[Elecraft] [K2] No Transmit Power

[Brian Denley]

?I am just about at the end of my rope trying to get this K2 to transmit. 
Nothing is coming out of the transmitter because nothing seems to be going 
into the PA circuit.  The receiver circuits all work fine.  All RF board 
transistors and diodes check out fine as far as DC is concerned but my RF 
probe does not function and I am unable to find the fault.  I suspect the 
T/R switch or whatever circuit generates the RF signal in the first place 
but the trouble shooting help in the manual does not go yery deep on those 
issues.  What is my next step?  Does Elecraft offer a repair service?  I 
have been at this for 4 weeks now with no progress at all.
Thanks
Brian Denley
http://home.comcast.net/~b.denley/index.html


----- Original Message ----- 
From: "Don Wilhelm" <w3fpr at embarqmail.com>
To: "Brian Denley" <b.denley at comcast.net>
Cc: "Elecraft Reflector" <elecraft at mailman.qth.net>
Sent: Tuesday, September 07, 2010 11:08 PM
Subject: Re: [Elecraft] [K2] No Transmit Power


> On 9/7/2010 10:16 PM, Brian Denley wrote:
>> Don:
>> I brought home a DSO5054A (very nice 500 MHz Agilent scope!) and I was 
>> able
>> to take the better measurements.  My measurements were in P-to-P but I 
>> have
>> divided them by 2.8 for RMS comparison:\
>> (all measurments Keydown)
>>
>> 1.)    VPWR line (pin 2 of U8 on control board):    5.0 volts        this 
>> is
>> HIGH
>>
>> 2.)    Xmit Mixer Output (pin 4 of U10):    28 mV
>>
>> 3.)    Buffer Output (pin 6 of U9):    121 mV
>>
>> 4.)    Band-Pass Filter Output (W6):    42 mV
>>
>> 5.)    T-R Switch #1 Output (anode of D1):    41 mV
>>
>> 6.)    Pre-Driver Output (collector of Q5):    34 mV           this seems
>> LOW

>>7.)    Driver Input (base of Q6):    34 mV

>>8.)    Driver Output (collector of Q6):    179 mV                this is 
>>VERY LOW

>>9.)    PA Inputy (base of Q7):    80 mV                               this 
>>seems HIGH

>>10.)    PA input (base of Q8):    80 mV                              this 
>>seems HIGH

>>11.)    RF Detector Input (anode of D9):    143 mV          this is VERY 
>>LOW

>>on my own I also measured:

>>12.)    base of Q5:    43 mV

>>13.)    out of C107    43 mV

>>all of the DC voltages in column 1 on page 17 are normal