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APF For K3

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Laurent F6DEX

Re: APF For K3: progress report

HI Wayne

For additional commands, you can still use CAT commands and each user choose how he uses the macros functions and reallocates each button... At least, this way, you are not limited in the number of functions.

Yes, probably the XFIL/Dual PB is a good candidate for APF. Now the logic is up to you !

73, Laurent

Laurent F6DEX

Guy, K2AV

Re: APF For K3: progress report

In reply to this post by wayne burdick

If you do it this way, how would you use it inside the 400 Hz roofing
filter, where you wanted it to diminish somewhat toward the skirts of
the roofer and then dive down. There would be no way of having this
happen inside a given roofing filter other than the narrowest as the
roofer is implied by the width setting.

Would not be of any use at all on a running frequency. This only
works as peak shaped audio to further narrow the very narrowest DSP
selectivity. Personally I've never been disappointed by the 50 Hz,
which is the cleanest narrow I've ever had in a RX.

Not at all what I had in mind. With 400 Hz bandwidth and 500 Hz
center, the passband INSIDE the roofer skirts is peaked at 500, loses
about 10 db going down to 300 and up to 700, and at 300 and 700 does
the normal roofer/DSP skirt sharp dive.

This allows me to HEAR the off-freq caller, and either shift or RIT to
center him, without the noise burden of a flat 400 Hz. Using the NR
for this in a contest masks or loses really weak signals. Not yet
discovered a setting that doesn't take away more than it gives. Never
use NR on CW at NY4A on our K3's. Lose the whisper contacts just in
the noise, any NR setting. Wouldn't even know they were there.

Perhaps for this need a special NR setting that only shapes the audio
without any cancellation at the noise level and several degrees of
slope off?

This is what I always meant by APF.

Just my .02

73, Guy.

On Mon, Oct 25, 2010 at 2:39 PM, Wayne Burdick <[hidden email]> wrote:

> We might have a field-test revision of K3 code that includes APF
> sometime this week.
>
> In this test version, APF is turned on by rotating the WIDTH control
> counterclockwise past the 50-Hz setting ("BW 0.05") to the 30-Hz APF
> setting ("APF 0.03"). This eliminates the need for a menu entry or a
> new switch function. A new DSP graphic pattern shows that APF is in
> effect. SHIFT can be used, with either 10- or 50-Hz steps.
>
> The APF filter is an "IIR" (infinite impulse response) DSP filter that
> accurately emulates the equivalent analog circuitry. There's a slight
> ring to the filter, as expected. Gain is also increased when APF is
> turned on, compensating for the loss of overall signal+noise that
> occurs at this very narrow bandwidth.
>
> 73,
> Wayne
> N6KR
>
> ______________________________________________________________
> Elecraft mailing list
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P.B. Christensen

Re: APF For K3: progress report

In reply to this post by wayne burdick

Wayne,

I like the idea of engaging APF independent of DSP or roofing bandwidth.
There are times on an open band where APF can be effective without the need
to mitigate interference through the use of roofing filters, thereby
minimizing through-loss.

A long press of Dual PB or use of 'Notch' in CW as W4TV points out seem like
reasonable methods to engage the APF feature.

Paul, W9AC

----- Original Message -----
From: "Wayne Burdick" <[hidden email]>
To: "Joe Subich, W4TV" <[hidden email]>
Cc: <[hidden email]>
Sent: Monday, October 25, 2010 4:30 PM
Subject: Re: [Elecraft] APF For K3: progress report

> Joe,
>
> We're still experimenting with both the UI and the underlying filter
> function. I jumped the gun a bit in my proposed use of the WIDTH
> control to activate APF, and we're looking at other ways to do that so
> that the width can still be set independently.
>
> One possibility is to overload the DUAL PB control (say, a long hold
> of DUAL PB turns on APF, or the DUAL PB control has three settings).
> When APF is selected, the SHIFT control could adjust the APF center
> frequency, leaving the rig's normal passband unshifted.
>
> More later--
>
> Wayne
>
> ______________________________________________________________
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Jim Brown-10

Re: APF For K3

In reply to this post by Merv Schweigert

On 10/25/2010 12:29 PM, Merv Schweigert wrote:
> but never found them useful for CW. The filter in my head always seems better at picking out the desired signal than the audio filter

That's usually been my experience too, primarily because the skirts ring
on QRN, and the narrower the filter, the closer those skirts get to the
CW note. The closer the ringing is to the CW note, the harder it is for
the ear/brain to separate them. This is pretty well known by scientists
working in the psychoacoustic world.

73, Jim K9YC
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The Smiths

Re: APF For K3: progress report

In reply to this post by Guy, K2AV

Anyone that has ever used the FT-1000 or the the FT-2000 knows exactly what the APF (or Contour setting as they call it) can do. It's an AMAZING tool to have in your tool box. With the FT-2000 you could choose whether you were going to Peak or Dip at the Contour freq. Furthermore, You could keep your filters set to ANY width you wanted to, and simultaneously Dip or Peak within the "Contour" / APF area. If you need any ideas on how this function should work than just refer to an FT-2000 or perhaps even an FT-5000 rig. It's very plain simple and clear. Which button it's put on is pretty much a "who cares", so long as it works.
As for the NR, I use that ALL the time, and I find that in my QTH it's a MUST have. There's FAR too much noise where I live, and with a constant S3 to S5 noise floor on 30 meters I rely HEAVILY on the NR to help me make things work out. The NB works well for me too, but the NR is far more important. I can only wish that I were one of you guys that lives where you have a perfect S1 noise floor and don't need your NR to work.
I've not once missed a weak signal using my NR by the way, because I know how to use it in conjunction with the RF gain and proper (for me) AGC settings.

> Date: Mon, 25 Oct 2010 17:01:14 -0400
> From: [hidden email]
> To: [hidden email]
> CC: [hidden email]; [hidden email]
> Subject: Re: [Elecraft] APF For K3: progress report
>
> If you do it this way, how would you use it inside the 400 Hz roofing
> filter, where you wanted it to diminish somewhat toward the skirts of
> the roofer and then dive down. There would be no way of having this
> happen inside a given roofing filter other than the narrowest as the
> roofer is implied by the width setting.
>
> Would not be of any use at all on a running frequency. This only
> works as peak shaped audio to further narrow the very narrowest DSP
> selectivity. Personally I've never been disappointed by the 50 Hz,
> which is the cleanest narrow I've ever had in a RX.
>
> Not at all what I had in mind. With 400 Hz bandwidth and 500 Hz
> center, the passband INSIDE the roofer skirts is peaked at 500, loses
> about 10 db going down to 300 and up to 700, and at 300 and 700 does
> the normal roofer/DSP skirt sharp dive.
>
> This allows me to HEAR the off-freq caller, and either shift or RIT to
> center him, without the noise burden of a flat 400 Hz. Using the NR
> for this in a contest masks or loses really weak signals. Not yet
> discovered a setting that doesn't take away more than it gives. Never
> use NR on CW at NY4A on our K3's. Lose the whisper contacts just in
> the noise, any NR setting. Wouldn't even know they were there.
>
> Perhaps for this need a special NR setting that only shapes the audio
> without any cancellation at the noise level and several degrees of
> slope off?
>
> This is what I always meant by APF.
>
> Just my .02
>
> 73, Guy.
>
> On Mon, Oct 25, 2010 at 2:39 PM, Wayne Burdick <[hidden email]> wrote:
> > We might have a field-test revision of K3 code that includes APF
> > sometime this week.
> >
> > In this test version, APF is turned on by rotating the WIDTH control
> > counterclockwise past the 50-Hz setting ("BW 0.05") to the 30-Hz APF
> > setting ("APF 0.03"). This eliminates the need for a menu entry or a
> > new switch function. A new DSP graphic pattern shows that APF is in
> > effect. SHIFT can be used, with either 10- or 50-Hz steps.
> >
> > The APF filter is an "IIR" (infinite impulse response) DSP filter that
> > accurately emulates the equivalent analog circuitry. There's a slight
> > ring to the filter, as expected. Gain is also increased when APF is
> > turned on, compensating for the loss of overall signal+noise that
> > occurs at this very narrow bandwidth.
> >
> > 73,
> > Wayne
> > N6KR
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> >
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html

The Smiths

Re: APF For K3

In reply to this post by Jim Brown-10

By the way, the 50Hz filter on the K3 is really about 80 Hz wide, not 50... If you turn on the iir filter (in the config menu) THAN you can see it squeeze down to about 50 or 60Hz width. This could be why the K3 sounds so much cleaner at such narrow width settings than other rigs. I'm not really sure that it should say 50 Hz on the display unless the iir is turned on along with it. Just my opinion.

> Date: Mon, 25 Oct 2010 14:17:15 -0700
> From: [hidden email]
> To: [hidden email]
> Subject: Re: [Elecraft] APF For K3
>
> On 10/25/2010 12:29 PM, Merv Schweigert wrote:
> > but never found them useful for CW. The filter in my head always seems better at picking out the desired signal than the audio filter
>
> That's usually been my experience too, primarily because the skirts ring
> on QRN, and the narrower the filter, the closer those skirts get to the
> CW note. The closer the ringing is to the CW note, the harder it is for
> the ear/brain to separate them. This is pretty well known by scientists
> working in the psychoacoustic world.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

AC7AC

Re: APF For K3

In reply to this post by Jim Brown-10

CONTENTS DELETED

The author has deleted this message.

Dale Parfitt-3

Re: APF For K3

> When dealing with very weak signals in the absence of really strong QRM,
I

> use the widest bandwidth possible for just that reason. At least 2.8 kHz
> is
> typical for me and I almost never drop below 1 kHz. The more pink or
> white-ish the noise, the easier it is to hear a very weak CW signal down
> in
> it.
>
> That's why I vastly prefer the notch filter to help my gray matter filter
> in
> case a really strong signal appears in the bandpass.
>
> On stronger signals mixed in a lot of heavy QRM I'll crank in the
> bandwidth
> so the desired signal is the only one I hear. Then I can pretend I'm
> listening to a code practice oscillator - it sure doesn't sound like a
> "radio", Hi
>
> Now that Wayne's implementing APF I'm curious to see how it sounds. I'm
> prepared to be astonished if it sounds any different than a decent active
> audio filter with some gain at the center frequency.
>
> Ron AC7AC
>

Hi Ron,
A lot of my activity is on 1296MHz EME where the background noise is
extremely consistant. I found the APF on the IC-7700 to be useless, but
interestingly the audio peak function on my Alpha Delta VRC (Variable
Response Console) consistantly pulls weak CW signals out that the narrow
roofing and/or DSP filters do not.
Visitors to my station have noticed the same effect- and have gone searching
for a VRC for their EME station. Reports here on the reflector that it is
possible for an APF to function very well are encouraging- so I too look
forward to its implementation.

Dale W4OP

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n7ws

Re: APF For K3: progress report

In reply to this post by wayne burdick

OK. Next question; can I assume then that the TX and frequency readout follow?

--- On Mon, 10/25/10, Wayne Burdick <[hidden email]> wrote:

> It will in the K3 case. If you have
> SHIFT centered, the APF filter will be at your sidetone
> pitch. So in most cases you won't even need to do a SHIFT;
> just turn APF on using a full counterclockwise setting of
> the WIDTH control. SHIFT can be used if you want to tune in
> a station that is slightly off your sidetone pitch.
>
> Wayne
>
>

The Smiths

Re: APF For K3: progress report

What does APX have to do with TX or the readout? This is a Receive feature whereby it PEAKS a particular freq. in CW mode. The Shift number should read out JUST as it does now.. It would only effect the position of the APF location as you move it. This is my understanding.

Wayne, Although that sounds like a cleaver idea, sometimes you want to keep the shift off freq. from your center pitch, but still peak someone in. This can help reduce noise that is in your pitch Band pass, but alow you to de-tune the noise around it... This presents a problem for your idea. It means that there would have to be a separate knob for the Shift and the APF location. Or at least this is how it should be.

> Date: Mon, 25 Oct 2010 17:47:42 -0700
> From: [hidden email]
> To: [hidden email]
> CC: [hidden email]
> Subject: Re: [Elecraft] APF For K3: progress report
>
> OK. Next question; can I assume then that the TX and frequency readout follow?
>
> --- On Mon, 10/25/10, Wayne Burdick <[hidden email]> wrote:
>
>
> > It will in the K3 case. If you have
> > SHIFT centered, the APF filter will be at your sidetone
> > pitch. So in most cases you won't even need to do a SHIFT;
> > just turn APF on using a full counterclockwise setting of
> > the WIDTH control. SHIFT can be used if you want to tune in
> > a station that is slightly off your sidetone pitch.
> >
> > Wayne
> >
> >
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html

wayne burdick

Re: APF For K3: progress report

Administrator

In reply to this post by n7ws

Wes,

The TX and VFO frequencies won't behave any differently with APF
turned on, if that's what you're asking. They'll still be corrected
for your sidetone pitch, as always.

APF will behave like a tunable narrow filter superimposed on the
normal passband. Its initial frequency would match the sidetone pitch,
but you'll be able to move it around using the shift control.

We're still playing with it.

Wayne

On Oct 25, 2010, at 5:47 PM, Wes Stewart wrote:

> OK. Next question; can I assume then that the TX and frequency
> readout follow?
>
> --- On Mon, 10/25/10, Wayne Burdick <[hidden email]> wrote:
>
>
>> It will in the K3 case. If you have
>> SHIFT centered, the APF filter will be at your sidetone
>> pitch. So in most cases you won't even need to do a SHIFT;
>> just turn APF on using a full counterclockwise setting of
>> the WIDTH control. SHIFT can be used if you want to tune in
>> a station that is slightly off your sidetone pitch.
>>
>> Wayne
>>
>>
>
>
>

n7ws

Re: APF For K3: progress report

In reply to this post by wayne burdick

I understand completely what a BPF filter does, tunable or otherwise. You forget that this is a "transceiver", not a standalone receiver.

If, as I believe Wayne indicated, the "Pitch" (NOT Shift) is going to follow the peak frequency of the filter (as it should IMHO) then the transmitter better follow along if you want to answer a guy on his RX frequency.

If the transmitter is left behind, then if your nominal pitch is 500 Hz, then if you tune, for example, to a signal with a 700 Hz pitch, you're essentially operating split with a 200 Hz offset.

The frequency readout indicates the zero beat frequency, as can be seen by switching modes from CW to SSB. The readout will be different between the two modes by the pitch frequency.

If I'm off-base here and the APF can be tuned to other than the nominal pitch frequency (for reasons that totally escape me) then you will be operating "split". Bad form these days.

Wes

--- On Mon, 10/25/10, The Smiths
<[hidden email]> wrote:

What does APX have to do with TX or the readout? This is a Receive feature whereby it PEAKS a particular freq. in CW mode. The Shift number should read out JUST as it does now.. It would only effect the position of the APF location as you move it. This is my understanding.

Wayne, Although that sounds like a cleaver idea, sometimes you want to keep the shift off freq. from your center pitch, but still peak someone in. This can help reduce noise that is in your pitch Band pass, but alow you to de-tune the noise around it... This presents a problem for your idea. It means that there would have to be a separate knob for the Shift and the APF location. Or at least this is how it should be.

Elecraft mailing list
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n7ws

Re: APF For K3: progress report

In reply to this post by wayne burdick

Wayne,

Understood, but why would anyone want to have a filter peaked at other than the nominal sidetone pitch? I realize people are asking for it, but it makes zero sense to me.

Wes

--- On Mon, 10/25/10, Wayne Burdick <[hidden email]> wrote:

> Wes,
>
> The TX and VFO frequencies won't behave any differently
> with APF turned on, if that's what you're asking. They'll
> still be corrected for your sidetone pitch, as always.
>
> APF will behave like a tunable narrow filter superimposed
> on the normal passband. Its initial frequency would match
> the sidetone pitch, but you'll be able to move it around
> using the shift control.
>
> We're still playing with it.
>
> Wayne
>

Don Wilhelm-4

Re: APF For K3: progress report

In reply to this post by n7ws

Wes,

I agree with you - leave the pitch at the sidetone pitch and use the VFO
to tune the desired station to that pitch is the best solution.
However some operators do it differently. There are many adherents of
RIT and XIT. I understand their use for stations that are 'running',
but for normal QSOs it is not required on a transceiver that can shift
transmit frequency easily with the VFO knob. Zero-beat the station to
be in QSO with and take up less bandspace. If everyone operated like
that, there should be no need to change the pitch of the "peaking" point
- it would be whatever the sidetone pitch is set to.

73,
Don W3FPR

On 10/25/2010 9:38 PM, Wes Stewart wrote:

> I understand completely what a BPF filter does, tunable or otherwise. You forget that this is a "transceiver", not a standalone receiver.
>
> If, as I believe Wayne indicated, the "Pitch" (NOT Shift) is going to follow the peak frequency of the filter (as it should IMHO) then the transmitter better follow along if you want to answer a guy on his RX frequency.
>
> If the transmitter is left behind, then if your nominal pitch is 500 Hz, then if you tune, for example, to a signal with a 700 Hz pitch, you're essentially operating split with a 200 Hz offset.
>
> The frequency readout indicates the zero beat frequency, as can be seen by switching modes from CW to SSB. The readout will be different between the two modes by the pitch frequency.
>
> If I'm off-base here and the APF can be tuned to other than the nominal pitch frequency (for reasons that totally escape me) then you will be operating "split". Bad form these days.
>
> Wes
>

wayne burdick

Re: APF For K3: progress report

Administrator

In reply to this post by n7ws

For the same reason that they want to use SHIFT: because sometimes
stations call you off-frequency.

Wayne

On Oct 25, 2010, at 6:50 PM, Wes Stewart wrote:

> Wayne,
>
> Understood, but why would anyone want to have a filter peaked at
> other than the nominal sidetone pitch? I realize people are asking
> for it, but it makes zero sense to me.
>
> Wes
>
> --- On Mon, 10/25/10, Wayne Burdick <[hidden email]> wrote:
>
>> Wes,
>>
>> The TX and VFO frequencies won't behave any differently
>> with APF turned on, if that's what you're asking. They'll
>> still be corrected for your sidetone pitch, as always.
>>
>> APF will behave like a tunable narrow filter superimposed
>> on the normal passband. Its initial frequency would match
>> the sidetone pitch, but you'll be able to move it around
>> using the shift control.
>>
>> We're still playing with it.
>>
>> Wayne
>>
>
>
>
>

n7ws

Re: APF For K3: progress report

In reply to this post by Don Wilhelm-4

Don,

Finally someone who understands how transceivers work!

I use XIT and RIT all of the time in lieu of the split function. But that's on purpose and I understand the ramifications.

Thanks,

Wes

--- On Mon, 10/25/10, Don Wilhelm <[hidden email]> wrote:

From: Don Wilhelm <[hidden email]>
Subject: Re: [Elecraft] APF For K3: progress report
To: "Wes Stewart" <[hidden email]>
Cc: "Wayne Berdock" <[hidden email]>, "The Smiths" <[hidden email]>, "Elecraft Reflector" <[hidden email]>
Date: Monday, October 25, 2010, 7:57 PM

Wes,

I agree with you - leave the pitch at the sidetone pitch and use the VFO to tune the desired station to that pitch is the best solution.
However some operators do it differently. There are many adherents of RIT and XIT. I understand their use for stations that are 'running', but for normal QSOs it is not required on a transceiver that can shift transmit frequency easily with the VFO knob. Zero-beat the station to be in QSO with and take up less bandspace. If everyone operated like that, there should be no need to change the pitch of the "peaking" point - it would be whatever the sidetone pitch is set to.

73,
Don W3FPR

On 10/25/2010 9:38 PM, Wes Stewart wrote:

n7ws

Re: APF For K3: progress report

In reply to this post by wayne burdick

There's a button labeled "RIT" and an associated knob especially for that purpose.

--- On Mon, 10/25/10, Wayne Burdick <[hidden email]> wrote:

For the same reason that they want to use SHIFT: because sometimes
stations call you off-frequency.

Wayne

On Oct 25, 2010, at 6:50 PM, Wes Stewart wrote:

> Wayne,
>
> Understood, but why would anyone want to have a filter peaked at
> other than the nominal sidetone pitch? I realize people are asking
> for it, but it makes zero sense to me.
>
> Wes

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The Smiths

Re: APF For K3: progress report

Wes, I think that you're missing the point of what the shift knob does.. Yes, you can use the RIT to tune someone in but the Shift shifts your IF without moving your Transmit or Receive VFO position. This isn't about a tone, this is about the IF passband.

As for the need for separate IF shift and APF tuning, If I can answer for my self... I would want it to be separate to control noise, if it works anything like the Yaesu contour filter (when in peak mode) than it's very nice to be able to peak signals that aren't always exactly in the center of your IF passband. Not only does the Yaesu peak the center of the IF (pitch freq.) but it would also attenuate the noise floor around it. Therefore if I have noise in the center of the IF, and I want to shift away, I may still wish to move the peak to suppress the QRM along with it.
Sometimes you just have to try something to understand it. Being able to take the dial and swing it around with the APF on and hear what peaks and what suppresses will let you determine how you want to separate the IF pass band from the APF. It's not unlike how the manual Notch filter works. As you swing it around you can hear how it suppresses some signals below or above your IF passband.

Wayne, I would like to make my suggestion for where to place these controls. If it were up to me (with out giving it any more thought than I already have) I would like to see the "switch" to turn the APF on and off as a HOLD on the AFX button. If I'm not mistaken this button is un-used when in CW and SSB mode. Therefore if you hold the AFX button down in CW it could activate the "effect" of the APF... As for moving it's position, I was thinking that unless it's going to be used in SSB mode, you could place the centering position on the Comp/PWR knob. Put it in the place of COMP. Even if someone wanted to use it for SSB mode they probably already have their Compressor set up as they use it for their mic. I don't know that most people use their COMP control every time they get on SSB. I would think you set it up for that particular mic and leave it. This would make dual use of the Comp knob while still keeping the Width and Shift knobs operate as they already do. If i
t's possible to change the color of the LED I would switch it to Orange or blink when in the APF mode as an indicator that it's not working the COMP.

> Date: Mon, 25 Oct 2010 19:17:16 -0700
> From: [hidden email]
> To: [hidden email]
> CC: [hidden email]
> Subject: Re: [Elecraft] APF For K3: progress report
>
> There's a button labeled "RIT" and an associated knob especially for that purpose.
>
> --- On Mon, 10/25/10, Wayne Burdick <[hidden email]> wrote:
>
>
> For the same reason that they want to use SHIFT: because sometimes
> stations call you off-frequency.
>
> Wayne
>
> On Oct 25, 2010, at 6:50 PM, Wes Stewart wrote:
>
> > Wayne,
> >
> > Understood, but why would anyone want to have a filter peaked at
> > other than the nominal sidetone pitch? I realize people are asking
> > for it, but it makes zero sense to me.
> >
> > Wes
>
>
>
>
>
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P.B. Christensen

Re: APF For K3: progress report

In reply to this post by n7ws

> There's a button labeled "RIT" and an associated knob especially for that
> purpose.

Wes,

Here's an example of using APF in conjunction with RIT. I normally leave my
CW offset at 650 Hz. Some of my CW operating is very weak signal DX on the
low bands. When copying extremely weak DX in the midst of static crashes, I
need to temporarily shift pitch to less than 400 Hz. Some ops, including
W4ZV, have noted that weak CW copy can improve when low pitch is used. I
also don't want to tamper with my normal CW offset if I don't need to.

By engaging in RIT, I would like to temporally dip the incoming pitch, leave
my CW offset alone where I want it 95% of the time, and then adjust the
frequency of the APF to match/peak the incoming pitch selected by RIT. If I
want to experiment with different pitch settings based on band conditions, I
also want the ability for the APF peak to track the pitch I've selected on
RIT. That requires a tunable APF. This is precisely what the FT-1000/D
gave its users.

Of course, the greater the departure of the RIT pitch from the offset may
require a wider DSP filter setting and/or roofing filter. But under these
weak band conditions, wide DSP and roofing filters are just fine when band
activity and adjacent interference is low or moderate. When I'm working
early morning grayline DX on 80m or 40m, I rarely encounter strong adjacent
stations since conditions are long and stateside is not heard much of the
time. Because of this, my overall Rx bandwidth is generally set to 2.8 kHz
or greater. Even when weak DX is running split and listening up 2 kHz,
there's ample separation to allow a filter settings wide enough to depart a
few hundred Hz from the CW offset.

Paul, W9AC

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Andy Faber

Re: APF For K3: progress report

In reply to this post by n7ws

Wes,
If you are running on 160 or 80 in a contest and a weak signal calls you
slightly off frequency, it's handy on the FT1000D to move the apf freq
around to find him and enhance his signal. In theory you could do the same
with the RIT, but it can be easier to move the apf, particularly if there is
more than one weak signal. Maybe it's just personal preference, but I do
like that feature.
73, andy, ae6y

--------------------------------------------------
From: "Wes Stewart" <[hidden email]>
Sent: Monday, October 25, 2010 6:50 PM
To: "Wayne Burdick" <[hidden email]>
Cc: <[hidden email]>
Subject: Re: [Elecraft] APF For K3: progress report

> Wayne,
>
> Understood, but why would anyone want to have a filter peaked at other
> than the nominal sidetone pitch? I realize people are asking for it, but
> it makes zero sense to me.
>
> Wes
>
> --- On Mon, 10/25/10, Wayne Burdick <[hidden email]> wrote:
>
>> Wes,
>>
>> The TX and VFO frequencies won't behave any differently
>> with APF turned on, if that's what you're asking. They'll
>> still be corrected for your sidetone pitch, as always.
>>
>> APF will behave like a tunable narrow filter superimposed
>> on the normal passband. Its initial frequency would match
>> the sidetone pitch, but you'll be able to move it around
>> using the shift control.
>>
>> We're still playing with it.
>>
>> Wayne
>>
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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