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Sherwood receiver test on KX3

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webrehm

Sherwood receiver test on KX3

The Sherwood test of the KX3 says this in the notes for the superscript V
"At 1 kHz performance is opposite sideband rejection limited. On CW consider switching to 8-kHz IF. Note: Roofing filter disabled in this mode."
I do not see anything in the manual about the 8 Khz IF mode.
It is my understanding that when the roofing filter is used, which is a low pass filter, that the IF is 0 Hz.
When the roofing filter is bypassed (FIL1) does this mean that the IF is shifted up to 8 KHz?
What is the IF of the IQ outputs?
Can someone explain this to me because I am confused.

tks

Dennis

mzilmer

Re: Sherwood receiver test on KX3

The 8 KHz IF mode is called DUAL WATCH or DUAL RX. I/Q are "baseband" outputs.

Matt Zilmer
Consultant - Product Management Dept.
Magellan Navigation / MiTAC Digital Corp.
Tel: (909) 394-6052
Cell: (909) 730-6552
Si fractum non sit, noli id reficere

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of webrehm
Sent: Tuesday, August 14, 2012 1:47 PM
To: [hidden email]
Subject: [Elecraft] Sherwood receiver test on KX3

The Sherwood test of the KX3 says this in the notes for the superscript V "At 1 kHz performance is opposite sideband rejection limited. On CW consider switching to 8-kHz IF. Note: Roofing filter disabled in this mode."
I do not see anything in the manual about the 8 Khz IF mode.
It is my understanding that when the roofing filter is used, which is a low pass filter, that the IF is 0 Hz.
When the roofing filter is bypassed (FIL1) does this mean that the IF is shifted up to 8 KHz?
What is the IF of the IQ outputs?
Can someone explain this to me because I am confused.

tks

Dennis

--
View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-receiver-test-on-KX3-tp7561045.html
Sent from the Elecraft mailing list archive at Nabble.com.
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Lyle Johnson

Re: Sherwood receiver test on KX3

Also, see the "RX SHFT" menu entry.

73,

Lyle KK7P

> The 8 KHz IF mode is called DUAL WATCH or DUAL RX.

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Matt Maguire

Re: Sherwood receiver test on KX3

In reply to this post by mzilmer

Hi Matt,

I thought that the "RX SHFT" menu item was what set the IF to 8kHz, not the dual watch (the dual watch may or may not enable an 8kHz shift as well. In a simple implementation of dual watch, the first demodulator would sit on centre frequency, and the second would shift +/- 15kHz from that. In a trickier implementation, VFO would be shifted up or down 8kHz or even more, and VFOB would then be able to range a bit further, and give a bit more than the current +/-15kHz separation).

As for whether the RX SHFT affects the centre frequency of the RX I/Q outputs, I'm not sure. It would not be hard to verify -- just tune in to WWV with RX SHFT on, and see where in the waterfall the signal appears (eg. at centre, or at centre+8kHz)

73, Matt VK2ACL

On 15/08/2012, at 7:23 AM, Matthew Zilmer <[hidden email]> wrote:

> The 8 KHz IF mode is called DUAL WATCH or DUAL RX. I/Q are "baseband" outputs.
>
> Matt Zilmer
> Consultant - Product Management Dept.
> Magellan Navigation / MiTAC Digital Corp.
> Tel: (909) 394-6052
> Cell: (909) 730-6552
> Si fractum non sit, noli id reficere
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On Behalf Of webrehm
> Sent: Tuesday, August 14, 2012 1:47 PM
> To: [hidden email]
> Subject: [Elecraft] Sherwood receiver test on KX3
>
> The Sherwood test of the KX3 says this in the notes for the superscript V "At 1 kHz performance is opposite sideband rejection limited. On CW consider switching to 8-kHz IF. Note: Roofing filter disabled in this mode."
> I do not see anything in the manual about the 8 Khz IF mode.
> It is my understanding that when the roofing filter is used, which is a low pass filter, that the IF is 0 Hz.
> When the roofing filter is bypassed (FIL1) does this mean that the IF is shifted up to 8 KHz?
> What is the IF of the IQ outputs?
> Can someone explain this to me because I am confused.
>
> tks
>
> Dennis
>
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-receiver-test-on-KX3-tp7561045.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> 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
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>
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mzilmer

Re: Sherwood receiver test on KX3

You're correct. I got my mental wires crossed. Shouldn't try to think about fun stuff like radio, while at work....

Matt Zilmer
Consultant - Product Management Dept.
Magellan Navigation / MiTAC Digital Corp.
Tel: (909) 394-6052
Cell: (909) 730-6552
Si fractum non sit, noli id reficere

-----Original Message-----
From: Matt Maguire [mailto:[hidden email]]
Sent: Tuesday, August 14, 2012 2:50 PM
To: Matthew Zilmer
Cc: webrehm; [hidden email]
Subject: Re: [Elecraft] Sherwood receiver test on KX3

Hi Matt,

I thought that the "RX SHFT" menu item was what set the IF to 8kHz, not the dual watch (the dual watch may or may not enable an 8kHz shift as well. In a simple implementation of dual watch, the first demodulator would sit on centre frequency, and the second would shift +/- 15kHz from that. In a trickier implementation, VFO would be shifted up or down 8kHz or even more, and VFOB would then be able to range a bit further, and give a bit more than the current +/-15kHz separation).

As for whether the RX SHFT affects the centre frequency of the RX I/Q outputs, I'm not sure. It would not be hard to verify -- just tune in to WWV with RX SHFT on, and see where in the waterfall the signal appears (eg. at centre, or at centre+8kHz)

73, Matt VK2ACL

On 15/08/2012, at 7:23 AM, Matthew Zilmer <[hidden email]> wrote:

> The 8 KHz IF mode is called DUAL WATCH or DUAL RX. I/Q are "baseband" outputs.
>
> Matt Zilmer
> Consultant - Product Management Dept.
> Magellan Navigation / MiTAC Digital Corp.
> Tel: (909) 394-6052
> Cell: (909) 730-6552
> Si fractum non sit, noli id reficere
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of webrehm
> Sent: Tuesday, August 14, 2012 1:47 PM
> To: [hidden email]
> Subject: [Elecraft] Sherwood receiver test on KX3
>
> The Sherwood test of the KX3 says this in the notes for the superscript V "At 1 kHz performance is opposite sideband rejection limited. On CW consider switching to 8-kHz IF. Note: Roofing filter disabled in this mode."
> I do not see anything in the manual about the 8 Khz IF mode.
> It is my understanding that when the roofing filter is used, which is a low pass filter, that the IF is 0 Hz.
> When the roofing filter is bypassed (FIL1) does this mean that the IF is shifted up to 8 KHz?
> What is the IF of the IQ outputs?
> Can someone explain this to me because I am confused.
>
> tks
>
> Dennis
>
>
>
>
> --
> View this message in context:
> http://elecraft.365791.n2.nabble.com/Sherwood-receiver-test-on-KX3-tp7
> 561045.html Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> 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
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>
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Don Wilhelm-4

Re: Sherwood receiver test on KX3

In reply to this post by webrehm

Let me try to help a bit.
On the roofing filter/8 kHz shift, you have the cart before the horse.
The 8 kHz shift requires that the roofing filter be bypassed. There are
other cases where the roofing filter may be bypassed without the 8 kHz
shift. For instance Dual Watch being active.

There is no IF associated with the IQ outputs, it is "bassband" which
means it is the same thing as the "0 Hz" that you are referring to.

Actually "baseband" is a better term than "0 Hz" - technically 0 Hz is a
DC signal with no variation. Baseband can and does contain modulation.

73,
Don W3FPR

On 8/14/2012 4:47 PM, webrehm wrote:

> It is my understanding that when the roofing filter is used, which is a low
> pass filter, that the IF is 0 Hz.
> When the roofing filter is bypassed (FIL1) does this mean that the IF is
> shifted up to 8 KHz?
> What is the IF of the IQ outputs?
> Can someone explain this to me because I am confused.
>
> tks
>
> Dennis
>
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-receiver-test-on-KX3-tp7561045.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> 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
>

Matt Maguire

Re: Sherwood receiver test on KX3

Thanks Don. I was distracted by Matt Z's comments, and forgot to treat the original question :-)

73, Matt VK2ACL

On 15/08/2012, at 8:12 AM, Don Wilhelm <[hidden email]> wrote:

> Let me try to help a bit.
> On the roofing filter/8 kHz shift, you have the cart before the horse.
> The 8 kHz shift requires that the roofing filter be bypassed. There are
> other cases where the roofing filter may be bypassed without the 8 kHz
> shift. For instance Dual Watch being active.
>
> There is no IF associated with the IQ outputs, it is "bassband" which
> means it is the same thing as the "0 Hz" that you are referring to.
>
> Actually "baseband" is a better term than "0 Hz" - technically 0 Hz is a
> DC signal with no variation. Baseband can and does contain modulation.
>
> 73,
> Don W3FPR
>
> On 8/14/2012 4:47 PM, webrehm wrote:
>> It is my understanding that when the roofing filter is used, which is a low
>> pass filter, that the IF is 0 Hz.
>> When the roofing filter is bypassed (FIL1) does this mean that the IF is
>> shifted up to 8 KHz?
>> What is the IF of the IQ outputs?
>> Can someone explain this to me because I am confused.
>>
>> tks
>>
>> Dennis
>>
>>
>>
>>
>> --
>> View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-receiver-test-on-KX3-tp7561045.html
>> Sent from the Elecraft mailing list archive at Nabble.com.
>> ______________________________________________________________
>> 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]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

webrehm

Re: Sherwood receiver test on KX3

So if you are running an panadapter and turn on RX shift then what happens to the panadapter display? Are the frequencies shifted on the display by 8 KHz? The Sherwood data would indicate to me that using the 8 KHz shift is a good thing to do all the time if you do not have the roofing filter and since the 2 Khz dynamic range is 96 dB without the roofing filter and with 8 KHz shift on, you get great performance this way.

tks
Dennis

Rich Heineck

Re: Sherwood receiver test on KX3

In reply to this post by webrehm

If operating CW, another approach that could be used to avoid a strong signal in the
opposite sideband is to hold the MODE button to go into CW REV.

Rich AC7MA

On 8/14/2012 1:47 PM, webrehm wrote:

> The Sherwood test of the KX3 says this in the notes for the superscript V
> "At 1 kHz performance is opposite sideband rejection limited. On CW consider
> switching to 8-kHz IF. Note: Roofing filter disabled in this mode."
> I do not see anything in the manual about the 8 Khz IF mode.
> It is my understanding that when the roofing filter is used, which is a low
> pass filter, that the IF is 0 Hz.
> When the roofing filter is bypassed (FIL1) does this mean that the IF is
> shifted up to 8 KHz?
> What is the IF of the IQ outputs?
> Can someone explain this to me because I am confused.
>
> tks
>
> Dennis
>
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-receiver-test-on-KX3-tp7561045.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> 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
>

Matt Maguire

Re: Sherwood receiver test on KX3

In reply to this post by webrehm

Yes, if you are running a panadapter fed from the KX3 RX I/Q output, and you enable 8kHz shift, then all the signals are shifted up on the panadapter display by 8kHz.

Further, if you enable dual watch, then the main signal from VFO A remains at centre frequency, and VFO B is plus or minus 15 kHz from centre. If you have RX SHFT enabled, then you can't enable Dual Watch.

As I hinted earlier, a possible future enhancement may be to combine RX SHFT and dual watch to extend the range of the dual watch. In this case, if VFO B was below VFO A, you would use a positive offset for VFO A, whereas if VFO B is above VFO A, then you would use a negative offset for VFO A. It's a bit of mucking around, so you it is arguable whether the benefit of the extended range really justfies the effort.

73, Matt VK2ACL.

On 15/08/2012, at 11:16 AM, webrehm <[hidden email]> wrote:

> So if you are running an panadapter and turn on RX shift then what happens to
> the panadapter display? Are the frequencies shifted on the display by 8 KHz?
> The Sherwood data would indicate to me that using the 8 KHz shift is a good
> thing to do all the time if you do not have the roofing filter and since the
> 2 Khz dynamic range is 96 dB without the roofing filter and with 8 KHz shift
> on, you get great performance this way.
>
> tks
> Dennis
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-receiver-test-on-KX3-tp7561045p7561058.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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> Please help support this email list: http://www.qsl.net/donate.html

webrehm

Re: Sherwood receiver test on KX3

It appears that the kx3 does not have dynamic image rejection, rather a one time calibration for image rejection. Has there been any talk of the KX3 implementing dynamic image rejection? Perhaps a future SW revision where the image rejection goes to > 90 dB. The Flex products implemented dynamic image rejection in 2009 and it is a well documented process in technical journals.

tks

Dennis

Ignacy

Re: Sherwood receiver test on KX3

Don't forget that KX3 is QRP radio for portable operation. I tried hard to hear an image in KX3, and could not.
Ignacy