K2/10 (S/N 7967) - SSB voice on transmit issue

[Elecraft mailing list]

Hello Elecraft Community,

I have recently built the K2/10 and have enjoyed listening to the receiver.  I have more recently added the KSB2 SSB adapter and have noticed my voice is either very high-pitched or low-pitched on an external receiver while using a 50-ohm dummy load.  

After spending some time on the issue of SSB voice on transmit, I realized that if I mistune the K2 on transmit that my voice would appear to sound normal with no humming on an external receiver.  The following are examples:

10m  28529.45u from K2 to external receiver set at 28530.00 (-550 Hz on K2 side)
12m  24939.19u from K2 to external receiver set at 24940.00 (-810 Hz on K2 side)
15m  21229.30u from K2 to external receiver set at 21230.00 (-700 Hz on K2 side)
17m  18119.35u from K2 to external receiver set at 18120.00 (-650 Hz on K2 side)
20m  14159.70u from K2 to external receiver set at 14160.00 (-300 Hz on K2 side)
40m    7149.75L from K2 to external receiver set at   7150.00 (-250 Hz on K2 side)
80m.   3750.30L from K2 to external receiver set at   3750.00 (+300Hz on K2 side)

I have previously adjusted C22 using an external frequency counter on TP3 along with the K2’s frequency counter probe to get the readings from both the external frequency and K2’s to match.  And yes, I’ve adjusted the filter and BFO settings per the KSB2 operating instructions.

I would welcome any suggestions to get a resolve to this problem.

73,

John - KF6QPC
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[Don Wilhelm]

John,

It sounds like you need to adjust the BFO settings for the FL1 SSB
filter.  You can do that in receive.
It is best if you do that using a visual aid like an audio spectrum
analyzer to be able to see the position of the filter passband in the
audio spectrum.  Spectrogram is one such analyzer - it runs on your
computer and soundcard.  Non-Windows folks will have to find some other
program.

To see how to set up and use Spectrogram 5.17 download the .pdf at
http://www.mmccs.com/mmarc/n0ss/k2_filters_using_gram_v5r17.pdf.

You can download Spectrogram from my website www.w3fpr.com.  On the home
page, scroll near the bottom to find the links.  Both versions 5.17 and
16 are there.

73,
Don W3FPR

On 11/2/2020 10:45 AM, JOHN CAPEL via Elecraft wrote:
> Hello Elecraft Community,
>
> I have recently built the K2/10 and have enjoyed listening to the receiver.  I have more recently added the KSB2 SSB adapter and have noticed my voice is either very high-pitched or low-pitched on an external receiver while using a 50-ohm dummy load.
>
> After spending some time on the issue of SSB voice on transmit, I realized that if I mistune the K2 on transmit that my voice would appear to sound normal with no humming on an external receiver.  The following are examples:
>
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