[Amps] Alpha 78 Control Circuit 'Issue'

[Paul Gerhardt]

Thinking about the control voltage 20V or so being present at the relay jack
even in Standby lead me to discover that the QSK board CB-3 has been
modified.  The trace to the Aux/Key jack has been cut and the relay jack is
'strapped' to the control circuit ALL the time.  Anybody know the reason or
logic to this?  This means that the exciter keying relay is 'disconnected'.
Before I start to wire it back to 'stock' is there anything else to consider
or changes that are recommended on CB-3?




On Thu, Jan 21, 2010 at 8:24 PM, Paul Gerhardt <phgerhardt at gmail.com> wrote:

> Any Alpha 78 techs?
>
> Am having trouble with the control circuitry.
>
> TR switching works if in standby.  (it is putting out power in 'standby')
>
> When CW OR SSB buttons are down the 78 stays in Transmit.
>
> 60 sec timers is working
> HV is working and switching from Hi to Low
> RF power output is good
> Meters all seem good
>
> Shorting Relay Jack in standby (both CW AND SSB buttons 'out') causes T/R
> switching and RF Sensing (to inhibit T/R switching with input) works
> in 'Standby' .
>
> When CW OR SSB button is down T/R switching is 'locked' in Transmit Relay
> Jack (open or shorted) makes no difference.
>
>
>
>
> --
> Paul Gerhardt
> K3PG
> http://pgerhardt.blogspot.com
>
>