[Elecraft] K2 BFO Test Problems

[Craig Young]

Hello again,

I've continued my troubleshooting efforts but the problem persists.   
I had reflowed all connections except those of X3, so I removed L33  
and R116 to do so.  Everything appears to be well connected and I  
don't see any shorts.

I checked the DC voltages on U11 using the internal probe and have  
the following values:

Pin 1:	1.4
Pin 2:	1.4
Pin 3:	0.0
Pin 4:	4.8
Pin 5:	4.8
Pin 6:	5.6
Pin 7:	5.0
Pin 8:	6.0

I used the RF probe to check the voltages with the following results:

U11, pin 6:	0.74
TP2:		0.024

The DC voltages for U11 pins 6 and 7 are a bit low and the RF probe  
values are on the edges.  Is it possible that U11 is bad?

73,

Craig


On 18 Feb, 2007, at 10:46, Craig Young wrote:

> Hello to the group.
>
> I am currently working through the Alignment and Test, Part II and  
> have run into the following issue.  When I perform the BFO Test, I  
> don't get the proper range.  The set of values I get are:
>
> BFO High Freq.: 4917.31 kHz
> BFO Low Freq.:  4916.97 kHz
> Range: 0.34 kHz
>
> The documentation states that if the BFO range is less than 3.6  
> kHz, the varactor diodes (D37 and D38) or the crystals (X3 and X4)  
> may be incorrect.  However, I've verified them and they are  
> correct.  I've also gone around looking for bad soldering (cold  
> joints or bridges) and didn't see anything obvious.  I've checked  
> the resistors and capacitors in the BFO section and they appear to  
> be correct.
>
> Does anyone have any ideas of where I should look next?
>
> 73,
>
> Craig AC6NN
>
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