[Elecraft] K2 build - VCO control voltage 0 volts

[Harry Stone]

Strange indeed, and here is why, when I was messing with it just now
measuring again, I laid my arm across the case  and then I got voltage.
 Somewhere I had something shorting against the case.

I'm back on track now, VCO voltage is in spec for every band.  CAL PLL is
running now.  When it's done I will double check the bottom of the RF board
to make sure I don't have something sticking up too high.

Thanks again!
harry


On Saturday, October 26, 2013, Don Wilhelm wrote:

> Harry,
>
> That is quite strange.  I would examine your work carefully, particularly
> looking for lifted solder pads and/or solder bridges.
>
> 80 meters should have only C72 in the circuit. You should trace the VFO
> range select path with an ohmmeter by following the path in the schematic
> (checking for continuity) from K15 pin 3 through relays K15, K14, and K13
> to C72.  Relays K15 and K14 should follow the path shown by the closed
> contacts on the schematic while relay K13 should be "set" which means
> continuity between pins 3 and 4.
>
> 73,
> Don W3FPR
>
> On 10/26/2013 9:09 PM, Harry Stone wrote:
>
>> Well I spoke too soon.  I replaced that capacitor and now I have 0 volts
>> on
>> every band.   Any thoughts?
>>
>> thanx,
>> harry
>>
>>
>>
>>
>> On Saturday, October 26, 2013, Harry Stone wrote:
>>
>>  Don,
>>>       I know this isn't exactly your first rodeo, but that's still pretty
>>> impressive.  I have the wrong component installed at C73, I have a 4
>>> <point> 7 pF instead of a 47 pF.
>>>
>>> Bravo!
>>>
>>> thanx,
>>> harry
>>>
>>>
>>>
>>> On Saturday, October 26, 2013, Don Wilhelm wrote:
>>>
>>>  Harry,
>>>>
>>>> The thing in the VFO Range Select area that is common between 40, 30 and
>>>> 15 meters is C73,
>>>> Check its value - it should be 47 pF (marked 470).
>>>>
>>>> A low voltage at R30 indicates that there is not sufficient capacity in
>>>> the tuned circuit and the PLL/VCO is trying to increase the value of the
>>>> total capacity.  That means if C73 is the correct value, check its
>>>> soldering and the soldering of relay K13 pin 8.
>>>>
>>>> CAL PLL depends on having the 40 meter frequency range correct, so you
>>>> will not be able to do that procedure until you have the R30 voltage in
>>>> range on 40 meters (info 232 means the frequency read by the MCU is not
>>>> correct (yes there are other possible causes of info 232).  The
>>>> alignment
>>>> steps are sequential, so if one does not give correct results, you
>>>> cannot
>>>> skip to the next one without encountering problems.
>>>>
>>>> 73,
>>>> Don W3FPR
>>>>
>>>>
>>>> On 10/26/2013 6:13 PM, Harry Stone wrote:
>>>>
>>>>  My VCO control voltage is zero on 40,30, and 15 meters.  All other
>>>>> bands
>>>>> are within the normal range, all tests prior to these measurements
>>>>> passed.
>>>>>    When I try to run CAL PLL, I get info 232 even though I am on 40
>>>>> meters.
>>>>>
>>>>> What should I check first?
>>>>>
>>>>>
>>>>>
>>>>>  --
>>> Have old memories and young hopes.
>>>
>>>
>>
>

-- 
Have old memories and young hopes.