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[K2] Question about tuning K2 for SSB..

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VK7JB

[K2] Question about tuning K2 for SSB..

Hi All,

I'm learning to drive my new K2/100 and have reached a conceptual block that will betray a fundamental lack of understanding, but here goes anyway...

My K2 dial frequency reads about 20hz under the actual frequency - receiving WWV on 10000.00, the LCD frequency readout reads 9999.98. That's all good. But, when I'm working SSB and want to make contact with a station already transmitting on a particular frequency, how do I handle the tuning to ensure I'm transmitting on his frequency exactly. Do I tune my K2 to achieve best resolved audio receiving his signal, regardless of the actual frequency displayed on my LCD, then assume when I hit TX I'll be transmitting exactly on his frequency? Or is there any other way to account for this small 20hz shift, to make sure I'm transmitting exactly where he is tuned?

I'm running my K2 with the MH-2 mic and last night got reports of "muffled" audio. I suspect I'll need to tweak the SSB filter passband position- the position looks good on Spectrogram with the low frequency roll off for the SSB Tx filter sitting around 300hz, but I understand it may need some "optimising" with live audio monitoring. I did wonder if my tuning technique was contributing to the problem - perhaps I'm not transmitting exactly where they're listening.

I hope that makes sense. Any advice always gratefully received,

73,
John
VK7JB

Don Wilhelm-4

Re: [K2] Question about tuning K2 for SSB..

John,

A 20 Hz mis-tuning of a SSB signal usually will not be noticed, 50 Hz
maybe, and 100 Hz definitely.

So yes, you would normally tune the station until it 'sounds right' and
then transmit. That assumes that you are using the same filter for
transmit and receive.

You can make some trials with tests made with another ham who knows how
you should sound.
Move the filter passband up or down in 25 Hz increments to see if you
have achieved a more suitable position for your voice.

73,
Don W3FPR

On 11/3/2010 10:20 PM, VK7JB wrote:

> Hi All,
>
> I'm learning to drive my new K2/100 and have reached a conceptual block that
> will betray a fundamental lack of understanding, but here goes anyway...
>
> My K2 dial frequency reads about 20hz under the actual frequency - receiving
> WWV on 10000.00, the LCD frequency readout reads 9999.98. That's all good.
> But, when I'm working SSB and want to make contact with a station already
> transmitting on a particular frequency, how do I handle the tuning to ensure
> I'm transmitting on his frequency exactly. Do I tune my K2 to achieve best
> resolved audio receiving his signal, regardless of the actual frequency
> displayed on my LCD, then assume when I hit TX I'll be transmitting exactly
> on his frequency? Or is there any other way to account for this small 20hz
> shift, to make sure I'm transmitting exactly where he is tuned?
>
> I'm running my K2 with the MH-2 mic and last night got reports of "muffled"
> audio. I suspect I'll need to tweak the SSB filter passband position- the
> position looks good on Spectrogram with the low frequency roll off for the
> SSB Tx filter sitting around 300hz, but I understand it may need some
> "optimising" with live audio monitoring. I did wonder if my tuning
> technique was contributing to the problem - perhaps I'm not transmitting
> exactly where they're listening.
>
> I hope that makes sense. Any advice always gratefully received,
>
> 73,
> John
> VK7JB

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w2bvh

Re: [K2] Question about tuning K2 for SSB..

In reply to this post by VK7JB

You can adjust the ssb filter by listening to your own voice on the
rig and adjusting the ssb filter to what sounds best to you. To monitor
your own voice set the SSBA option to "BAL". Then got to CAL FIL for the
filter you want to adjust and adjust it (a little at a time) while
talking into the mic. The only caveat is that your mic has to be hot
(making a signal) when the PTT line is *not* active. If your mic opens
the mic signal line when PTT is not pressed you will have to temporarily
jump out the switch contact that opens that signal. I found it was
better if someone else was listening to my voice on the headphones
instead of myself. They'll let you know when you have adjusted the ssb
filter for the best audio.

Don't forget to reset the SSBA "BAL" option back to its previous value
after you're done.

Sounds harder than it is. You can probably do the whole thing in 1/2 hour.

GL & 73,
Lenny W2BVH

On 11/3/2010 10:20 PM, VK7JB wrote:

VK7JB

[K2] Aligning my K2/100 - things I learnt...

In reply to this post by VK7JB

Thanks to everyone for your tips. I had a lot of helpful advice, on and off the reflector, and all is sorted out and understood now.

FWIW, I re-calibrated the 4MHz reference oscillator using the N6KR method and my frequency display is now only 10hz off WWV. I'm very happy with that. This is about the 3rd or 4th pass using this method. On the final pass, I noticed 2 things about my K2 and taking them into account helped reduce the error: firstly, the spot tone of my K2, set for 600hz, is actually 610hz, not 600hz. Secondly, when entering CAL FCTR mode after zero beating WWV on sideband, the beat tone drops 10hz. I found reference to this in another posting, but somehow missed it the first few times around. It's easy to account for once you notice it. There is some drift (+/-40hz or so) as the K2/100 heats up after long overs @100W, but that is easily compensated for while I'm operating, now that I know how (thanks Tom!).

The sideband filters are now well tuned and the audio reports are good - no longer "muffled". Adjusting OP1 was easy in the end. I found that very small changes in frequency, just 25-50hz, make a big difference to the sound of the transmitted audio. I had to listen carefully and experiment to get the audio profile I wanted. Adjusting the OP1 SSB filter for optimum transmit audio made the received audio a little "sharp" for my taste, so I did as has been suggested elsewhere and set FL2 to OP1 and adjusted the audio passband of that filter to accentuate the lows and reduce some of the highs. I keep FL2 in on receive and now I have great audio on both RX and TX.

Thanks again for everyones' input. I would never have completed this project without the support and collective know-how of this group. The K2/100 is sitting on my dest here, but I still can't really believe I've done it.

73,

John
VK7JB