Hmmm...

No, I don't believe I will have to read anything...

But, if you can't tell the difference between a white noise generator and an
osc giving a clean fundamental signal with greatly suppressed/filtered
harmonics (or even, non-existent harmonics), you may wish to read-up before
taking that project to the air...

John

"Ham op" wrote in message
...
White noise is a critical requirement of the Colpitts/Hartley oscillator
design.

Nothing new here!

You say you don't know why White noise is required. Better go read Terman or
other credible designers.

John Smith wrote:

Dave:

I have seen designs used which use a "white noise generator" at their osc.

Simply filter the freq you want from it and off you go...

John

"Dave Platt" wrote in message
...

In article nH6Ge.22103$HV1.10801@fed1read07,
Caveat Lector wrote:


Just out of curousity -- what modern Ham gear uses a Colpitts oscillator or
a swinging choke ??

I believe that a goodly percentage of fixed-frequency quartz crystal
oscillators use a Colpitts configuration in their feedback circuitry.
Pierce topologies are likely used, as well.

The L in such oscillators is the motional inductance of the crystal,
rather than the inductance of a wire-wound inductor, but the principle
is still the same.


Then why ask these questions on a 2005 Ham test ??

Because the circuits are still relevant, to either modern ham gear, or
to the older gear that many hams refurbish and use, or to both.


Maybe ask about a VCO or a crowbar circuit ??

VCOs require some form of positive feedback in order to oscillate.
This can be in a Colpitts configuration just as well as in any other.

Questions about a crowbar would certainly be relevant as well.

--
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!

.... not at all...

.... some are cmos/mosfet nand/nor gates, xtal controlled feedback--used as
osc's and only tuned by "pulling" the xtal with a cap, and the signal passed to
multipliers (multishot monostable vibrators) or freq dividers (dec/hex/oct) and
used with other signals (mixed) to produce still other/unique freqs.

Special purpose ic's are around which contain all this (except the xtal) on a
single chip.

There is probably much newer technology than this at this point, as all my
knowledge of this hardware is a decade or more old...

The cheapest/easiest equip uses a coil and cap (old vfo's) and/or xtal (vxo's.)

John

"Ham op" wrote in message
...
Caveat Lector wrote:

Just out of curousity -- what modern Ham gear uses a Colpitts oscillator or
a swinging choke ??

Then why ask these questions on a 2005 Ham test ??

Maybe ask about a VCO or a crowbar circuit ??


All of them!!! The reference oscillator in every phase locked loop is
generally a Colpitt's oscillator. I suspect that every oscillator in the VCO
circuit is also Colpitt's.

By simply asking the question you make the point!!!

The required level of knowledge for a license today is significantly poorer
than 40 or 50 years ago.

The same day I took the test for General, I also took and passed all
requirements for a first class Phone with RADAR endorsement. The engineer
administering the test told me if I wanted to take a really tough test, the
amateur extra was the most difficult given by the FCC.

Unfortunately at that time one had to wait a year to take advanced and two
years to take the Extra. I would sure like to see them reinstate the time
requirements so some of these young bucks could get a little seasoning
before advancing. Today you can get it all in one day. Then armed with your
brand new Extra; proceed to E-Ham and ask questions in the Elmer conference
that could be answered by an old time novice.

"Ham op" wrote in message
...

The required level of knowledge for a license today is significantly
poorer than 40 or 50 years ago.

Fred:

Yes. But those were simple times when much of what we take for granted today
loomed before us as dark mysteries...

Things are much more complex these days, BS, MS, PHD's are much more common per
capita and the general knowledge of the common person on the street is
magnitudes greater than the times you are speaking of.

No longer are people with a bit of knowledge in such demand.

Our colleges turn out highly educated individuals in vast numbers which stagger
the imagination. Indeed, seats in colleges are filled far too quickly, leaving
no room for those not fortunate to gain entrance.

It is quite possible the person you see before you in a lowly public service
position has a degree.

Across the board, +25% of all college grads are working at or near minimum wage
in a field outside their course of study--five years after they graduate; I
suspect this figure, which the colleges themselves claim, is rather low...

John

"Fred W4JLE" wrote in message
...
The same day I took the test for General, I also took and passed all
requirements for a first class Phone with RADAR endorsement. The engineer
administering the test told me if I wanted to take a really tough test, the
amateur extra was the most difficult given by the FCC.

Unfortunately at that time one had to wait a year to take advanced and two
years to take the Extra. I would sure like to see them reinstate the time
requirements so some of these young bucks could get a little seasoning
before advancing. Today you can get it all in one day. Then armed with your
brand new Extra; proceed to E-Ham and ask questions in the Elmer conference
that could be answered by an old time novice.

"Ham op" wrote in message
...

The required level of knowledge for a license today is significantly
poorer than 40 or 50 years ago.

John, I'm very serious when I say that 'white noise' is critical to
Colpitts/Hartley oscillator operation.

The feedback equation for oscillation requires a voltagecurrent gain
greater than 1 and a phase shift of 180 degrees [in simplified terms].

Starting conditions, in the absence of white noise, has zero input
voltage and hence zero output voltage and therefore no oscillation! The
presence of white noise provides the starting conditions, the Vin to be
amplified, and the tuned circuit, L and C, provides the frequency
discrimination, and the fundamental frequency of the oscillator. The
Capacitive voltage divider [Colpitts] or the Inductive voltage divider
[Hartley] provides the feedback factor. The active device, tube,
transistor, FET, etc. provides the gain and contributes to the phase shift.

White noise, frequency selectivity, gain greater than 1, and 180 degrees
phase shift are absolute requirements for an oscillator. In the absence
of any one there is NO oscillator. The white noise provides the starting
conditions for oscillation!!!

John Smith wrote:
Hmmm...

No, I don't believe I will have to read anything...

But, if you can't tell the difference between a white noise generator and an
osc giving a clean fundamental signal with greatly suppressed/filtered
harmonics (or even, non-existent harmonics), you may wish to read-up before
taking that project to the air...

John

Does that mean you don't maintain your equipment or know what to look
for when you open the cover?

Amateur Radio is supposed to encourage self learning in some [SOME]
phase of the electronic disciplines associated with the generation,
transmission, and reception of electromagnetic signals.

I consider that self learning requires more than finding and using the
ON/OFF button.

John Smith wrote:

... in the "olden days" it was expected you would be building that equipment
you were being tested on ...

... of course logic and reason now demands the removal of those questions ...

John

"Ham op" wrote in message
...

Caveat Lector wrote:


Just out of curousity -- what modern Ham gear uses a Colpitts oscillator or
a swinging choke ??

Then why ask these questions on a 2005 Ham test ??

Maybe ask about a VCO or a crowbar circuit ??

You miss the point! Totally missed the point!!

In the 'olden days', the exams were not multiple guess questions; and, they
were answered in front of an FCC Engineer. In the olden days one had to
commit to some real effort to get a license. In human nature we VALUE that
which we work for or invest for.

The crime in ham radio today is the 5 hour Saturday morning cram session
followed by a VE session; followed by a license; followed by loss of interest
in a year or so.

I live in a small town with 14 licensed 'hams' with only one active [me] and
only one HF station [mine].

IMO there is a significant difference between number of licenses issued or
valid and how many hams are on the air.

Point well made!! AMEN !!

Fred W4JLE wrote:

The same day I took the test for General, I also took and passed all
requirements for a first class Phone with RADAR endorsement. The engineer
administering the test told me if I wanted to take a really tough test, the
amateur extra was the most difficult given by the FCC.

Unfortunately at that time one had to wait a year to take advanced and two
years to take the Extra. I would sure like to see them reinstate the time
requirements so some of these young bucks could get a little seasoning
before advancing. Today you can get it all in one day. Then armed with your
brand new Extra; proceed to E-Ham and ask questions in the Elmer conference
that could be answered by an old time novice.

"Ham op" wrote in message
...


The required level of knowledge for a license today is significantly
poorer than 40 or 50 years ago.

Ham op:

Absolutely! Any amp is an oscillator, any oscillator is an amp... just depends
on how ya use it (mainly feedback.)

There is also the subjects of "thermal noise" and "quantum noise", both
contribute to the ease which with a circuit begins and sustains oscillations...

Well, unless the laws of physics have changed!

John

"Ham op" wrote in message
news
John, I'm very serious when I say that 'white noise' is critical to
Colpitts/Hartley oscillator operation.

The feedback equation for oscillation requires a voltagecurrent gain greater
than 1 and a phase shift of 180 degrees [in simplified terms].

Starting conditions, in the absence of white noise, has zero input voltage
and hence zero output voltage and therefore no oscillation! The presence of
white noise provides the starting conditions, the Vin to be amplified, and
the tuned circuit, L and C, provides the frequency discrimination, and the
fundamental frequency of the oscillator. The Capacitive voltage divider
[Colpitts] or the Inductive voltage divider [Hartley] provides the feedback
factor. The active device, tube, transistor, FET, etc. provides the gain and
contributes to the phase shift.

White noise, frequency selectivity, gain greater than 1, and 180 degrees
phase shift are absolute requirements for an oscillator. In the absence of
any one there is NO oscillator. The white noise provides the starting
conditions for oscillation!!!

John Smith wrote:
Hmmm...

No, I don't believe I will have to read anything...

But, if you can't tell the difference between a white noise generator and an
osc giving a clean fundamental signal with greatly suppressed/filtered
harmonics (or even, non-existent harmonics), you may wish to read-up before
taking that project to the air...

John

Ham op:

Just where do you get a soldering iron which is small enough to deal with smc
components, these boards are done by machine. The world has gone surface mount
technology yanno...

I only work on the mikes, low pass/high pass/bandpass filters, linears and
feedlines, antennas, parts which are still big enough to handle...

My receiver is a PCI card for my computer (100khz-180Mhz, there are a couple of
birdies on the 2.8Ghz it is mounted in, these were not apparent when it was in
a 900Mhz motherboard) and the xmitter is a continuous full coverage 3-5 watt
transmitter PCI card 100khz-250mhz... computer sound card doubles as the
output audio for the receiver and dsp mike input for the transmitter...
driver/linear is external... different faces(skins) for the receiver (on the
monitor) are software selectable, any mode is possible, with the proper
software--even those NOT invented yet...

My "equip" is pretty much my computer these days, but I do have some ancient
gonset, johnson, hallicrafters, drake which I have not used in over a year.

Got some heavy duty chicken band equip too, but the computer is highly capable
of 11 meters, but not type accepted for CB...

John

John

"Ham op" wrote in message
...
Does that mean you don't maintain your equipment or know what to look for
when you open the cover?

Amateur Radio is supposed to encourage self learning in some [SOME] phase of
the electronic disciplines associated with the generation, transmission, and
reception of electromagnetic signals.

I consider that self learning requires more than finding and using the ON/OFF
button.

John Smith wrote:

... in the "olden days" it was expected you would be building that equipment
you were being tested on ...

... of course logic and reason now demands the removal of those questions
...

John

"Ham op" wrote in message
...

Caveat Lector wrote:


Just out of curousity -- what modern Ham gear uses a Colpitts oscillator or
a swinging choke ??

Then why ask these questions on a 2005 Ham test ??

Maybe ask about a VCO or a crowbar circuit ??

You miss the point! Totally missed the point!!

In the 'olden days', the exams were not multiple guess questions; and, they
were answered in front of an FCC Engineer. In the olden days one had to
commit to some real effort to get a license. In human nature we VALUE that
which we work for or invest for.

The crime in ham radio today is the 5 hour Saturday morning cram session
followed by a VE session; followed by a license; followed by loss of
interest in a year or so.

I live in a small town with 14 licensed 'hams' with only one active [me] and
only one HF station [mine].

IMO there is a significant difference between number of licenses issued or
valid and how many hams are on the air.

Nonsense John, today's college graduate is more in line with the high school
graduates of the fifties. I hired enough of your "highly educated"
graduates to be more than a casual observer.

They knew every thing there was to know about political correctness, liberal
thinking, and how to bitch if they were not given everything on a platter
the day they hired in.

I assigned an engineer the task of designing a simple serial interface to a
piece of equipment. He told me "we didn't cover that in school". Today A's
are passed out to everyone, in some schools, so as not to make the others
feel bad.

Give me an old time ham or a Navy trained technician, at least they had the
basics. Many of today's graduates are over paid at minimum wage.

"John Smith" wrote in message
...
Fred:

Yes. But those were simple times when much of what we take for granted
today
loomed before us as dark mysteries...

Things are much more complex these days, BS, MS, PHD's are much more
common per
capita and the general knowledge of the common person on the street is
magnitudes greater than the times you are speaking of.

No longer are people with a bit of knowledge in such demand.

Our colleges turn out highly educated individuals in vast numbers which
stagger
the imagination. Indeed, seats in colleges are filled far too quickly,
leaving
no room for those not fortunate to gain entrance.

It is quite possible the person you see before you in a lowly public
service
position has a degree.

Across the board, +25% of all college grads are working at or near minimum
wage
in a field outside their course of study--five years after they graduate;
I
suspect this figure, which the colleges themselves claim, is rather low...

John

"Fred W4JLE" wrote in message
...
The same day I took the test for General, I also took and passed all
requirements for a first class Phone with RADAR endorsement. The
engineer
administering the test told me if I wanted to take a really tough test,
the
amateur extra was the most difficult given by the FCC.

Unfortunately at that time one had to wait a year to take advanced and
two
years to take the Extra. I would sure like to see them reinstate the
time
requirements so some of these young bucks could get a little seasoning
before advancing. Today you can get it all in one day. Then armed with
your
brand new Extra; proceed to E-Ham and ask questions in the Elmer
conference
that could be answered by an old time novice.

"Ham op" wrote in message
...

The required level of knowledge for a license today is significantly
poorer than 40 or 50 years ago.