Don,
Driver Output RF last measured at 2.3V rms (earlier it was 3.6)
which I think is normal.
PA Input RF(Q7) was .55 and (Q8) was .55 which I think is also normal.
John
AB8WH
On May 30, 2006, at 12:15 AM, Don Wilhelm wrote:
John,
The PA Transistor Test values will vary depending on your
particular DMM -
some will show forward voltage while others will show ohms. Your .55
reading on the base to emitter with the probes either way would
indicate
something to be concerned about - but since you are testing in-
circuit, the
problem could be something other than the output transistors (we
can get to
that later if need be).
When doing the transmit measurements (DC Voltages or others), it is
always a
good idea to connect a 50 ohm dummy load. Make your measurements
during
quick key-down (or TUNE) periods, and give things a chance to cool
down
after each measurement.
Your RF voltage measurements look OK for a K2 that is not developing
sufficient power output - the 'too high' readings are to be
expected under
such conditions. What is the Driver Output RF Voltage and the PA
Input RF
Voltage? These measurements will tell if the problem is the driver
or the
finals. If the Driver Output is low, the first thing to check is the
emitter resistor for Q6.
73,
Don W3FPR
-----Original Message-----
Now, Here are the aberrant values:
Band-Pass Filter Output: 0.12 (Expected is .03)
T-R Switch #1 Output: .141 (Expected is .029)
Driver Input: 0.16 (Expected .026)
RF Detector Input: 0.7 (Expected is 2.0)
Q7 and Q8: both have been replaced once already
Transistor test Pos. Lead on Base: E and C both read about .55
(volts, I guess..."k" is listed in the manual)
Neg. Lead on Base: "OL" on C, .55
on E(expected is 1.3)
That's where I am at the moment.
If someone can explain what the settings should be for DC Voltage
tables during TRANSMIT, I would really appreciate it.
In the manual (p14) It says no antenna...this doesn't sound right for
transmit. What did I miss? Then, I can tackle the DC readings.
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