gareth wrote:
"Peter Able" stuck@home wrote in message
IMHO, Peter's reply is the correct opening statement of a response to your
rather unstructured question. If you cannot then use this statement to
seed and to refine your own thought process, it might be more helpful if
you elaborated the point that you think he is missing.

Thanks. but the subject matter seems to have WHOOSHED over your head.

Mine too, I don't really understand what you're asking. The crystal filter
is a bandpass filter. The phasing control affects the symmetry of the
filter somewhat (but not really all that much).
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In message , Scott Dorsey
writes
gareth wrote:
"Peter Able" stuck@home wrote in message
IMHO, Peter's reply is the correct opening statement of a response to your
rather unstructured question. If you cannot then use this statement to
seed and to refine your own thought process, it might be more helpful if
you elaborated the point that you think he is missing.

Thanks. but the subject matter seems to have WHOOSHED over your head.

Mine too, I don't really understand what you're asking. The crystal filter
is a bandpass filter. The phasing control affects the symmetry of the
filter somewhat (but not really all that much).
--scott

The crystal by itself has a natural 'blow-suck' signal throughput, with
a sharp notch just HF of the peak. The phasing control capacitor should
be able to move the notch to the LF side of the peak, and also (to a
limited extent) to move the notch a little closer to the peak (on either
side).
--
Ian

"Ian Jackson" wrote in message
...
In message , Scott Dorsey
writes
gareth wrote:
"Peter Able" stuck@home wrote in message
IMHO, Peter's reply is the correct opening statement of a response to
your
rather unstructured question. If you cannot then use this statement to
seed and to refine your own thought process, it might be more helpful
if
you elaborated the point that you think he is missing.

Thanks. but the subject matter seems to have WHOOSHED over your head.

Mine too, I don't really understand what you're asking. The crystal
filter
is a bandpass filter. The phasing control affects the symmetry of the
filter somewhat (but not really all that much).
--scott

The crystal by itself has a natural 'blow-suck' signal throughput, with a
sharp notch just HF of the peak. The phasing control capacitor should be
able to move the notch to the LF side of the peak, and also (to a limited
extent) to move the notch a little closer to the peak (on either side).

Ian, with your greater experience than mine, it is the concept of
single-signal reception in which I am interested.

Have you any clues about that, please?

In message , gareth
writes
"Ian Jackson" wrote in message
...
In message , Scott Dorsey
writes
gareth wrote:
"Peter Able" stuck@home wrote in message
IMHO, Peter's reply is the correct opening statement of a response to
your
rather unstructured question. If you cannot then use this statement to
seed and to refine your own thought process, it might be more helpful
if
you elaborated the point that you think he is missing.

Thanks. but the subject matter seems to have WHOOSHED over your head.

Mine too, I don't really understand what you're asking. The crystal
filter
is a bandpass filter. The phasing control affects the symmetry of the
filter somewhat (but not really all that much).
--scott

The crystal by itself has a natural 'blow-suck' signal throughput, with a
sharp notch just HF of the peak. The phasing control capacitor should be
able to move the notch to the LF side of the peak, and also (to a limited
extent) to move the notch a little closer to the peak (on either side).

Ian, with your greater experience than mine, it is the concept of
single-signal reception in which I am interested.

Have you any clues about that, please?

The only clue I can offer is that 'single-signal reception' is vague -
but presumably self-explanatory, ie the filtering is very narrow,
enabling you to receive only one signal (unless you have more than one
on or very close to the same frequency). It's a term that I recall being
around when I were a lad, but I can't say I've heard it much since. I
guess it's been replaced by more scientific descriptions of how good the
filtering is.
--
Ian

"Ian Jackson" wrote in message
...

Ian, with your greater experience than mine, it is the concept of
single-signal reception in which I am interested.

Have you any clues about that, please?

The only clue I can offer is that 'single-signal reception' is vague - but
presumably self-explanatory, ie the filtering is very narrow, enabling you
to receive only one signal (unless you have more than one on or very close
to the same frequency). It's a term that I recall being around when I were
a lad, but I can't say I've heard it much since. I guess it's been
replaced by more scientific descriptions of how good the filtering is.

Thank you, Ian. I have a vague memory of something in BadCon from about 40
years ago which
related to setting up for single signal reception, which involved no further
adjustments to phasing or BFO once it had been set. I am fairly sure, hence
my
enquiry that it involved phasing out the audio image as well as involving
the peaking
that comes from a single series resonant crystal.

Hence my assumption that the BFO frequency must lie half way between the
peak and the notch.

I've no experience of such things. The HRO I had in my possession 20 years
ago did not posses
the crystal filter, but in an effort to speed up development of my RX
project, it seemed to me
that a single crystal filter would be an easier starting point than a ladder
filter.

In message , gareth
writes
"Ian Jackson" wrote in message
...

Ian, with your greater experience than mine, it is the concept of
single-signal reception in which I am interested.

Have you any clues about that, please?

The only clue I can offer is that 'single-signal reception' is vague - but
presumably self-explanatory, ie the filtering is very narrow, enabling you
to receive only one signal (unless you have more than one on or very close
to the same frequency). It's a term that I recall being around when I were
a lad, but I can't say I've heard it much since. I guess it's been
replaced by more scientific descriptions of how good the filtering is.

Thank you, Ian. I have a vague memory of something in BadCon from about 40
years ago which
related to setting up for single signal reception, which involved no further
adjustments to phasing or BFO once it had been set. I am fairly sure, hence
my
enquiry that it involved phasing out the audio image as well as involving
the peaking
that comes from a single series resonant crystal.

Hence my assumption that the BFO frequency must lie half way between the
peak and the notch.

I've no experience of such things. The HRO I had in my possession 20 years
ago did not posses
the crystal filter, but in an effort to speed up development of my RX
project, it seemed to me
that a single crystal filter would be an easier starting point than a ladder
filter.

You're not confusing SSB generation (and reception) by the 'phasing
method', are you? That requires something quite different from the
action of the elementary single crystal filter we're talking about.

While a single crystal filter can provide a fair amount of selectivity
(combined, if you choose to use it, useful suck-blow or blow-suck
frequency response), it is not really suitable for 'serious' SSB
filtering. Its frequency selectivity characteristics don't really use
clever phasing out of the audio image. The passband peak is really too
sharp for either the generation or reception of good quality SSB, and
you usually need a 'proper' flat-topped filter, a 'proper' SSB phasing
TX or RX (which also does exist in a direct-conversion form) - or if
you're really clever, a 'third method' phasing TX (or, I suppose, RX).
That said, I'm sure that 'KISS' transmitters and receivers have been
made using a single-crystal filter - albeit having a somewhat limited
performance.
--
Ian

"Ian Jackson" wrote in message
...

You're not confusing SSB generation (and reception) by the 'phasing
method', are you?

Neither that nor Weaver's Third Method.


While a single crystal filter can provide a fair amount of selectivity
(combined, if you choose to use it, useful suck-blow or blow-suck
frequency response), it is not really suitable for 'serious' SSB
filtering. Its frequency selectivity characteristics don't really use
clever phasing out of the audio image. The passband peak is really too
sharp for either the generation or reception of good quality SSB, and you
usually need a 'proper' flat-topped filter, a 'proper' SSB phasing TX or
RX (which also does exist in a direct-conversion form) - or if you're
really clever, a 'third method' phasing TX (or, I suppose, RX).

Actually easier to set up for the Third Method, because all the phasing is
done
at a single audio frequency. But that's not what this thread is about.


That said, I'm sure that 'KISS' transmitters and receivers have been made
using a single-crystal filter - albeit having a somewhat limited
performance.

It's not for SSB. CW forever!

However, ISTR G3VA (RIP) in his TT column discussing Stenode
correction when trying to resolve voice through a single-Xtal filter.

Ian Jackson wrote:
In message , Scott Dorsey writes:

Mine too, I don't really understand what you're asking. The crystal
filter
is a bandpass filter. The phasing control affects the symmetry of the
filter somewhat (but not really all that much).

The crystal by itself has a natural 'blow-suck' signal throughput, with a
sharp notch just HF of the peak. The phasing control capacitor should be
able to move the notch to the LF side of the peak, and also (to a limited
extent) to move the notch a little closer to the peak (on either side).

Yes, and that notch is useful for eliminating a single interfering CW
signal. But it's not useful for multiple interfering signals or much
at all for SSB.

"Single signal reception" to me would imply a narrow-sloped bandpass
filter but it sounds more like marketing than engineering.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Scott Dorsey" wrote in message
...
Ian Jackson wrote:
In message , Scott Dorsey writes:

Mine too, I don't really understand what you're asking. The crystal
filter
is a bandpass filter. The phasing control affects the symmetry of the
filter somewhat (but not really all that much).

The crystal by itself has a natural 'blow-suck' signal throughput, with a
sharp notch just HF of the peak. The phasing control capacitor should be
able to move the notch to the LF side of the peak, and also (to a limited
extent) to move the notch a little closer to the peak (on either side).

Yes, and that notch is useful for eliminating a single interfering CW
signal. But it's not useful for multiple interfering signals or much
at all for SSB.

"Single signal reception" to me would imply a narrow-sloped bandpass
filter but it sounds more like marketing than engineering.

Perhaps you, as indeed do others seem, are trying to interpret a technique
from
the 1930s and 1940s in terms of the multi-pole Xtal filters that are the
norm today?

gareth wrote:
"Scott Dorsey" wrote in message

"Single signal reception" to me would imply a narrow-sloped bandpass
filter but it sounds more like marketing than engineering.

Perhaps you, as indeed do others seem, are trying to interpret a technique
from
the 1930s and 1940s in terms of the multi-pole Xtal filters that are the
norm today?

Well, yes. That is the point of this thread, isn't it?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."