[Elecraft] Help - K2 Higher Noise Level with X1 Selected

[VK1OO]

Don,

Still no joy with this problem.  I've resoldered most of the joints on 
the KSB2, checked the torroids etc  and have gone back and checked the 
filters with a noise generator and spectrogram.
What feature of the circuit would account for the increase in S meter bars?

Mike
VK1OO


On 10-Jun-12 10:12 AM, Don Wilhelm wrote:
> Mike,
>
> Two different filters - the FL1 OP1 filter is the one on the KSB2 
> board while the others are created from the variable bandwidth filter 
> on the RF board.  Since all but OP1 work correctly, it has to be the 
> OP1 filter on the KSB2 board.
>
> Oh, one more piece of info - when you remove the KSB2 board, the OP1 
> filter goes away, and the filtering defaults to a 2.20 bandwidth 
> filter from the filter on the RF Board.
>
> 73,
> Don W3FPR
>
> On 6/9/2012 7:54 PM, VK1OO wrote:
>> Hi Don,
>>
>> Wow, thanks for fast response noting it must be late there.
>>
>> I will do.  What conclusion can be drawn from X1 being affected, and 
>> not X2-4?
>>
>> Mike
>> VK1OO
>>
>> On 10-Jun-12 9:43 AM, Don Wilhelm wrote:
>>> Mike,
>>>
>>> It is on the KSB2 board somewhere.  Check everything on the end of 
>>> that board containing the filter crystals.  Check T1 and T2 to be 
>>> certain all the leads are well stripped,  tinned and soldered and be 
>>> sure there are no shorted turns on those toroids.  I recently 
>>> repaired a K2 that had the shorted turn problem because the builder 
>>> use a flame to burn off the insulation from the toroid wires and got 
>>> too much flame on the red T2 wires when he tried to strip the green 
>>> leads.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> On 6/9/2012 7:29 PM, VK1OO wrote:
>>>> Hi Don,
>>>>
>>>> We have a long weekend here, so I've been able to get back to this.
>>>> I reflowed RF board and KSB2 board, with no improvement.
>>>>
>>>> I then took out the KSB2, inserting the previously removed links 
>>>> and the capacitor (effectively returning radio to pre-KSB2 state).  
>>>> The noise problem on X1 goes away.
>>>>
>>>> Your thoughts on what to look at next would be appreciated.
>>>>
>>>> Mike
>>>> VK1OO
>>>>
>>>>
>>>> On 03-Jun-12 6:59 AM, Don Wilhelm wrote:
>>>>> Mike,
>>>>>
>>>>> If you do not find the solution re-flowing the solder on the RF 
>>>>> board filter area, the problem source may be on the KSB2 board in 
>>>>> the switching diodes and/or resistors at the filter end of that 
>>>>> board, so for completeness, reflow those connections as well.
>>>>>
>>>>> 73,
>>>>> Don W3FPR
>>>>>
>>>>> On 6/2/2012 4:24 PM, VK1OO wrote:
>>>>>> Don,
>>>>>>
>>>>>> The effect happens when the antenna is disconnected as well as when
>>>>>> connected.
>>>>>> And in SBB and CW
>>>>>>
>>>>>> SSB Filter Widths
>>>>>> X1 = OP1
>>>>>> X2 = 2.4
>>>>>> X3 = 2.1
>>>>>> X4 = 1.8
>>>>>>
>>>>>> CW Filter Widths
>>>>>> X1 = OP1
>>>>>> X2 = 0.7
>>>>>> X3 = 0.4
>>>>>> X4 = 0.1
>>>>>>
>>>>>> I assume something is going wrong in the 4.915MHz Variable Bandwidth
>>>>>> Crystal Filter.
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>