[Elecraft] Back to the SSB board

[Don Wilhelm]

Ian,

Look at the KSB2 schematic and locate the components at the top of the page
(filter and its switching).

First try CW mode with the filter on the RF Board selected (not OP1).  Then
be certain that everything marked 'RXC' is at 5 to 6 volts (the source is
firmware chip U1 pin 22), and that those points marked 'RXS' are near zero
volts (source is U1 pin 21).  If those two voltages are correct that should
place the proper diodes in either a conducting state or a cutoff state which
will route the signal just like the jumpers in J9 and J10 do (D6 and D10
conducting - also D9 and D13).

When the RXS and RXC signal states are reversed, the signal path is through
the filter on the SSB board - selecting the OP1 filter should activate RXS
and cause RXC to go near zero volts.

T1 and T2 are in the signal path when the OP1 filter is selected, so if you
have trouble only with that filter, look at T1 and T2, but if you have
trouble when the variable filter is selected, look for the problem in the
control voltages or in the switching diodes (and the associated resistors
and chokes).  All diodes should have their cathode ends pointed up away from
the board.

73,
Don W3FPR

> -----Original Message-----
> >
> Thanks for the info Don.  Unfortunately it is not the cause in this
> case.  I have checked the continuity of all the toroids and all seems
> well there.  I also had a response from Stewart G3RXQ and I have looked
> at what he mentioned.
> I don't think it is the VOXDET Stewart as I actually have *some* receive
> with the board plugged in, just well down on where it should be although
> I have looked very carefully for shorts but cannot find any currently.
> A S9 sig on the meter without the board does not move the meter with it
> plugged in and the receive is well down to match.  Any other ideas
> gratefully received.
>
> Skype ID is ian-g0vgs
>
> Ian
>
> --
> Ian J Maude G0VGS
> SysOp GB7MBC DX Cluster
> Member of RSGB, ARRL, GQRP
> K2 #4044
>
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