[Elecraft] K2 SSB

[Don Wilhelm]

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
>
> rfuidio at telefonica.net <mailto:rfuidio at telefonica.net>
>
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