[Elecraft] K2 Low Receive Sensitivity on High Power - Solved

[Jonathan Taylor, K1RFD]

The problem was with bypass cap C75 in the T-R switch.  It had a 
resistance of about 1.5 ohms across it.  Replacing it solved the 
problem.  Thanks for the tips.

73
Jonathan K1RFD

Don Wilhelm wrote:
> Jonathan,
>
> It is not a "well-known problem", but I believe you are correct to 
> assume the problem source is in the T/R switch.  I would suggest that 
> you check diodes D11, D12 and D14 first - or just replace them, 
> 1N4007s are plentiful and inexpensive.
>
> 73,
> Don W3FPR
>
> Jonathan Taylor, K1RFD wrote:
>> K2/100 # 2462, with all options except DSP.
>>
>> I've noticed just recently that when turning the Power above 10 W 
>> (and hearing the relays click), the receiver gain drops 20 or 30 dB.  
>> The receiver returns to normal sensitivity when the Power knob is 
>> returned to a lower setting.
>>
>> This must have starting happening only recently.  The rig is working 
>> fine on transmit at all power levels.
>>
>> Looking at the schematic, I suspect the the first place to look will 
>> be the T-R switch in the KPA100, but I thought I would post to the 
>> list to see if this is a well-known problem.
>>  
>
>