Re: [K3] CW transmit filter bandwith

[Graham Smith-2]

Many thanks for the on and off-list replies.

It would be useful if folk could write to W8JI and ask him to consider
updating his article (his email is on QRZ.COM) to cover modern CW generation
techniques, since it could result in folk like myself making bad decisions
about choosing transmit filter bandwidths.  I would do this but I think it
needs people with a better understanding of the subject than I have
(although it's improving, thanks!).

Perhaps also the K3 firmware shouldn't allow selection of very narrow
filters for CW transmission?

73 de Graham G3ZOD FISTS #8385
http://www.fists.co.uk


-----Original Message-----

> Tom W8JI was dealing with analog transceivers when that was written.
> The K3 generates the signal digitally in the DSP portion of the
> transceiver, so many of those old "rules of thumb" for analog radios do
> not apply to the K3.  As Guy has said many times on this reflector,
> "This is not your grandaddy's analog radio".
>
> A properly operating K3 does not have key clicks and its transmit IMD is
> very good.
>
> 73,
> Don W3FPR

On 1/17/2011 1:09 PM, Graham Smith wrote:
>> I was reading W8JI's article http://www.w8ji.com/what_causes_clicks.htm
but
>> see that the advice in it (use a narrower filter than an SSB filter for
>> transmitting CW) conflicts with the K3 manual, which says:
>> "Rotate VFO A to select a CW transmit filter (2.7 or 2.8 kHz). Note: Key
>> clicks may result if a narrower filter is selected for CW transmit."
>> Of course I will take the K3 manual's advice, but I am wondering why a
>> narrow filter can cause key clicks?
>>
>> 73 de Graham G3ZOD FISTS #8385
>> http://www.fists.co.uk

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[Don Wilhelm-4]

  Graham,

Tom's comments apply only to certain transceivers.  Many use no filters
in the transmit path.
Specifically, the KX1, K1, and K2 do not run the TX signal through any
filter.  My old HW-101 however does.  So it all depends. The keying
waveshape is controlled in the K2 to minimize keyclicks.

While a narrow filter can reduce keyclicks, that is not applicable to
all transceivers.

Different subject:
The K3 firmware does not allow the selection of any filter other than
the 2.7 (2.8) kHz filter for CW transmit.  The menu does not prohibit
setting it to any filter, it will not transmit and will present you with
a TXF error.

73,
Don W3FPR

On 2/8/2011 4:49 AM, Graham Smith wrote:

> Many thanks for the on and off-list replies.
>
> It would be useful if folk could write to W8JI and ask him to consider
> updating his article (his email is on QRZ.COM) to cover modern CW generation
> techniques, since it could result in folk like myself making bad decisions
> about choosing transmit filter bandwidths.  I would do this but I think it
> needs people with a better understanding of the subject than I have
> (although it's improving, thanks!).
>
> Perhaps also the K3 firmware shouldn't allow selection of very narrow
> filters for CW transmission?
>
> 73 de Graham G3ZOD FISTS #8385
> http://www.fists.co.uk
>
>
> -----Original Message-----
>
>> Tom W8JI was dealing with analog transceivers when that was written.
>> The K3 generates the signal digitally in the DSP portion of the
>> transceiver, so many of those old "rules of thumb" for analog radios do
>> not apply to the K3.  As Guy has said many times on this reflector,
>> "This is not your grandaddy's analog radio".
>>
>> A properly operating K3 does not have key clicks and its transmit IMD is
>> very good.
>>
>> 73,
>> Don W3FPR
> On 1/17/2011 1:09 PM, Graham Smith wrote:
>>> I was reading W8JI's article http://www.w8ji.com/what_causes_clicks.htm
> but
>>> see that the advice in it (use a narrower filter than an SSB filter for
>>> transmitting CW) conflicts with the K3 manual, which says:
>>> "Rotate VFO A to select a CW transmit filter (2.7 or 2.8 kHz). Note: Key
>>> clicks may result if a narrower filter is selected for CW transmit."
>>> Of course I will take the K3 manual's advice, but I am wondering why a
>>> narrow filter can cause key clicks?
>>>
>>> 73 de Graham G3ZOD FISTS #8385
>>> http://www.fists.co.uk
> ______________________________________________________________
> 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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