[Elecraft] K2 troubleshooting

[John Wiener]

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.
>>
>