single book which goes into the sort
of circuitry you're interested in with an eye towards from-scratch
design work.

I'm looking right now at the ARRL VHF Manual's description of a
2-meter portable design, circa 1972 - AM transmitter and
superregenerative receiver. It's all solid-state - no tubes.
However, as with most such designs I've seen, it has quite a few
transformers in it - typically part of single- or double-tuned
resonant circuits between the stages. The design seems to do both the
tuned filtering, and the impedance matching with the same components -
not an unreasonable approach. The oscillator strips in a
commercially-built 2-meter FM repeater's transmitter and receiver I
tore apart recently use a similar approach.

If you really want a transformerless design, I'm sure it can be done,
but the necessary L/T/pi matches may end up being more difficult to
design, and trickier to tune than a more conventional
transformer-based design.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Book recommendation please
 

Dave,

At present I have an issue with a Butler emitter follower oscillator at
150MHz.

I have Matthy's "Crystal Oscillator Circuits" and Randall Rhea's
"Oscillator design and computer simulation" books. Also EMIRFD,
"Introduction to RF design by Wes Hayward", "Complete Wireless design by
Sayre", "RF design by Boswick", ARRL handbook, VHF/UHF handbook and a
few more fundamental electronics and antenna books but try as I might I
just cannot seem to ever extract enough information from all these books
combined to get a useful result.

The Butler design I am looking at has a circuit for 100MHz. I assume
this would be close enough to use the same typology but adjust the
tuning components for 150MHz.

The book mentions tuning near by not at resonance. I have no idea how
far "near" is and should it be above or below resonance or does it not
matter.

He then states the holder capacitance of the crystal is 4.2pF and that
he tunes this capacitance out with a 410nH inductor. If I calculate
this, I get 600nH inductor to tune out 4.2pF at 100MHz. Why would he use
410nH instead of the larger value ? No mention in the text.

He mentions that tuning "near" resonance is achieved with L and Cap from
base to emitter. He shows a 8-15pF cap. If I assume the trimmer set
about half way at say 12pF and use his value of L of 120nH then the
circuit is actually tuned to 132MHz. (I am not sure if this 30% higher
frequency is what e really means by "near resonance". He also does not
take into account the Base emitter capacitance or the cap to ground of
the c-tap. Is the assumption that these do not matter ?

I made the circuit with changes in values to try to achieve 150MHz and
it worked but had extremely critical tuning (very small adjustment in
the tuning C stopped the oscillation). It also appeared to run slightly
lower than the stamped marking on the crystal so I assume the either the
crystal is cut 100ppm lower for parallel mode or I have not tuned out
enough Co or something ?
This is where I now need more detail to understand why the circuit
behaves like this and what to do to fix it.

I would also like to change the bias current as the 19mA current draw is
a lot for my application. 5mA would be good but without properly
understanding how to calculate Rout of the emitter follower, I am not
sure the resistance is getting too high toi drive the crystal.

I have tried common base butler designs and they seemed to be easier to
get going and understand but several text point out this design is prone
to have instabilities and small ranges of inductance in the tuned tank
that they will run over.

I need to find some text that would cover issues like this but not so
deep mathematically that I need a degree to use the math.

Thanks




Dave Platt wrote:
Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).

For the primary matching stuff, that's true.

You might want to look at the sections on crystal filters... if I
recall properly, there are some filter arrangements which use an LC
match at one or both ends.

You might want to dig into the ARRL books on UHF and microwave, and
perhaps a copy of the old ARRL VHF manual (out of print but available
used).

I think, though, that you're probably out on the bleeding edge of
amateur experimentation. Not a lot of people are homebrewing VHF gear
these days, so there may not be a single book which goes into the sort
of circuitry you're interested in with an eye towards from-scratch
design work.

I'm looking right now at the ARRL VHF Manual's description of a
2-meter portable design, circa 1972 - AM transmitter and
superregenerative receiver. It's all solid-state - no tubes.
However, as with most such designs I've seen, it has quite a few
transformers in it - typically part of single- or double-tuned
resonant circuits between the stages. The design seems to do both the
tuned filtering, and the impedance matching with the same components -
not an unreasonable approach. The oscillator strips in a
commercially-built 2-meter FM repeater's transmitter and receiver I
tore apart recently use a similar approach.

If you really want a transformerless design, I'm sure it can be done,
but the necessary L/T/pi matches may end up being more difficult to
design, and trickier to tune than a more conventional
transformer-based design.

Book recommendation please
 

It sounds like some of the HP or Motorola app notes might be helpful for
this. Maybe someone can suggest some specific ones.

Roy Lewallen, W7EL

David wrote:
Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?

I have purchased numerous books and cannot yet find one that is capable
of giving me enough clear information to do something useful (Or more to
the point, I cannot seem to get onto the same wavelength as these guys).

My predominant interest is VHF (150MHz). Low power (1 Watt or less), no
valves, no requirement to use rf transformers for matching through the
entire circuit.

Someone mentioned an analog design book a while ago and that may have
been appropriate and I could not remember the title. I thought it was
"The art and science of analog circuit design" so I purchased that book
and was disappointed to find it was full more of anecdotes of a bunch of
well seasoned engineers along with some handy tips.

Thanks

David

Book recommendation please
 

On Mon, 28 Aug 2006 05:59:39 GMT, David
wrote:


Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).

Up to around 200mhz thats not a big issue if properly scaled and the
right ferrite used.

I've used a lot of ideas from that book at 6 and 2m. The book list
presented is one I'd have suggested and added the venerable handbook
both current and a few older copies.

Allison



Regards

David

Dave Platt wrote:
Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?

"Experimental Methods in RF Design" by Hayward, Campbell, and Larkin,
available from the ARRL, would be a good place to start. It's the
successor to the classic "Solid-State Design for the Radio Amateur"
from back in 1977.

If you can find copies of Doug Demaw's "Design notebook" and "QRP
notebook", there's some good reading there as well. Not as advanced
as "Experimental Methods" but perhaps a bit more accessible.

Buying a bunch of back issues of QRPp might also be helpful. In a lot
of the articles which discuss QRP receiver and transmitters, the
authors go into detail about their own particular circuit preferences,
tweaks, construction and debugging techniques, etc.

For a slightly deeper background, I'd recommend "Troubleshooting
Analog Circuits" by Robert Pease. It's not specific to RF but is full
of useful tricks and ideas.

Book recommendation please
 

Thanks for the feedback.

I do not have a ready supply of ferrite cores and do not really want to
wind coils.
I have surface mountable air fixed coils that provide Q 100 that I
expect should be suitable for most applications and use of trimmer
capacitors.

The only high frequency crystal oscillator I could find in the EMRFD
(100MHz) is page 4.15 which is a common base butler. I understand these
suffer parasitic effects, the tank is only effective for a limited range
of inductance. The butler emitter follower is offered as a more superior
typology but this circuit is not found in this book.
The circuit values in his example are incorrect as the 25nH inductor in
the tank requires over 100pF to resonate at 100MHz. The circuit shown
has a net capacitance of around 40pF ?
There is very little design information given with respect to ratio of
the C-Tap or emitter bias.
I also have his book "Introduction to Radio Frequency design". This does
go into more depth but is centred mainly around colpitts oscillators
(not good for harmonic crystal oscillators).





wrote:
On Mon, 28 Aug 2006 05:59:39 GMT, David
wrote:

Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).

Up to around 200mhz thats not a big issue if properly scaled and the
right ferrite used.

I've used a lot of ideas from that book at 6 and 2m. The book list
presented is one I'd have suggested and added the venerable handbook
both current and a few older copies.

Allison


Regards

David

Dave Platt wrote:
Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?
"Experimental Methods in RF Design" by Hayward, Campbell, and Larkin,
available from the ARRL, would be a good place to start. It's the
successor to the classic "Solid-State Design for the Radio Amateur"
from back in 1977.

If you can find copies of Doug Demaw's "Design notebook" and "QRP
notebook", there's some good reading there as well. Not as advanced
as "Experimental Methods" but perhaps a bit more accessible.

Buying a bunch of back issues of QRPp might also be helpful. In a lot
of the articles which discuss QRP receiver and transmitters, the
authors go into detail about their own particular circuit preferences,
tweaks, construction and debugging techniques, etc.

For a slightly deeper background, I'd recommend "Troubleshooting
Analog Circuits" by Robert Pease. It's not specific to RF but is full
of useful tricks and ideas.

Book recommendation please
 

Hi David,

I've read through the rest of the posts, and in general I think you have a
decent selection of books. The couple I'd add:

"RF Oscillator Circuit Analysis and Design with Breadboard Experiments" by
John Plastonek -- Which is no longer in print, but I could probably scan it in
one of these days if you can't find a copy kicking around (I've made active
efforts to find this Plastonek guy to ask him about this, and he seems to have
dropped off the face of the planet). His oscillator circuits go up to
~100MHz, and he has some discussion as to why you might prefer one oscillator
topology over another.

"Build Your Own Low-Power Transmitters: Projects for the Electronics
Experimenter" by Graf & Sheets (you can preview it on-line at Amazon.com).
He has plans in there for transmitters at pretty much all frequency from
LF-SHF, and although I haven't build anything in it myself :-), I've heard
from other people that the transmitters really do work.

"Practical RF Design Manual" by DeMaw -- Probably overlaps a lot of the of
DeMaw books; now distributed by MFJ.

BTW, I wouldn't be so quick to give up on RF transformers and matching -- any
RF circuit with active components in it is going to require some amount of
matching, and while at times you can get away without formally considering it,
doing so often gives up power or robustness. (I know it's a little
disheartening to open up a commercial radio and see that they managed to
achileve something like a stereo FM receiver all in 7 transistors and no RF
transformers, but such designs are the evolutionary results of a lot of people
spending a lot of time trying to cost minimize a product that's produced in
the millions. And keep in mind that something like a cell phone today
requires over 100 man years to design...)

Finally, don't write off books such as "The Art and Science of Analog Circuit
Design" -- it's a great example of one of those books that has a lot of great
advice in it, but until you've hit your head on the wall a few thousand times
encountering the particular problems the authors have, its value isn't
apparent. The sort of "tweaking" advice you're looking for with RF circuits
is precisely what TAaSoACD is trying to provide... just more to folks building
op-amps & data converters than RF circuit.

---Joel Kolstad

Book recommendation please
 

On Mon, 28 Aug 2006 13:25:40 GMT, David
wrote:

Thanks for the feedback.

I do not have a ready supply of ferrite cores and do not really want to
wind coils.
I have surface mountable air fixed coils that provide Q 100 that I
expect should be suitable for most applications and use of trimmer
capacitors.

The only high frequency crystal oscillator I could find in the EMRFD
(100MHz) is page 4.15 which is a common base butler. I understand these
suffer parasitic effects, the tank is only effective for a limited range
of inductance. The butler emitter follower is offered as a more superior
typology but this circuit is not found in this book.
The circuit values in his example are incorrect as the 25nH inductor in
the tank requires over 100pF to resonate at 100MHz. The circuit shown
has a net capacitance of around 40pF ?

Built as described, it works. However the 25nH is an approximation
as distributed C and also lead lengths add significantly. Mine tuned
with 33ohms substituted for the crystal from 93 to 122mhz.

There is very little design information given with respect to ratio of
the C-Tap or emitter bias.

Read the test as the concepts are outlined rather than how to design
xyz circuit in cookbook fashon. If you need help, the easy way is
to calculate the reactances at the shown frequency and then using
those numbers scale for the desired frequency. The bias point would
be the same at any frequency for a given transistor and power.

I also have his book "Introduction to Radio Frequency design". This does
go into more depth but is centred mainly around colpitts oscillators
(not good for harmonic crystal oscillators).

In general oscillators in the 20mhz range are harmonic or overtone
designs and more subject to parasitic effects. I've bult the 100mhz
design and it worked fine for me within the limits of the crystal used
though after a x4 multiplication the thermal drift was unacceptable
and the crystal was the first order contributor. The oscillator
otherwise behaved well.

My solution for the whole mess was a lower frequency osc
and using low order harmonics. The lower frequency crystale proved
both less fussy to oscilate and more stable in fundemental mode.
Note: I was interested in sufficient stability to copy SSB at ~1296mhz
so even a few dozen Hz drift is noticeable..

Allison





wrote:
On Mon, 28 Aug 2006 05:59:39 GMT, David
wrote:

Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).

Up to around 200mhz thats not a big issue if properly scaled and the
right ferrite used.

I've used a lot of ideas from that book at 6 and 2m. The book list
presented is one I'd have suggested and added the venerable handbook
both current and a few older copies.

Allison


Regards

David

Dave Platt wrote:
Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?
"Experimental Methods in RF Design" by Hayward, Campbell, and Larkin,
available from the ARRL, would be a good place to start. It's the
successor to the classic "Solid-State Design for the Radio Amateur"
from back in 1977.

If you can find copies of Doug Demaw's "Design notebook" and "QRP
notebook", there's some good reading there as well. Not as advanced
as "Experimental Methods" but perhaps a bit more accessible.

Buying a bunch of back issues of QRPp might also be helpful. In a lot
of the articles which discuss QRP receiver and transmitters, the
authors go into detail about their own particular circuit preferences,
tweaks, construction and debugging techniques, etc.

For a slightly deeper background, I'd recommend "Troubleshooting
Analog Circuits" by Robert Pease. It's not specific to RF but is full
of useful tricks and ideas.

Book recommendation please
 

From what I understand so far the bias should should not necessarily be
the same and the capacitors will not scale as suggested.

The ESR of the crystal would be different for different overtone
crystals so therefore the bias should change to provide correct
drive and C to ground on the C-Tap would also need to change. According
to Matthy the Cap to ground should be 0.5 to 1 x ESR and emitter drive
impedance less than ESR. Or have I misinterpreted something here ?

I am also unsure of whether the tank should be tuned above or below
resonance. Rhea's book suggests the tank should be capacitive at Fo
indicating the tank itself would be tuned above the operating frequency.

I would like to learn more about the Butler emitter follower crystal
oscillator.

If I ask the specific questions about this typology and someone gives me
an answer, where did they obtain this information. Have they learned by
just playing with the circuit in a hit and miss fashion or have they
first obtained fundamental information from some text and using what
they have learnt then played with the circuit. If so, what would this
text be ?


If Ro = Rsource/(beta+1), is Rsource in the oscillator case of the
emitter follower Rp of the coil in parallel with the bias resistance
or does it also include (Rphi+RE) x Beta. Is Beta used here an
approximation calculate by Ft/F ?




wrote:
On Mon, 28 Aug 2006 13:25:40 GMT, David
wrote:

Thanks for the feedback.

I do not have a ready supply of ferrite cores and do not really want to
wind coils.
I have surface mountable air fixed coils that provide Q 100 that I
expect should be suitable for most applications and use of trimmer
capacitors.

The only high frequency crystal oscillator I could find in the EMRFD
(100MHz) is page 4.15 which is a common base butler. I understand these
suffer parasitic effects, the tank is only effective for a limited range
of inductance. The butler emitter follower is offered as a more superior
typology but this circuit is not found in this book.
The circuit values in his example are incorrect as the 25nH inductor in
the tank requires over 100pF to resonate at 100MHz. The circuit shown
has a net capacitance of around 40pF ?

Built as described, it works. However the 25nH is an approximation
as distributed C and also lead lengths add significantly. Mine tuned
with 33ohms substituted for the crystal from 93 to 122mhz.

There is very little design information given with respect to ratio of
the C-Tap or emitter bias.

Read the test as the concepts are outlined rather than how to design
xyz circuit in cookbook fashon. If you need help, the easy way is
to calculate the reactances at the shown frequency and then using
those numbers scale for the desired frequency. The bias point would
be the same at any frequency for a given transistor and power.

I also have his book "Introduction to Radio Frequency design". This does
go into more depth but is centred mainly around colpitts oscillators
(not good for harmonic crystal oscillators).

In general oscillators in the 20mhz range are harmonic or overtone
designs and more subject to parasitic effects. I've bult the 100mhz
design and it worked fine for me within the limits of the crystal used
though after a x4 multiplication the thermal drift was unacceptable
and the crystal was the first order contributor. The oscillator
otherwise behaved well.

My solution for the whole mess was a lower frequency osc
and using low order harmonics. The lower frequency crystale proved
both less fussy to oscilate and more stable in fundemental mode.
Note: I was interested in sufficient stability to copy SSB at ~1296mhz
so even a few dozen Hz drift is noticeable..

Allison




wrote:
On Mon, 28 Aug 2006 05:59:39 GMT, David
wrote:

Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).
Up to around 200mhz thats not a big issue if properly scaled and the
right ferrite used.

I've used a lot of ideas from that book at 6 and 2m. The book list
presented is one I'd have suggested and added the venerable handbook
both current and a few older copies.

Allison


Regards

David

Dave Platt wrote:
Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?
"Experimental Methods in RF Design" by Hayward, Campbell, and Larkin,
available from the ARRL, would be a good place to start. It's the
successor to the classic "Solid-State Design for the Radio Amateur"
from back in 1977.

If you can find copies of Doug Demaw's "Design notebook" and "QRP
notebook", there's some good reading there as well. Not as advanced
as "Experimental Methods" but perhaps a bit more accessible.

Buying a bunch of back issues of QRPp might also be helpful. In a lot
of the articles which discuss QRP receiver and transmitters, the
authors go into detail about their own particular circuit preferences,
tweaks, construction and debugging techniques, etc.

For a slightly deeper background, I'd recommend "Troubleshooting
Analog Circuits" by Robert Pease. It's not specific to RF but is full
of useful tricks and ideas.

Book recommendation please
 

On Mon, 28 Aug 2006 23:38:38 GMT, David
wrote:

From what I understand so far the bias should should not necessarily be
the same and the capacitors will not scale as suggested.

The ESR of the crystal would be different for different overtone
crystals so therefore the bias should change to provide correct
drive and C to ground on the C-Tap would also need to change. According
to Matthy the Cap to ground should be 0.5 to 1 x ESR and emitter drive
impedance less than ESR. Or have I misinterpreted something here ?

The DC bias would be unchanged. The feedback required may need
to be altered but thats a product of frequency and transistor(or fet)
gain at the target frequency and any change in overtone used.

In short if the circuit shown uses a 100mhz crystal in a 7th overtone
mode it will scale if a 89mhz 7th overtone crystal is used. Usually
for a narrow range of frequencies like that the ERS varies but not
greatly. This does not cover the difference between good quality
crystal and poor quality crystals, If you going to use poor quality
crystals there may be other issues to investigate as well.

I am also unsure of whether the tank should be tuned above or below
resonance. Rhea's book suggests the tank should be capacitive at Fo
indicating the tank itself would be tuned above the operating frequency.

Believe it or not, doesn't matter. You'll build it and then have to
tune it for proper oscillation. At around 100mhz the circuit
parasitics such as coil construction, PC board trace capacitance
and inductance, transistor characteristics, transistor, coil and
capactior lead length are all in the mix.

I would like to learn more about the Butler emitter follower crystal
oscillator.

If I ask the specific questions about this typology and someone gives me
an answer, where did they obtain this information. Have they learned by
just playing with the circuit in a hit and miss fashion or have they
first obtained fundamental information from some text and using what
they have learnt then played with the circuit. If so, what would this
text be ?

Generally I try to avoid high order oscilators(overtone) as stability
and the need for being tuned doesn't suit my needs.

I've never seen a in depth analysis in any one book. I apply
my EE training plus 30+ years of theory vs what really happens
and go from there. Sometimes being an engineer is really more like
science where you observe and build or search out theory to explain
the observed behavour, or you break out the diddle stick and adjust
it and move on to bigger problems.

If Ro = Rsource/(beta+1), is Rsource in the oscillator case of the
emitter follower Rp of the coil in parallel with the bias resistance
or does it also include (Rphi+RE) x Beta. Is Beta used here an
approximation calculate by Ft/F ?

Thats all first order rule of thumb. However, are you trying to build
one working oscillator or flog it to death? I say that as I've found
it to be both less than an exact science and that accurate to more
than 3 decimal places is excess for operation. For one oscillator
it is both easy and practical to dead bug it and see if it meets
your needs. If you going to build in quantity something using it
that is a whole different set of issues.

Allison





wrote:
On Mon, 28 Aug 2006 13:25:40 GMT, David
wrote:

Thanks for the feedback.

I do not have a ready supply of ferrite cores and do not really want to
wind coils.
I have surface mountable air fixed coils that provide Q 100 that I
expect should be suitable for most applications and use of trimmer
capacitors.

The only high frequency crystal oscillator I could find in the EMRFD
(100MHz) is page 4.15 which is a common base butler. I understand these
suffer parasitic effects, the tank is only effective for a limited range
of inductance. The butler emitter follower is offered as a more superior
typology but this circuit is not found in this book.
The circuit values in his example are incorrect as the 25nH inductor in
the tank requires over 100pF to resonate at 100MHz. The circuit shown
has a net capacitance of around 40pF ?

Built as described, it works. However the 25nH is an approximation
as distributed C and also lead lengths add significantly. Mine tuned
with 33ohms substituted for the crystal from 93 to 122mhz.

There is very little design information given with respect to ratio of
the C-Tap or emitter bias.

Read the test as the concepts are outlined rather than how to design
xyz circuit in cookbook fashon. If you need help, the easy way is
to calculate the reactances at the shown frequency and then using
those numbers scale for the desired frequency. The bias point would
be the same at any frequency for a given transistor and power.

I also have his book "Introduction to Radio Frequency design". This does
go into more depth but is centred mainly around colpitts oscillators
(not good for harmonic crystal oscillators).

In general oscillators in the 20mhz range are harmonic or overtone
designs and more subject to parasitic effects. I've bult the 100mhz
design and it worked fine for me within the limits of the crystal used
though after a x4 multiplication the thermal drift was unacceptable
and the crystal was the first order contributor. The oscillator
otherwise behaved well.

My solution for the whole mess was a lower frequency osc
and using low order harmonics. The lower frequency crystale proved
both less fussy to oscilate and more stable in fundemental mode.
Note: I was interested in sufficient stability to copy SSB at ~1296mhz
so even a few dozen Hz drift is noticeable..

Allison




wrote:
On Mon, 28 Aug 2006 05:59:39 GMT, David
wrote:

Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).
Up to around 200mhz thats not a big issue if properly scaled and the
right ferrite used.

I've used a lot of ideas from that book at 6 and 2m. The book list
presented is one I'd have suggested and added the venerable handbook
both current and a few older copies.

Allison


Regards

David

Dave Platt wrote:
Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?
"Experimental Methods in RF Design" by Hayward, Campbell, and Larkin,
available from the ARRL, would be a good place to start. It's the
successor to the classic "Solid-State Design for the Radio Amateur"
from back in 1977.

If you can find copies of Doug Demaw's "Design notebook" and "QRP
notebook", there's some good reading there as well. Not as advanced
as "Experimental Methods" but perhaps a bit more accessible.

Buying a bunch of back issues of QRPp might also be helpful. In a lot
of the articles which discuss QRP receiver and transmitters, the
authors go into detail about their own particular circuit preferences,
tweaks, construction and debugging techniques, etc.

For a slightly deeper background, I'd recommend "Troubleshooting
Analog Circuits" by Robert Pease. It's not specific to RF but is full
of useful tricks and ideas.

Book recommendation please
 

Thanks for the information.

The book example uses a 5th OT 100MHz crystal. My application uses a 7th
OT 151 MHz crystal.

I suspect the ESR jumps from around 60-70 in the 5th OT to a max. of
120R for the 7th OT.

Something I find a little confusing though in in Matthys book at the
beginning he explains that in series mode, the lower the impedances
driving and loading the crystal - the better as this ensures the crystal
has maximum control of the feedback path.

But during his explanation of the butler emitter follower, he mentions
the load cannot be "too" small and suggests optimal load of 1/2 to 1 x
ESR. Can you shed some light on this for me please.

I realise another option is to build a 3rd OT oscillator followed by
a tripler and filtering but I find when I do this that I have trouble
getting rid of harmonics. Also each tank circuit ends up adding lots of
cost to the circuit as I usually use a fixed air-wound SMD format coil
and SMD trimmer cap and these are expensive.

Another option was I could use a PLL as I have a heap of the LMX1602.
Then the trouble is that the microcontroller overhead goes.(Having to
set frequency each time the system boots). I also looked at other PLL
ICs like the motorola devices that can be pre-programmed with pin
settings but these seem to be hard to obtain now.

Thanks again. I appreciate the time people have taken to consider my
questions and provide me with some valuable insight that I have not yet
gained from experience. (I suppose that is the power of such a forum as
this anyway).

regards

David




wrote:
On Mon, 28 Aug 2006 23:38:38 GMT, David
wrote:

From what I understand so far the bias should should not necessarily be
the same and the capacitors will not scale as suggested.

The ESR of the crystal would be different for different overtone
crystals so therefore the bias should change to provide correct
drive and C to ground on the C-Tap would also need to change. According
to Matthy the Cap to ground should be 0.5 to 1 x ESR and emitter drive
impedance less than ESR. Or have I misinterpreted something here ?

The DC bias would be unchanged. The feedback required may need
to be altered but thats a product of frequency and transistor(or fet)
gain at the target frequency and any change in overtone used.

In short if the circuit shown uses a 100mhz crystal in a 7th overtone
mode it will scale if a 89mhz 7th overtone crystal is used. Usually
for a narrow range of frequencies like that the ERS varies but not
greatly. This does not cover the difference between good quality
crystal and poor quality crystals, If you going to use poor quality
crystals there may be other issues to investigate as well.

I am also unsure of whether the tank should be tuned above or below
resonance. Rhea's book suggests the tank should be capacitive at Fo
indicating the tank itself would be tuned above the operating frequency.

Believe it or not, doesn't matter. You'll build it and then have to
tune it for proper oscillation. At around 100mhz the circuit
parasitics such as coil construction, PC board trace capacitance
and inductance, transistor characteristics, transistor, coil and
capactior lead length are all in the mix.

I would like to learn more about the Butler emitter follower crystal
oscillator.

If I ask the specific questions about this typology and someone gives me
an answer, where did they obtain this information. Have they learned by
just playing with the circuit in a hit and miss fashion or have they
first obtained fundamental information from some text and using what
they have learnt then played with the circuit. If so, what would this
text be ?

Generally I try to avoid high order oscilators(overtone) as stability
and the need for being tuned doesn't suit my needs.

I've never seen a in depth analysis in any one book. I apply
my EE training plus 30+ years of theory vs what really happens
and go from there. Sometimes being an engineer is really more like
science where you observe and build or search out theory to explain
the observed behavour, or you break out the diddle stick and adjust
it and move on to bigger problems.

If Ro = Rsource/(beta+1), is Rsource in the oscillator case of the
emitter follower Rp of the coil in parallel with the bias resistance
or does it also include (Rphi+RE) x Beta. Is Beta used here an
approximation calculate by Ft/F ?

Thats all first order rule of thumb. However, are you trying to build
one working oscillator or flog it to death? I say that as I've found
it to be both less than an exact science and that accurate to more
than 3 decimal places is excess for operation. For one oscillator
it is both easy and practical to dead bug it and see if it meets
your needs. If you going to build in quantity something using it
that is a whole different set of issues.

Allison




wrote:
On Mon, 28 Aug 2006 13:25:40 GMT, David
wrote:

Thanks for the feedback.

I do not have a ready supply of ferrite cores and do not really want to
wind coils.
I have surface mountable air fixed coils that provide Q 100 that I
expect should be suitable for most applications and use of trimmer
capacitors.

The only high frequency crystal oscillator I could find in the EMRFD
(100MHz) is page 4.15 which is a common base butler. I understand these
suffer parasitic effects, the tank is only effective for a limited range
of inductance. The butler emitter follower is offered as a more superior
typology but this circuit is not found in this book.
The circuit values in his example are incorrect as the 25nH inductor in
the tank requires over 100pF to resonate at 100MHz. The circuit shown
has a net capacitance of around 40pF ?
Built as described, it works. However the 25nH is an approximation
as distributed C and also lead lengths add significantly. Mine tuned
with 33ohms substituted for the crystal from 93 to 122mhz.

There is very little design information given with respect to ratio of
the C-Tap or emitter bias.
Read the test as the concepts are outlined rather than how to design
xyz circuit in cookbook fashon. If you need help, the easy way is
to calculate the reactances at the shown frequency and then using
those numbers scale for the desired frequency. The bias point would
be the same at any frequency for a given transistor and power.

I also have his book "Introduction to Radio Frequency design". This does
go into more depth but is centred mainly around colpitts oscillators
(not good for harmonic crystal oscillators).
In general oscillators in the 20mhz range are harmonic or overtone
designs and more subject to parasitic effects. I've bult the 100mhz
design and it worked fine for me within the limits of the crystal used
though after a x4 multiplication the thermal drift was unacceptable
and the crystal was the first order contributor. The oscillator
otherwise behaved well.

My solution for the whole mess was a lower frequency osc
and using low order harmonics. The lower frequency crystale proved
both less fussy to oscilate and more stable in fundemental mode.
Note: I was interested in sufficient stability to copy SSB at ~1296mhz
so even a few dozen Hz drift is noticeable..

Allison



wrote:
On Mon, 28 Aug 2006 05:59:39 GMT, David
wrote:

Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).
Up to around 200mhz thats not a big issue if properly scaled and the
right ferrite used.

I've used a lot of ideas from that book at 6 and 2m. The book list
presented is one I'd have suggested and added the venerable handbook
both current and a few older copies.

Allison


Regards

David

Dave Platt wrote:
Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?
"Experimental Methods in RF Design" by Hayward, Campbell, and Larkin,
available from the ARRL, would be a good place to start. It's the
successor to the classic "Solid-State Design for the Radio Amateur"
from back in 1977.

If you can find copies of Doug Demaw's "Design notebook" and "QRP
notebook", there's some good reading there as well. Not as advanced
as "Experimental Methods" but perhaps a bit more accessible.

Buying a bunch of back issues of QRPp might also be helpful. In a lot
of the articles which discuss QRP receiver and transmitters, the
authors go into detail about their own particular circuit preferences,
tweaks, construction and debugging techniques, etc.

For a slightly deeper background, I'd recommend "Troubleshooting
Analog Circuits" by Robert Pease. It's not specific to RF but is full
of useful tricks and ideas.

Book recommendation please
 

On Tue, 29 Aug 2006 20:41:09 GMT, David
wrote:

Thanks for the information.

The book example uses a 5th OT 100MHz crystal. My application uses a 7th
OT 151 MHz crystal.

I suspect the ESR jumps from around 60-70 in the 5th OT to a max. of
120R for the 7th OT.

I dont consider that a huge jump, considering the amount of tolereance
there is in that kind of thing.

Something I find a little confusing though in in Matthys book at the
beginning he explains that in series mode, the lower the impedances
driving and loading the crystal - the better as this ensures the crystal
has maximum control of the feedback path.

if the crystal feedbak path loads the crystal too greatly the problems
of mode jumping and poor starting are present.

But during his explanation of the butler emitter follower, he mentions
the load cannot be "too" small and suggests optimal load of 1/2 to 1 x
ESR. Can you shed some light on this for me please.

too low the osc will not start (low effective gain) and too high
allows for possible mode shifts.

I realise another option is to build a 3rd OT oscillator followed by
a tripler and filtering but I find when I do this that I have trouble
getting rid of harmonics. Also each tank circuit ends up adding lots of
cost to the circuit as I usually use a fixed air-wound SMD format coil
and SMD trimmer cap and these are expensive.

I would think using double tuned and properly coupled the undesired
harmonics should easily be more than 70db down. Requires some care in
layout and grounding.

Another option was I could use a PLL as I have a heap of the LMX1602.
Then the trouble is that the microcontroller overhead goes.(Having to
set frequency each time the system boots). I also looked at other PLL
ICs like the motorola devices that can be pre-programmed with pin
settings but these seem to be hard to obtain now.

Those headaches and also sidebands that are not well surpressed
if care is not taken make it potentially worse than 3rd OT and
tripler.

build and test is my suggestion.

Allison



wrote:
On Mon, 28 Aug 2006 23:38:38 GMT, David
wrote:

From what I understand so far the bias should should not necessarily be
the same and the capacitors will not scale as suggested.

The ESR of the crystal would be different for different overtone
crystals so therefore the bias should change to provide correct
drive and C to ground on the C-Tap would also need to change. According
to Matthy the Cap to ground should be 0.5 to 1 x ESR and emitter drive
impedance less than ESR. Or have I misinterpreted something here ?

The DC bias would be unchanged. The feedback required may need
to be altered but thats a product of frequency and transistor(or fet)
gain at the target frequency and any change in overtone used.

In short if the circuit shown uses a 100mhz crystal in a 7th overtone
mode it will scale if a 89mhz 7th overtone crystal is used. Usually
for a narrow range of frequencies like that the ERS varies but not
greatly. This does not cover the difference between good quality
crystal and poor quality crystals, If you going to use poor quality
crystals there may be other issues to investigate as well.

I am also unsure of whether the tank should be tuned above or below
resonance. Rhea's book suggests the tank should be capacitive at Fo
indicating the tank itself would be tuned above the operating frequency.

Believe it or not, doesn't matter. You'll build it and then have to
tune it for proper oscillation. At around 100mhz the circuit
parasitics such as coil construction, PC board trace capacitance
and inductance, transistor characteristics, transistor, coil and
capactior lead length are all in the mix.

I would like to learn more about the Butler emitter follower crystal
oscillator.

If I ask the specific questions about this typology and someone gives me
an answer, where did they obtain this information. Have they learned by
just playing with the circuit in a hit and miss fashion or have they
first obtained fundamental information from some text and using what
they have learnt then played with the circuit. If so, what would this
text be ?

Generally I try to avoid high order oscilators(overtone) as stability
and the need for being tuned doesn't suit my needs.

I've never seen a in depth analysis in any one book. I apply
my EE training plus 30+ years of theory vs what really happens
and go from there. Sometimes being an engineer is really more like
science where you observe and build or search out theory to explain
the observed behavour, or you break out the diddle stick and adjust
it and move on to bigger problems.

If Ro = Rsource/(beta+1), is Rsource in the oscillator case of the
emitter follower Rp of the coil in parallel with the bias resistance
or does it also include (Rphi+RE) x Beta. Is Beta used here an
approximation calculate by Ft/F ?

Thats all first order rule of thumb. However, are you trying to build
one working oscillator or flog it to death? I say that as I've found
it to be both less than an exact science and that accurate to more
than 3 decimal places is excess for operation. For one oscillator
it is both easy and practical to dead bug it and see if it meets
your needs. If you going to build in quantity something using it
that is a whole different set of issues.

Allison




wrote:
On Mon, 28 Aug 2006 13:25:40 GMT, David
wrote:

Thanks for the feedback.

I do not have a ready supply of ferrite cores and do not really want to
wind coils.
I have surface mountable air fixed coils that provide Q 100 that I
expect should be suitable for most applications and use of trimmer
capacitors.

The only high frequency crystal oscillator I could find in the EMRFD
(100MHz) is page 4.15 which is a common base butler. I understand these
suffer parasitic effects, the tank is only effective for a limited range
of inductance. The butler emitter follower is offered as a more superior
typology but this circuit is not found in this book.
The circuit values in his example are incorrect as the 25nH inductor in
the tank requires over 100pF to resonate at 100MHz. The circuit shown
has a net capacitance of around 40pF ?
Built as described, it works. However the 25nH is an approximation
as distributed C and also lead lengths add significantly. Mine tuned
with 33ohms substituted for the crystal from 93 to 122mhz.

There is very little design information given with respect to ratio of
the C-Tap or emitter bias.
Read the test as the concepts are outlined rather than how to design
xyz circuit in cookbook fashon. If you need help, the easy way is
to calculate the reactances at the shown frequency and then using
those numbers scale for the desired frequency. The bias point would
be the same at any frequency for a given transistor and power.

I also have his book "Introduction to Radio Frequency design". This does
go into more depth but is centred mainly around colpitts oscillators
(not good for harmonic crystal oscillators).
In general oscillators in the 20mhz range are harmonic or overtone
designs and more subject to parasitic effects. I've bult the 100mhz
design and it worked fine for me within the limits of the crystal used
though after a x4 multiplication the thermal drift was unacceptable
and the crystal was the first order contributor. The oscillator
otherwise behaved well.

My solution for the whole mess was a lower frequency osc
and using low order harmonics. The lower frequency crystale proved
both less fussy to oscilate and more stable in fundemental mode.
Note: I was interested in sufficient stability to copy SSB at ~1296mhz
so even a few dozen Hz drift is noticeable..

Allison



wrote:
On Mon, 28 Aug 2006 05:59:39 GMT, David
wrote:

Dave,

I do have EMIRFD but find almost all the circuits are based around rf
transformers for matching and most of them are low frequency (3MHz etc).
Up to around 200mhz thats not a big issue if properly scaled and the
right ferrite used.

I've used a lot of ideas from that book at 6 and 2m. The book list
presented is one I'd have suggested and added the venerable handbook
both current and a few older copies.

Allison


Regards

David

Dave Platt wrote:
Anyone recommend a "decent" book that would cover oscillators, small
signal RF amps and matching techniques sufficiently to enable a novice
to start experimenting with circuits and have enough detail in the text
to tweak the circuits to get them running properly ?
"Experimental Methods in RF Design" by Hayward, Campbell, and Larkin,
available from the ARRL, would be a good place to start. It's the
successor to the classic "Solid-State Design for the Radio Amateur"
from back in 1977.

If you can find copies of Doug Demaw's "Design notebook" and "QRP
notebook", there's some good reading there as well. Not as advanced
as "Experimental Methods" but perhaps a bit more accessible.

Buying a bunch of back issues of QRPp might also be helpful. In a lot
of the articles which discuss QRP receiver and transmitters, the
authors go into detail about their own particular circuit preferences,
tweaks, construction and debugging techniques, etc.

For a slightly deeper background, I'd recommend "Troubleshooting
Analog Circuits" by Robert Pease. It's not specific to RF but is full
of useful tricks and ideas.