[Elecraft] [K2] No Transmit Power

[Don Wilhelm]

  Brian,

DON'T DO THAT!
If the K2 is developing any power, it will not do it for long without a 
50 ohm dummy load.  The PA transistors can go "poof" in a hurry when 
operated into an open circuit - yes, the small antenna wire is an open 
circuit.

73,
Don W3FPR

On 9/19/2010 10:39 PM, Brian Denley wrote:
> ?I should add:  If I connect a small wire to my K2 antenna and press tune,
> it shows a strong signal on any of my receivers at that frequency.  So
> somethings coming out of the K2.  Either the ouput signal is low OR the K2
> RF detector just doesn't measure it correctly for the ALC circuit.
> Brian Denley
> http://home.comcast.net/~b.denley/index.html
>
>
> ----- Original Message -----
> From: "Brian Denley"<b.denley at comcast.net>
> To:<don at w3fpr.com>
> Cc: "Elecraft Reflector"<elecraft at mailman.qth.net>
> Sent: Sunday, September 19, 2010 10:26 PM
> Subject: Re: [Elecraft] [K2] No Transmit Power
>
>
>> ?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
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