Jim Thompson wrote:
On Tue, 24 Feb 2004 15:29:43 GMT, "Rick Karlquist N6RK"
wrote:


You're probably thinking of the oscillator that Marv Frerking
called a "grounded-base oscillator". I have seen it called other
names as well. Basically, what you do is first build an LC
(ie no xtal) Colpitts oscillator and tune it to the crystal frequency
you want to eventually use.

[snip]

Sounds like an oscillator that I've used since the '60's for my G-jobs
(you know, the ones that *have* to work, 'cause they're for me .

See "XtalSeriesOsc.pdf" on the S.E.D/Schematics page of my website.

I've never been able to get any custom IC customers to use it, since
it takes three pins, but it works, period, no messy matching issues,
even handles overtone modes.

...Jim Thompson

This pdf schematic looks very similar, except for the crystal and emitter
part, to a circuit described in "Experimental Methods in RF Design" (p4.13).

The circuit is described as "worth building......to observe first hand just
what a noisy oscillator will sound like in a receiver".

Earlier in the same chapter it appears in figure 4.13 as a type of negative
resistance one port oscillator.

I can only assume that the changes and crystal (in the circuit shown in the
pdf) solve the problem of the "noisy" LC only configuration.

I mention it as I built it up last night and took it into work today in order
to have a look at the output on a spectrum analyser. Output was quite low at
-27dBm. Sadly the HP kit couldn't measure phase noise directly, and I didn't
have a good crystal oscillator to check it against.

We were uncertain regarding the configuration too, but my colleague worked out
that it had severe voltage limiting features and predicted the output swing
quite accurately before it was measured on a scope.

Last night I tried it with a number of inductors from the junk box and it
oscillated quite readily from 114MHz down to 5MHz. I quite like the use of a
non tapped L and only a single C. Shame about the phase noise :-(.

regards...

--Gary

On Tue, 24 Feb 2004 12:26:22 -0700, Jim Thompson
wrote:

On Tue, 24 Feb 2004 15:29:43 GMT, "Rick Karlquist N6RK"
wrote:

You're probably thinking of the oscillator that Marv Frerking
called a "grounded-base oscillator". I have seen it called other
names as well. Basically, what you do is first build an LC
(ie no xtal) Colpitts oscillator and tune it to the crystal frequency
you want to eventually use.
[snip]

Sounds like an oscillator that I've used since the '60's for my G-jobs
(you know, the ones that *have* to work, 'cause they're for me .

See "XtalSeriesOsc.pdf" on the S.E.D/Schematics page of my website.

I've never been able to get any custom IC customers to use it, since
it takes three pins, but it works, period, no messy matching issues,
even handles overtone modes.

...Jim Thompson

Aha! I just noted from Paul's post that "my" oscillator is called a
two-transistor Butler. Wonder when that was conceived? I've been
using the my direct-coupled version for 40 years.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

Jim Thompson wrote:
On Tue, 24 Feb 2004 15:29:43 GMT, "Rick Karlquist N6RK"
wrote:


You're probably thinking of the oscillator that Marv Frerking
called a "grounded-base oscillator". I have seen it called other
names as well. Basically, what you do is first build an LC
(ie no xtal) Colpitts oscillator and tune it to the crystal frequency
you want to eventually use.

[snip]

Sounds like an oscillator that I've used since the '60's for my G-jobs
(you know, the ones that *have* to work, 'cause they're for me .

See "XtalSeriesOsc.pdf" on the S.E.D/Schematics page of my website.

I've never been able to get any custom IC customers to use it, since
it takes three pins, but it works, period, no messy matching issues,
even handles overtone modes.

...Jim Thompson

This pdf schematic looks very similar, except for the crystal and emitter
part, to a circuit described in "Experimental Methods in RF Design" (p4.13).

The circuit is described as "worth building......to observe first hand just
what a noisy oscillator will sound like in a receiver".

Earlier in the same chapter it appears in figure 4.13 as a type of negative
resistance one port oscillator.

I can only assume that the changes and crystal (in the circuit shown in the
pdf) solve the problem of the "noisy" LC only configuration.

I mention it as I built it up last night and took it into work today in order
to have a look at the output on a spectrum analyser. Output was quite low at
-27dBm. Sadly the HP kit couldn't measure phase noise directly, and I didn't
have a good crystal oscillator to check it against.

We were uncertain regarding the configuration too, but my colleague worked out
that it had severe voltage limiting features and predicted the output swing
quite accurately before it was measured on a scope.

Last night I tried it with a number of inductors from the junk box and it
oscillated quite readily from 114MHz down to 5MHz. I quite like the use of a
non tapped L and only a single C. Shame about the phase noise :-(.

regards...

--Gary

You're probably thinking of the oscillator that Marv Frerking
called a "grounded-base oscillator".

Alternatively, take a look at the Butler design by John Stephensen in
November/December 1999 QEX. He explains clearly why folks ever had problems
with Butlers and better yet, how to cure them. I've used this circuit
(without the Varactor tuning) on 9th overtone oscillators using hound dog
crystals.

W4ZCB

On Tue, 24 Feb 2004 15:29:43 GMT, "Rick Karlquist N6RK"
wrote:

You're probably thinking of the oscillator that Marv Frerking
called a "grounded-base oscillator". I have seen it called other
names as well. Basically, what you do is first build an LC
(ie no xtal) Colpitts oscillator and tune it to the crystal frequency
you want to eventually use.
[snip]

Sounds like an oscillator that I've used since the '60's for my G-jobs
(you know, the ones that *have* to work, 'cause they're for me .

See "XtalSeriesOsc.pdf" on the S.E.D/Schematics page of my website.

I've never been able to get any custom IC customers to use it, since
it takes three pins, but it works, period, no messy matching issues,
even handles overtone modes.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

"Paul Burridge" wrote in message
news

Hi,

I'm trying to track down the name for a certain type of oscillator
which I dimly recall seeing in an old book called Radio & Line
Transmission that I bought and lost over 3 decades ago.
In simple terms, it has a crystal in the base/emitter circuit and a
C/L tank for the resonant frequency of the crystal in the collector
circuit. In this way it can't flip into an overtone since it only has
gain at the crystal's fundamental. Anyone know the name for it?

Why don't you think the crystal goes low impedance at it's odd harmonics? If
you'll design the circuit properly, it will give no trouble with overtone
operation. Don't remember ever having any problems selecting one to operate
on the fundamental, usually, it's selecting between 5th and 7th overtone or
7th and 9th that gets a little sticky.

W4ZCB

You're probably thinking of the oscillator that Marv Frerking
called a "grounded-base oscillator". I have seen it called other
names as well. Basically, what you do is first build an LC
(ie no xtal) Colpitts oscillator and tune it to the crystal frequency
you want to eventually use. Then insert a resistor of a few
dozen ohms in series with the emitter. Now, readjust the feedback
capacitors on the oscillator to get it to oscillate OK with the resistor.
Finally, replace the resistor with a series resonant crystal.
It will be forced to oscillate at the frequency of the original LC
oscillator, since there is no gain anywhere else. Thus you can
design for either the fundamental or a specific harmonic and like
you say it can't flip to a different overtone. For more details,
read one of Frerking's books.

Rick N6RK

"Paul Burridge" wrote in message
news

Hi,

I'm trying to track down the name for a certain type of oscillator
which I dimly recall seeing in an old book called Radio & Line
Transmission that I bought and lost over 3 decades ago.
In simple terms, it has a crystal in the base/emitter circuit and a
C/L tank for the resonant frequency of the crystal in the collector
circuit. In this way it can't flip into an overtone since it only has
gain at the crystal's fundamental. Anyone know the name for it?

Thanks,

p.

--

The BBC: Licensed at public expense to spread lies.