Mike,
That value for CAL S LO is way off. And that indicates that something
is not connected properly. Look at the schematic for the Control Board
in the lower left corner and check the values and soldering for all the
components around U2 and Q12. You also could have a problem with the
connections (including the connectors) between the Control Board and the
Front Panel RF Gain control.
I measured the voltages on a good working K2 - note that the AGC
Threshold (U2 pin 5) was set to 3.74 volts instead of 3.8 volts which
will make a little difference, but not a whole lot - the voltages should
be proportional (or set your U2 pin 5 voltage to 3.74 before measuring).
With the RF Gain control set to full clockwise:
U2 pin 5 -- 3.74 volts
U2 pin 6 -- 3.74
U2 pin 7 -- 3.73
U2 pin 8 -- 8.34 (this voltage will depend on the output of the 8 volt
regulator)
U2 pin 1 -- 3.74
U2 pin 2 -- 3.44
U2 pin 3 -- 3.42
U2 pin 4 -- 0.00
Q12 base -- 3.68
Emitter ----- 3.42
Collector -- 8.22
Then with the RF Gain set to full Counterclockwise:
U2 pin 5 -- 4.77 volts
U2 pin 6 -- 4.77
U2 pin 7 -- 4.76
U2 pin 8 -- 8.34 (this voltage will depend on the output of the 8 volt
regulator)
U2 pin 1 -- 4.30
U2 pin 2 -- 4.30
U2 pin 3 -- 4.30
U2 pin 4 -- 0.00
Q12 base -- 4.58
Emitter ----- 4.29
Collector -- 8.22
If you find the voltages for U2 pins 5, 6, and 7 do not track my
readings between full clockwise and full CCW, you can suspect a problem
in the connection between the Control board RP6 resistors and the front
panel RF Gain control.
OTOH, if the voltages for pins 5, 6, and 7 do track somewhat similar to
mine, then the RF Gain is OK and the problem is with the components
feeding U2A (pins 1, 2, and 3).
73,
Don W3FPR
On 5/30/2013 7:30 PM, VE3WDM wrote:
Good evening Don, I checked the solder connections on Q12 and U2 all were
good and I even reheated each connection allowing it to flow. I also checked
for proper orientation for U2 and that's ok as well.
D1 is good with band facing toward Q12 and to me that is the proper
direction.
As for CAL S LO the value at which the first bar goes out is 255 and comes
back on at 000
As for CAL S HI I am not able to get any of the bars on the meter to light
up so I do not have a value for you.
Thank very again for your time.
Mike
VE3WDM
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