[Elecraft] [MM] XG1 signal problem

[Don Wilhelm]

Brian,

Those resistances are close, but admittedly a bit on the low side - but 
not enough to declare those the root of your problem.
Your description sounds like you get the 1 uV output no matter which 
position the switch is in.  The attenuator consisting of R6, R7 and R8 
should be out of the circuit when in the 50 uV position.
Examine the schematic and check the switch for proper operation.  The 
schematic shows the switch in the 50 uV position.  If the attenuator is 
in all the time, you will have only a 1 uV signal level.  If you are 
having trouble following the schematic, then measure the resistance from 
the junction of R4 and R5 to the junction of R6 and R8 when the switch 
is in the 50 uV position - the resistance should be very high.  If it is 
not, look for solder splashes (and excess solder) or the possibility of 
a bad switch.

73,
Don W3FPR

Brian - N5BCN wrote:
> Hello all,
>
> When attempting to calibrate my K2's S-meter with a XG1, I discovered the
> XG1 itself is having a problem.  I verified this by connecting it to a
> working IC-7600.
>
> The signal output on it, although heard, is very weak.  Adjusted for
> on-frequency, the s-meter reads about S2 or S3.  Touching the XG1 can get
> the signal up to about S4 or S5.  Switching between 1 uV and 50 uV makes no
> apparent difference in signal strength on the s-meter.
>
> Resistance checks on the XG1 and found some problems:
>
> Resistance from the following junctions to ground:
>
> U2, R1 = 50 k Ohms (should be 57-63 k Ohms)
> C4, R3 = 50 k Ohms (should be 57-63 k Ohms)
> R1, C1 = 54 k Ohms (should be 67-73 k Ohms)
>
> Checked all component placements and solder joints, no obvious problems. 
> Reheated all solder joints (twice now) just in case; no improvement.
>
> My next step is to measure all the resistor and capacitor values.
>
> Do these symptoms jump out anybody as something obvious (bad xtal or other
> component)?  Any suggestions will be most appreciated.
>
> 73
>
> Brian - N5BCN 
>   
>