Re: K3s transmit bandwidth adjustment?

Posted by Bob McGraw - K4TAX on Feb 10, 2018; 6:57pm
URL: http://elecraft.85.s1.nabble.com/K3s-transmit-bandwidth-adjustment-tp7638068p7638069.html

Based on my measurements the transmit frequency response is limited by
the 2.7 kHz SSB filter.  It is reasonably flat thus +/-3 dB from 400 Hz
to about 2500 Hz.  My next measurement points were 300 Hz {-6 dB} on the
low end and 3000 Hz {-6 dB} on the high end or 2700 Hz.

Thus your numbers of 200 Hz to 2900 Hz is 2.7 kHz, otherwise about the 6
dB points on the filter.  I did not go into the ESSB mode and perform
any measurements.   These were done in DATA mode, thus negating TX EQ
and Speech Processing.  I also did similar measurement with TX ALC OFF
and in USB mode and in USB with TX EQ set to 0 dB at all frequencies and
well below any ALC action.

While I'm always reluctant to measure and report transmit frequency
response of a SSB transmit path, namely because many users not
understanding what takes place, thus would exclaim "that's horrible
frequency response"  while in fact just the opposite is true in that it
makes for darn good sounding audio.

To answer your question, referring to the Elecraft manual and the Fred
Cady book, I find no way to "adjust" the transmit frequency response
other than via the TX EQ.   On that point, I will emphatically state "it
is always better to attenuate a frequency or range of frequencies as
opposed to boost a frequency or range of frequencies".

73

Bob, K4TAX



On 2/10/2018 12:04 PM, Michael Blake wrote:

> Using normal SSB with the stock 2.7kHz. wide crystal filter is there any way to adjust the lower and upper bandwidth frequency ranges other than the TX EQ?
>
> For example how would I adjust so that my 2.7 kHz. bandwidth was from 200Hz. to 2900Hz.?
>
> It is easy to do on the receiver but I cannot figure out how to do this on the transmitter.
>
> 73 - Mike - K9JRI
>
>
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