Further troubleshooting of my new K2 build reveals that transmit and
receive on the 30-metre band works well. But all other bands, transmit
and receive, don't work.
...
I am trying to think of what's common among all bands except 30 metres,
transmit and receive, where a problem could lie. The fact that 30 metres
works OK confirms that much of the rig is working correctly. Since 30
and 20 metres share a band-pass filter as well as a low pass filter
makes this all the more confusing.
The K2 uses latching relays for band switching (as well as VFO
switching, ext ant switching and some other things).
So, if your K2 can't drive its relays (or no longer can drive its
relays) then many things still work, except band switching.
All of this is driven from U1 on the main board.
U1 has a separate voltage regulator, U2. I am pretty sure that the main
CPU on the control board yells at you if it can't talk to the IO
controller U1 on the main board. But perhaps the voltage is good enough
for the controller to work but not for the relays to operate.
If you change bands, do you hear the relays operate? After you change
bands, after a second or so, you should hear a distinct "cccclickkk" as
several relays are changed.
Also, since you are measuring, can you verify that if you change bands,
the relays switch as expected?
When looking at the 2005 schematics, I see that all relays - even on
optional modules like the 160m module, have a voltage "RY COM" to switch
against (mainboard, sheet 3). The schematic says that if one relay needs
to be operated, all the other relays are pulled in the other direction.
I would make sure that this "RY COM" isn't grounded or something.
73,
Geert Jan PE1HZG
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