on air SSB filter alignment

[H. Sawyer-2]

Other hams say my USB sounds tinny, lacking in bass,
on 20 meters, that's the band I'm on these days.

On spectrogram, the received audio curves look great.

What is the process for "on air" adjusting of the
filters for better transmit audio? Is this process
archived somewhere?

Thanks,

Howard

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[Don Wilhelm-3]

Howard,

You said the receive audio curves 'look great' - but are they at the proper
frequencies?

What is the audio frequency shown in Spectrogram at the -3dB points of the
USB passband?  In my experience, the low end should be somewhere near 300
Hz.  Also be certain that this is the passband for the FL1 filter - that is
the only BFO setting used for transmit - you can set FL2 thru FL4 anywhere
you want for receiving.  Also be certain FL1 is set to OP1 and not the
variable filter.

If you have the 2.3 kHz filter bandwidth, set markers (pointers) in
Spectrogram at 300 and 2600 Hz and center the passband between those
markers. (300 and 2300 markers for the older 2.0 kHz filter).

Could it be that you are 'netting' the K2 to a certain frequency rather than
listening to the other signal and tuning for the best audio? - if you are
relying on a particular net frequency shown on the K2 dial, it could simply
be that your dial calibration is off.  See my website www.qsl.net/w3fpr or
the mirror at http://home.earthlink.net/~w3fpr for detail information on
setting the K2 dial calibration.

To adjust 'on the air', you should use a second receiver, being careful not
to overload it, and feed the K2 into a dummy load.  If you can record the
output of the receiver you can better evaluate the voice response.
Determine whether the audio is too high or too low and then use the receive
Spectrogram display to shift the passband a bit up or down as required and
repeat the testing process - continue until satisfied.

73,
Don W3FPR

> -----Original Message-----
>
> Other hams say my USB sounds tinny, lacking in bass,
> on 20 meters, that's the band I'm on these days.
>
> On spectrogram, the received audio curves look great.
>
> What is the process for "on air" adjusting of the
> filters for better transmit audio? Is this process
> archived somewhere?
>
>

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[Ron D'Eau Claire-2]

Howard wrote:

Other hams say my USB sounds tinny, lacking in bass,
on 20 meters, that's the band I'm on these days.

On spectrogram, the received audio curves look great.

What is the process for "on air" adjusting of the
filters for better transmit audio? Is this process
archived somewhere?

-----------------------

Are you looking at FL1 on Spectrogram? FL1 is the ONLY filter/BFO setting
combination used on transmit, regardless of which filter you have selected
for receive.

Still, as the Elecraft SSB module manual says, the final adjustment of your
BFO setting often must be done by listening to your signal. Spectrogram gets
you "in the ball park", but it's not always close enough.

The "stock" K2 SSB filter is intentionally a very narrow filter. It's just
about 2 kHz wide. That's wide enough for excellent intelligibility while
being as narrow as possible for the greatest "punch". The narrower the
bandwidth, the greater the signal-to-noise ratio. But the narrow bandwidth
requires very careful adjustment of the BFO frequency, and it should be
checked with the mic you are using and, preferably, with your voice.  

"Tinny" suggests that the bandpass is too far from the suppressed carrier,
cutting off too many lows.

One excellent way to check your signal is to transmit into a dummy load
while monitoring your signal on an auxiliary receiver. You'll want to record
your voice since it's impossible to hear what you really sound like on the
air while talking. There's too much bone conduction in your head that fills
in spectrum that many not be coming through the rig for your to be able to
tell accurately what other operators hear.

If you don't have a suitable receiver, perhaps a buddy will do some checks
for you on the air. In that case you can plug in your test probe into the
BFO Test point, get on the air and hook up with your buddy, then try making
small adjustments in the BFO frequency for FL1 while he listens to the
difference. You'll have to switch to CAL FIL, chose the filter, make a small
adjustment in the BFO frequency, then switch out to make the new BFO value
get read into memory. Keep a note of where you started and work in small
increments while your buddy reports on how the sound changes.

If your buddy's ears are good, his tuning precise and the filters in his rig
aren't drastically altering your signal, you can make your final adjustments
that way.

Be sure to check and adjust both Upper and Lower sidebands. You can do both
sidebands on any band.

Ron AC7AC


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[Nigel A. Gunn G8IFF/KC8NHF]

Listen to yourself transmitting into a dummy load on another decent
receiver with headphones and adjust your carrier insertion oscillator
 or filter (whichever you do on an Ele) for best audio.

Ron D'Eau Claire wrote:

>Howard wrote:
>
>Other hams say my USB sounds tinny, lacking in bass,
>on 20 meters, that's the band I'm on these days.
>
>On spectrogram, the received audio curves look great.
>
>What is the process for "on air" adjusting of the
>filters for better transmit audio? Is this process
>archived somewhere?
>
>  
>

<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
Nigel A. Gunn. 59 Beadlemead, Milton Keynes, MK6 4HF, England.
Tel [phone]
e-mail [hidden email] or  [hidden email]
www    http://www.ngunn.net  or  http://www.ngunn.demon.co.uk
Amateur radio stations  G8IFF, KC8NHF
Member of  AMSAT-UK #182, ARRL, GQRP Club, QRPARCI, SOC #548  RAYNET
           Flying Pig #385, Dayton ARA #2128, AMSAT-NA  LM-1691,
<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>


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