TX Bandwidth

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TX Bandwidth

David Ahrendts
Quick question: TX ESSB bandwidth is 4.0 kHz. Is AM bandwidth 6.0 kHz?

David A., KK6DA



David Ahrendts   [hidden email]  




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Re: TX Bandwidth

Don Wilhelm
David,

This is an often asked question - but it confuses the IF (or RF)
bandwidth with the audio bandwidth.  You can only get 3 kHz of audio
from a 6 kHz wide AM signal.  If you are using the 13kHz roofing filter
for AM, you might get a bit more audio bandwidth.
It has been that way since the invention of AM modulation.  The audio is
only 1/2 of the transmitted bandwidth.

An AM signal occupying 6 kHz of RF (IF) bandwidth will have audio only
up to 3 kHz.  The AM signal transmits both sidebands, each containing
the same audio information, so you can only recover half of that in the
audio range.

The K3(S), KX3 and the KX2 report the audio bandwidth, not the IF (or
RF) bandwidth.

73,
Don W3FPR

On 8/29/2016 5:13 PM, David Ahrendts wrote:
> Quick question: TX ESSB bandwidth is 4.0 kHz. Is AM bandwidth 6.0 kHz?
>
>

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Re: TX Bandwidth

Grant Youngman-2
This is all true.  Elecraft CAN in fact give you a much better bandwidth (maybe 4 Khz+  AUDIO Tx bandwidth when transmitting through the 13 KHz filter), which is quite good and sounds great on the air according to reports.  So far, they have not been inclined to make it a part of the “standard” feature set and officially ignore virtually all related comments and requests (no matter how many times you genuflect)   It’s really REALLY hard to understand why … they’ll give one interest segment everything they want, and simply ignore this one.  I know .. we’re small in number, and some well known list members like to jump in bash any request for “wider” bandwidth for anything.

I guess “timepiece" accuracy just gets more swipes.  Like I don’t already have a watch :(

At this point in THAT thread, I’m actually surprised there haven’t been complaints that they don’t offer interchangeable watch bands for the KX2  …

Grant NQ5T


> On Aug 29, 2016, at 5:27 PM, Don Wilhelm <[hidden email]> wrote:
>
> David,
>
> This is an often asked question - but it confuses the IF (or RF) bandwidth with the audio bandwidth.  You can only get 3 kHz of audio from a 6 kHz wide AM signal.  If you are using the 13kHz roofing filter for AM, you might get a bit more audio bandwidth.
> It has been that way since the invention of AM modulation.  The audio is only 1/2 of the transmitted bandwidth.
>
> An AM signal occupying 6 kHz of RF (IF) bandwidth will have audio only up to 3 kHz.  The AM signal transmits both sidebands, each containing the same audio information, so you can only recover half of that in the audio range.
>
> The K3(S), KX3 and the KX2 report the audio bandwidth, not the IF (or RF) bandwidth.
>

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Re: TX Bandwidth

Joe Subich, W4TV-4

On 8/29/2016 7:26 PM, GRANT YOUNGMAN wrote:
> This is all true. Elecraft CAN in fact give you a much better
> bandwidth (maybe 4 Khz+ AUDIO Tx bandwidth when transmitting through
> the 13 KHz filter)

The K3 can *already do* 4 KHz ESSB with either the 6 KHz or 13 KHz IF
filter.  Why is that not enough considering that there is practically
no energy in the human voice above 3 KHz - certainly not enough to
override the background "band noise" on most HF bands?

73,

   ... Joe, W4TV


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Re: TX Bandwidth

Grant Youngman-2
My comment was related to  TX bandwidth in AM, which was the point of Dos responst, not t ESSB.  My mistake … sometimes the brain does what you don’t want it to do.

For the record …


Grant NQ5T


> On Aug 29, 2016, at 7:57 PM, Joe Subich, W4TV <[hidden email]> wrote:
>
>
> On 8/29/2016 7:26 PM, GRANT YOUNGMAN wrote:
>> This is all true. Elecraft CAN in fact give you a much better
>> bandwidth (maybe 4 Khz+ AUDIO Tx bandwidth when transmitting through
>> the 13 KHz filter)
>
> The K3 can *already do* 4 KHz ESSB with either the 6 KHz or 13 KHz IF
> filter.  Why is that not enough considering that there is practically
> no energy in the human voice above 3 KHz - certainly not enough to
> override the background "band noise" on most HF bands?
>
> 73,
>
>  ... Joe, W4TV
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Re: TX Bandwidth

Grant Youngman-2
Apparently, I can’t type either … well, at least I can write in cursive with a fine degree of penmanship,  which is more than I can say for my grandchildren :-)


> On Aug 29, 2016, at 8:03 PM, GRANT YOUNGMAN <[hidden email]> wrote:
>
> My comment was related to  TX bandwidth in AM, which was the point of Dos responst, not t ESSB.  My mistake … sometimes the brain does what you don’t want it to do.
>
> For the record …
>
>
> Grant NQ5T
>
>

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Re: TX Bandwidth

Phil Wheeler-2
Until I started typing on a computer in 1983
(Radio Shack Model 100) I had great handwriting.  
Now just great handwringing :-)

Phil W7OX

On 8/29/16 5:08 PM, GRANT YOUNGMAN wrote:

> Apparently, I can’t type either … well, at least I can write in cursive with a fine degree of penmanship,  which is more than I can say for my grandchildren :-)
>
>
>> On Aug 29, 2016, at 8:03 PM, GRANT YOUNGMAN <[hidden email]> wrote:
>>
>> My comment was related to  TX bandwidth in AM, which was the point of Dos responst, not t ESSB.  My mistake … sometimes the brain does what you don’t want it to do.
>>
>> For the record …
>>
>>
>> Grant NQ5T

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