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K2 SSB

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Raimon-3

K2 SSB

Hi all

I am having troubles with my K2, and need your help.

My K2 is nr. 3529, with K2/100, KAT 100 and KSB2SSB

It has been working fine until now, mainly CW and BPSK31

Now it continues to work all right in CW in all bands, but in SSB power
output drops substantiably in 20, 30, 15 ,12 and 10 meters bands.

As an example, readings of output power in 14070 are:

CW 80 w

SSB L 50 w

SSB U 20 w

SSB r inv. 20 w

Readings made with K2 connected to a dummy load trhough a Kenwood AT230,
power setting in K2 100 w., injecting a 1000 Hz tune signal from
MultiPSK programm. (same problem with a microphone)

No problems in bands 80, 40 and 30 (80 w. Readings in all modes)

In lower bands all leds in the K2 light when transmitting, in the other
bands just 1 to 3 leds light.

I suspect the KSB2SSB module. Where should I look for the cause of this
problem?

Many thanks in advance

Raimon

EA3EZO

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Don Wilhelm-4

Re: K2 SSB

Raimon,

I do believe your first checks should be on the KSB2 option board.
Look at the schematic for the KSB2 in the lower left corner area - you
will find several passive components associated with Q1, D1 and D2 -
those are the components are in the SSB ALC section and are the ones to
check.

I would look first for a poor solder connection. It is not uncommon for
a marginal solder connection to fail after a few years even if it worked
fine initially - once an oxide coating develops, it will fail (usually
because of a higher than normal resistance at the connection). It
*could* be a component failure, but I would check the soldering first
and re-flow it if there is any question at all about its current quality.

I tend to believe that the band dependency is a 'red herring' and is the
simple result of the fact that the intrinsic transmit chain gain of the
K2/100 goes down as the frequency is increased.

If you find no problem obvious on the KSB2 board, I would suggest that
you remove the KPA100 and test the base K2 for a similar condition.

73,
Don W3FPR

raimon wrote:

> Hi all
>
> I am having troubles with my K2, and need your help.
>
> My K2 is nr. 3529, with K2/100, KAT 100 and KSB2SSB
>
> It has been working fine until now, mainly CW and BPSK31
>
> Now it continues to work all right in CW in all bands, but in SSB
> power output drops substantiably in 20, 30, 15 ,12 and 10 meters bands.
>
> As an example, readings of output power in 14070 are:
>
> CW 80 w
>
> SSB L 50 w
>
> SSB U 20 w
>
> SSB r inv. 20 w
>
> Readings made with K2 connected to a dummy load trhough a Kenwood
> AT230, power setting in K2 100 w., injecting a 1000 Hz tune signal
> from MultiPSK programm. (same problem with a microphone)
>
> No problems in bands 80, 40 and 30 (80 w. Readings in all modes)
>
> In lower bands all leds in the K2 light when transmitting, in the
> other bands just 1 to 3 leds light.
>
> I suspect the KSB2SSB module. Where should I look for the cause of
> this problem?
>
> Many thanks in advance
>
> Raimon
>
> EA3EZO
>
> [hidden email] <mailto:[hidden email]>
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
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>

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Raimon-3

K2 SSB

Dear Don
I thank you for the information.
Following your advice. I looked first for a bad solder in the KSB2
module. As no poor solder was apparent, I decided to resolder all
connections. After this re-work the failure has been cured. The K27100
in SSB mode is working again as it had been until recently.
I thought that my soldering skills were good enough, but I was wrong. Hi.
Many thanks for your help ¡¡¡
Best regards, 73
EA3EZO Raimon

En/na Don Wilhelm ha escrit:

> Raimon,
>
> I do believe your first checks should be on the KSB2 option board.
> Look at the schematic for the KSB2 in the lower left corner area - you
> will find several passive components associated with Q1, D1 and D2 -
> those are the components are in the SSB ALC section and are the ones
> to check.
>
> I would look first for a poor solder connection. It is not uncommon
> for a marginal solder connection to fail after a few years even if it
> worked fine initially - once an oxide coating develops, it will fail
> (usually because of a higher than normal resistance at the
> connection). It *could* be a component failure, but I would check the
> soldering first and re-flow it if there is any question at all about
> its current quality.
>
> I tend to believe that the band dependency is a 'red herring' and is
> the simple result of the fact that the intrinsic transmit chain gain
> of the K2/100 goes down as the frequency is increased.
>
> If you find no problem obvious on the KSB2 board, I would suggest that
> you remove the KPA100 and test the base K2 for a similar condition.
>
> 73,
> Don W3FPR
>
> raimon wrote:
>> Hi all
>>
>> I am having troubles with my K2, and need your help
> .................................................
>> Now it continues to work all right in CW in all bands, but in SSB
>> power output drops substantiably in 20, 30, 15 ,12 and 10 meters bands.
>>
>>
>> I suspect the KSB2SSB module. Where should I look for the cause of
>> this problem?
>>
>> Many thanks in advance
>>
>> Raimon
>>
>> EA3EZO
>>
>> [hidden email] <mailto:[hidden email]>
>>
>> _______________________________________________
>

Don Wilhelm-4

Re: K2 SSB

Raimon,

I am pleased to hear you now have it working.
Yes, solder connections may be like that, particularly if the solder pad
did not receive enough heat during the initial soldering. No matter how
good one's soldering skills are, it is always possible to be distracted
and not to notice the point when the solder flows out onto the pad
telling you that it is a good and complete connection.

73,
Don W3FPR

raimon wrote:

> Dear Don
> I thank you for the information.
> Following your advice. I looked first for a bad solder in the KSB2
> module. As no poor solder was apparent, I decided to resolder all
> connections. After this re-work the failure has been cured. The K27100
> in SSB mode is working again as it had been until recently.
> I thought that my soldering skills were good enough, but I was wrong. Hi.
> Many thanks for your help ¡¡¡
> Best regards, 73
> EA3EZO Raimon