"Percy Picacity" wrote in message
...
In article ,
"gareth" wrote:
snip
You're still missing the point that in addition to the peak response,
there
is
also a deep null.
No I'm not! It can be adjusted with the 'phase' control to null a signal
*at IF* near to the wanted one. Adjusting the position of the null has
no affect on beat frequency with the wanted signal, or the beat
frequency of the unwanted signal (it gives the BFO a less strong IF
interfering signal to beat with but it does not affect the frequency of
the beat note, just the loudness). Tuning the BFO has no effect on the
null. The two controls do not interact, though they both have an affect
on readability.


Straw Man

On 8/25/2013 7:09 PM, gareth wrote:
"Percy Picacity" wrote in message
...
In article ,
"gareth" wrote:
snip
You're still missing the point that in addition to the peak response,
there
is
also a deep null.
No I'm not! It can be adjusted with the 'phase' control to null a signal
*at IF* near to the wanted one. Adjusting the position of the null has
no affect on beat frequency with the wanted signal, or the beat
frequency of the unwanted signal (it gives the BFO a less strong IF
interfering signal to beat with but it does not affect the frequency of
the beat note, just the loudness). Tuning the BFO has no effect on the
null. The two controls do not interact, though they both have an affect
on readability.


Straw Man



To call you an idiot would be an insult to idiots everywhere.

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

On Sun, 25 Aug 2013, Percy Picacity wrote:

In article ,
"gareth" wrote:
snip

You're still missing the point that in addition to the peak response, there
is
also a deep null.

No I'm not! It can be adjusted with the 'phase' control to null a signal
*at IF* near to the wanted one. Adjusting the position of the null has
no affect on beat frequency with the wanted signal, or the beat
frequency of the unwanted signal (it gives the BFO a less strong IF
interfering signal to beat with but it does not affect the frequency of
the beat note, just the loudness). Tuning the BFO has no effect on the
null. The two controls do not interact, though they both have an affect
on readability.

I dug up an early article by Lamb about the filter (not the QST article
but some other publication). And there doesn't even have to be a notch.
Ajust the control a certain way and there's no notch, it's just a very
narrow filter.

The notch is just iciing on the cake, the filter was there to get a narrow
enough bandwidth so the audio image isn't there. There were some
construciton articles in the sixties in various magazines for adding cw
selectivity to SSB transceivers, which of course at the time often had
only an SSB suitable IF filter. And one scheme was to gang a few of those
phasing type filters, the ganging narrowed the skirt. SO they'd use
triodes, the crystal from the plate of one to the grid of the next, the
phasing capacitor from the cathode of one to the grid of the next, the
triode acting as a phase inverter instead of the transformer. And while
there were trimmer capacitors in each section so they could all be
aligned, no phasing control was brought to the front panel.

I said I never used the phasing control on the Sp-600, and one of these
days when I get my $20 at a garage sale TMC GPR-90 going (I don't think it
needs much work, I just need to get around to it), I doubt I'll use the
phasing control on it. The description of such filters always sounded to
me like the notch ability wasn't so useful, since it interacted with the
peaking of the actual crystal filter. It's not like having a separate
notch filter to wipe out offending interference. Circa 1936, the phasing
control probably helped a lot, all the receivers fairly simple and nobody
wanting to make things complicated in circuit or price, and of course the
bands weren't as crowded. But nowadays, it is something from the 1930s.
A great thing when you need a simple crystal filter, or to start with to
get the receiver going (and then replace with a better filter), but there
are better schemes out there already.

Michael VE2BVW

Jerry Stuckle wrote:
On 8/25/2013 7:09 PM, gareth wrote:
"Percy Picacity" wrote in message
...
In article ,
"gareth" wrote:
snip
You're still missing the point that in addition to the peak response,
there
is
also a deep null.
No I'm not! It can be adjusted with the 'phase' control to null a signal
*at IF* near to the wanted one. Adjusting the position of the null has
no affect on beat frequency with the wanted signal, or the beat
frequency of the unwanted signal (it gives the BFO a less strong IF
interfering signal to beat with but it does not affect the frequency of
the beat note, just the loudness). Tuning the BFO has no effect on the
null. The two controls do not interact, though they both have an affect
on readability.


Straw Man



To call you an idiot would be an insult to idiots everywhere.

Subscribe to ukra for a few weeks and you'll soon see that this is quite
lucid for Gareth. Wait till he gets going on the RSGB or the British tiered
licencing scheme...

--
If the above message is full of spelling mistakes or the snipping is duff,
it's probably because it was sent from my iPhone, likely whilst walking.
Apologies!

"gareth" wrote in message
...
"Peter Able" stuck@home wrote in message
o.uk...
*peak the wanted signal, adjust the BFO to give the optimum audio
frequency while adjusting phasing for maximum readability.


What do you mean by, "adjusting phasing for maximum readability", if the
signal is already
peaked at the series resonant frequency?

If you need to ask this question, I think that you would benefit from
directed experience of working with this sort of filter. Remember, we are
talking Readability, not Strength.

And where do you derive your opinion that this is normal?

From my lengthy experience as a successful professional engineer and from
holding a licence - Amateur (Sound) A and its successors - for many more
years than yourself. Also from what ability I have to assess and learn from
the opinions of others.


You asked for input from "experienced and senior" folk and yet you've been
rude and dismissive of such input. Why do you act down to Mr. Reay's
earlier characterisation of yourself? I'd like to see him proved wrong -
but that is a matter entirely in your hands, Gareth.

PA

On 26/08/2013 09:48, Peter Able wrote:
"gareth" wrote in message
...
"Peter Able" stuck@home wrote in message
o.uk...
*peak the wanted signal, adjust the BFO to give the optimum audio
frequency while adjusting phasing for maximum readability.


What do you mean by, "adjusting phasing for maximum readability", if the
signal is already
peaked at the series resonant frequency?

If you need to ask this question, I think that you would benefit from
directed experience of working with this sort of filter. Remember, we are
talking Readability, not Strength.

And where do you derive your opinion that this is normal?

From my lengthy experience as a successful professional engineer and from
holding a licence - Amateur (Sound) A and its successors - for many more
years than yourself. Also from what ability I have to assess and learn from
the opinions of others.


You asked for input from "experienced and senior" folk and yet you've been
rude and dismissive of such input. Why do you act down to Mr. Reay's
earlier characterisation of yourself? I'd like to see him proved wrong -
but that is a matter entirely in your hands, Gareth.

PA


Oh dear Peter, don't be surprised if your employer is added to the list
who receives an Email.

I've copies of several so far. If you need advice on how to proceed when
it happens, feel free to contact me.

A single crystal-plus-phasing-control is NOT a bandpass filter. It is
a SINGLE crystal that has a series-resonant peak and a parallel-resonant
notch, and it is most certainly not a symmetrical response curve.

The phasing control affects the frequency of the parallel-resonant notch.

The reason for my query is that googling threw up the instructions for
a Hallicrafters (SX42, I think) that suggested that the BFO could be
adjusted
AFTER the setting of the phasing control, when it seemed to me that such
action
would move the position of the notch AWAY from the audio image and thus
lost the single-signal facility.

But thanks for your contribution.



Gareth,

The answer is quite simple; unless you move the VFO there will be no
need to change the BFO setting. Adjusting the phasing control is akin to
an IF shift control on a modern radio with the addition of a notch to
the side of the passband which you can move with the phasing control.
Adjusting it will have no effect on the frequency of the received signal
merely the range of frequencies in the passband or the notch.


The only reason that the BFO might need adjusting is pulling of the VFO
which was quite common on early receivers due to poor supply regulation
and the like.

73
Jeff

On Sun, 25 Aug 2013 10:57:47 -0400, Jerry Stuckle wrote:

ROFLMAO. I would have loved to see that!

You should know that nearly everyone in ukra has a colourful past, some
more recent than others, some abusive, some not, as you will see if you
check out the postings of the person you are replying to.

More laughing guarranteed.



--
M0WYM
Sales @ radiowymsey
http://stores.ebay.co.uk/Sales-At-Radio-Wymsey/
http://sales-at-radio-wymsey.ebid.net/

Gareth Alun Evans G4SDW has quite the colourful past history in
uk.radio.amateur. If you fancy a good laugh, have a delve through the
Google Groups archive. It will not surprise you to learn that his
behaviour
at one point eventually resulted in a police officer standing on his head.


I blame the masons...never mind the polis man probably paid dearly for
believing what another mason probably told him ......

Wymsey wrote:
On Sun, 25 Aug 2013 10:57:47 -0400, Jerry Stuckle wrote:

ROFLMAO. I would have loved to see that!

You should know that nearly everyone in ukra has a colourful past, some
more recent than others, some abusive, some not, as you will see if you
check out the postings of the person you are replying to.

More laughing guarranteed.


Indeed. The pirate 2E0WYM here, for example, is masquerading as a full
licensee, having avoided training to the correct standard by fortuitously
"finding" and cashing in an allegedly 40 year old RAE pass certificate to
dodge the current, rigorous Full Licence exam.

--
If the above message is full of spelling mistakes or the snipping is duff,
it's probably because it was sent from my iPhone, likely whilst walking.
Apologies!