[Elecraft] K2 Transmitter Alignment

[Doug Person]

One thing that I'm finding a problem is I'm running through all the 
voltage checks in the receiver.  They're all really low.  But other than 
the one reference to the BFO possibly being set incorrectly, (its not) 
there is not one hint anywhere as to what the cause might be.  So, I 
have an affect but no causes.  I still have no clue why every voltage in 
both the receiver and transmitter seems extremely low. despite this, the 
receiver seems to receive fine and the only manifestation of the problem 
is low transmitter output.  There most be some common cause to all of 
this.  But so far I have no idea what it is.

Doug -- K0DXV

Don Wilhelm wrote:
> Doug,
>
> Yes, your values are significantly lower than what is expected.
> The first value - Tx Mixer output (U10 pin 4) says that something is wrong
> with either the mixer itself or its inputs.
>
> Go back a bit and do the VCO checks and BFO checks indicated in the lower
> part of Receiver Signal Tracing on page 10 of Appendix E. Continue through
> the BFO checks shown on page 11.  Also check the RF voltage at U10 pin 1
> after measuring the BFO RF Voltage at TP2 (and before exiting from the CAL
> FIL menu). It should be nearly the same as the RF voltage measured at TP2.
> Then check the TX VCO RF voltage at U10 pin 6, it should be in the range of
> 0.3 to 0.4 volts.
>
> If you replaced the 1N34A diode with a good one, all should be well with the
> RF Probe.
>
> 73,
> Don W3FPR
>
>   
>> -----Original Message-----
>>
>> Hi Don and all,
>>
>> As stated in a previous note, my K2 is finished and working but I am not
>> getting full output.  With power set to max I get 9 to 10 watts on 80 to
>> 20,  6 watts on 15 and 3.5 watts on 12 and 10.
>>
>> I went through the "Transmit Mixer, Buffer, Band-Pass Filter, T-R
>> Switch" troubleshooting section on page 14 of Appendix E.  All voltages
>> appear much lower then the indicated "expected" values.  There's not
>> much information about how to interpret these readings.  Also, the 1N34A
>> supplied with the rf probe appears to be defective.  I replaced it with
>> one on hand.  I'm not sure if all 1N34A's are essentially identical and
>> interchangeable or that I might have introduced another variable that is
>> throwing the voltage readings off.  With output power set at 5 watts at
>> 7.000 and 5 watts or better indicated on the output power meter - here's
>> what I have:
>>
>> U10 pin 4: brief value rapidly goes to zero
>> U9 pin 6: .011
>> W6: .004
>> anode D1: .004
>> collector Q5: .032
>> base Q6: .021
>> base Q7: .12
>> base Q8: .142
>> anode D9: .473
>>
>> Thanks for any help,
>>
>> Doug -- KØDXV
>>
>>     
>
>
>
>