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

In article j5M_b.5335$AL.133044@attbi_s03, Harold E. Johnson
writes


What's a "hound dog crystal"?

How to deal with butlers:
http://etext.library.adelaide.edu.au...chapter41.html


Best regards,
Spehro Pefhany



Thanks Spehro. Delightful! I wondered what it had to do with things until
down the page a bit.

Sorry for the lack of definition, I was referring to crystals not
specifically treated to enhance overtone operation. When a manufacturer
makes a crystal for overtone use, he/she treats it to suppress spurious
responses close by the desired overtone so the crystal "likes" to
operate
properly. An untreated crystal often will have those responses and
oscillate
on one or more of them instead of the desired frequency unless the
feedback
and tuned circuit are carefully managed to ignore them. The higher
impedance of Stephensens schematic make that a bit easier to do.


The special techniques were as follows:
Optimise the plating thickness for the overtone and also the electrode
diameter.
Shear mode crystals have a controlled relationship between the resonant
frequency under the electrode and the frequency away from the
electroded region.

Also higher overtones are better polished and more sensitive to
parallelism.

Overtones pull less approx pulling of fundimental/overtone number
squared.



--
ddwyer

In article j5M_b.5335$AL.133044@attbi_s03, Harold E. Johnson
writes


What's a "hound dog crystal"?

How to deal with butlers:
http://etext.library.adelaide.edu.au...chapter41.html


Best regards,
Spehro Pefhany



Thanks Spehro. Delightful! I wondered what it had to do with things until
down the page a bit.

Sorry for the lack of definition, I was referring to crystals not
specifically treated to enhance overtone operation. When a manufacturer
makes a crystal for overtone use, he/she treats it to suppress spurious
responses close by the desired overtone so the crystal "likes" to
operate
properly. An untreated crystal often will have those responses and
oscillate
on one or more of them instead of the desired frequency unless the
feedback
and tuned circuit are carefully managed to ignore them. The higher
impedance of Stephensens schematic make that a bit easier to do.


The special techniques were as follows:
Optimise the plating thickness for the overtone and also the electrode
diameter.
Shear mode crystals have a controlled relationship between the resonant
frequency under the electrode and the frequency away from the
electroded region.

Also higher overtones are better polished and more sensitive to
parallelism.

Overtones pull less approx pulling of fundimental/overtone number
squared.



--
ddwyer

Found a source for 7360 and it is some interest among my friends for
using this tube in HF receivers, particularly for 80 and 40m
It was mentioned an article by W2PUL(?) in QST using a high current
twin triode as RF amplifier.
Have seen the SSR-1 rx schematics. Is some more notes available on
some sites for a modern version of receiver using these devices? I
suspect some parts of the receiver could be improved over the practice
used in the 60's
Any suggestions?

73
----
Jan-Martin, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/

Found a source for 7360 and it is some interest among my friends for
using this tube in HF receivers, particularly for 80 and 40m
It was mentioned an article by W2PUL(?) in QST using a high current
twin triode as RF amplifier.
Have seen the SSR-1 rx schematics. Is some more notes available on
some sites for a modern version of receiver using these devices? I
suspect some parts of the receiver could be improved over the practice
used in the 60's
Any suggestions?

73
----
Jan-Martin, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/

"ddwyer" wrote in message
...
In article j5M_b.5335$AL.133044@attbi_s03, Harold E. Johnson
writes

Hi Doug. I'm having mail bounce again going to you, new address, thought you
might want to know. Looks like maybe, the newsgroup is the most reliable way
to communicate!

Regards

W4ZCB

"ddwyer" wrote in message
...
In article j5M_b.5335$AL.133044@attbi_s03, Harold E. Johnson
writes

Hi Doug. I'm having mail bounce again going to you, new address, thought you
might want to know. Looks like maybe, the newsgroup is the most reliable way
to communicate!

Regards

W4ZCB

"Jan-Martin Noeding, LA8AK" ) writes:
Found a source for 7360 and it is some interest among my friends for
using this tube in HF receivers, particularly for 80 and 40m
It was mentioned an article by W2PUL(?) in QST using a high current
twin triode as RF amplifier.
Have seen the SSR-1 rx schematics. Is some more notes available on
some sites for a modern version of receiver using these devices? I
suspect some parts of the receiver could be improved over the practice
used in the 60's
Any suggestions?

The latest article I can think of seeing in print was February 1972.
I may have the date wrong. It was by one of the QST staff members
but not Doug DeMaw; I want to say Doug Blakeslee.

It was a 3.5MHz receiver with a 455KHz design, hardly cutting edge.
But it was intended for strong signal handling, so he used a tube
in the RF stage that had higher current handling. He half jokingly
suggested using an 807 in that stage.

A lot of those articles using the 7360 used no RF stage, which is
why you often saw a signal frequency Q-multiplier, to aid in image
recection. Of course, by the time the 7360 was put to use, HF range
IF filters were available so many of the receivers used an IF in
the 5 or 9MHz range.

Ray Moore had some articles in Ham Radio in 1972 and 1973 about
receiver design, and the introductory piece covered mixers including
the 7360, and then he had a "construction" article on a fancy AM
BCB receiver, that used a 7360.

Maybe some work was done with the mixer after that, but it pretty much
faded from view from that point on.

Michael VE2BVW

"Jan-Martin Noeding, LA8AK" ) writes:
Found a source for 7360 and it is some interest among my friends for
using this tube in HF receivers, particularly for 80 and 40m
It was mentioned an article by W2PUL(?) in QST using a high current
twin triode as RF amplifier.
Have seen the SSR-1 rx schematics. Is some more notes available on
some sites for a modern version of receiver using these devices? I
suspect some parts of the receiver could be improved over the practice
used in the 60's
Any suggestions?

The latest article I can think of seeing in print was February 1972.
I may have the date wrong. It was by one of the QST staff members
but not Doug DeMaw; I want to say Doug Blakeslee.

It was a 3.5MHz receiver with a 455KHz design, hardly cutting edge.
But it was intended for strong signal handling, so he used a tube
in the RF stage that had higher current handling. He half jokingly
suggested using an 807 in that stage.

A lot of those articles using the 7360 used no RF stage, which is
why you often saw a signal frequency Q-multiplier, to aid in image
recection. Of course, by the time the 7360 was put to use, HF range
IF filters were available so many of the receivers used an IF in
the 5 or 9MHz range.

Ray Moore had some articles in Ham Radio in 1972 and 1973 about
receiver design, and the introductory piece covered mixers including
the 7360, and then he had a "construction" article on a fancy AM
BCB receiver, that used a 7360.

Maybe some work was done with the mixer after that, but it pretty much
faded from view from that point on.

Michael VE2BVW

"Michael Black" wrote in message
...
"Jan-Martin Noeding, LA8AK" ) writes:
Found a source for 7360 and it is some interest among my friends for
using this tube in HF receivers, particularly for 80 and 40m
It was mentioned an article by W2PUL(?) in QST using a high current
twin triode as RF amplifier.
Have seen the SSR-1 rx schematics. Is some more notes available on
some sites for a modern version of receiver using these devices? I
suspect some parts of the receiver could be improved over the practice
used in the 60's
Any suggestions?

A couple, With Colin Horrabin's "H" mode mixer and the later switch mode
mixers available for well under a buck, the mixer has been removed from
being the concern it once was in receiver design. Since that topology, and
the 4066/312X/500X solid state mixers yield better linearity than the
following filters do, why return to the 7360? It was a fine mixer in it's
day. That day is LONG past. Try operating a 7360 in any close proximity to a
flourescent ballast. It will quickly disallusion you as to it's relative
worth except as a curiosity. Vacuum tube receiver technology and modern is
an oxymoron.

W4ZCB