On Tue, 27 Aug 2013, gareth wrote:

"Percy Picacity" wrote in message
...
In article ,
"gareth" wrote:

But the fact remains that for those who understand the use of a crystal
phasing control in pre-1950
receivers that the questions as posed above are as completely informative
as
is necessary.
And you have had your answer - the tuning of the BFO has no effect on
the phasing control and vice versa. Do you not believe the answer?

Stating the bleeding obvious which we all knew any way is about as useful
and as relevant as quoting Newton's laws of motion; for neither are an
appropriate
response to the query as originally put.

I refer you page 79 of the previously mentioned book.

I don't remember a book being mentioned.

Do a search on lamb "crystal filter" and you'll find at least one
article from the thirties where he describes the filter in depth. II
doubt the famous QST article from around that time covers the filter in
the same depth.

Michael

"Michael Black" wrote in message
ample.org...
On Tue, 27 Aug 2013, gareth wrote:

I refer you page 79 of the previously mentioned book.

I don't remember a book being mentioned.


11th edition of "Radio Handbook", 1947 edition (with endpaper adverts
for 1948) pub, Editos and Engineers Ltd, of Santa Barbara, Cal.

Those who claim that single-signal reception is due solely to the series
resonant peak
of the Xtal are quite wrong, because otherwies there'd be no need whatsoever
for
a notch facility.

This is what you should end up with ...

Wanted signal in the peak of series resonance.

Bfo adjusted on the HF side to give a pleasant tone.

Notch moved using the phasing control to be at the IF frequency that would
produce
the audio image from the current BFO setting.

What I was after was the procedure to set the notch frequency, because
unless you have a narrow
CW filter in the AF strip, how would you judge that you'd created the same
AF heterodyne whistle?

TKS FER heads-up on Lamb, I'll follow that.

In article ,
"gareth" wrote:

snip

Wanted signal in the peak of series resonance.

Bfo adjusted on the HF side to give a pleasant tone.

Notch moved using the phasing control to be at the IF frequency that would
produce
the audio image from the current BFO setting.

What I was after was the procedure to set the notch frequency, because
unless you have a narrow
CW filter in the AF strip, how would you judge that you'd created the same
AF heterodyne whistle?

TKS FER heads-up on Lamb, I'll follow that.


You judge it by listening. If there isn't an interfering signal at that
frequency you don't have to do anything and you don't care where the
notch is (unless you use it to suppress a signal at a different
frequency which is probably less of a nuisance as the beat note is
different). You only have to adjust the notch if there is an
interfering signal, and you adjust it to make the desired signal easier
to read. If the phasing control makes no audible difference, or there
isn't any QRM, don't bother with it.

--

Percy Picacity