KX1 Receiver Deaf

[nlhouck]

I recently built a KX1 with 3080 and tuner options.  Initially I had low audio but resolved by fixing a missed solder joint.  With that done, It passed the initial alignment and all seemed fine.  With proper ear buds the audio level is actually a bit loud for me.  Unfortunately, unless I touch the circuit board near U6 the unit is deaf.  Touching the board brings the unit to life and the receive is pretty good.  I've resoldered everything in the area.  Also checked voltages at U6.  They 'seem' ok, but about 0.5 v higher than spec'd on pins 5 and 6.  I've removed the tuner ( which seems to work ) and replaced with jumper and tested with same results - deaf receiver.  Could it be a CAP, since I'm a pretty big capacitive load?

The build was fun and I'm learning a lot, but could really use someone to help me clear the cobwebs and work through this problem.  Thanks in advance for any help you can offer as I'm anxious to play on the air.  I don't want to operate the unit with my finger stuck on the circuit board, I might give people the wrong impression of ham radio operators.

73 de
KC2MJT
Nate Houck
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[Don Wilhelm-3]

Nate,

The most likley problem is that you may not be getting a signal from the DDS
to pin 6 of the receive mixer (U6).

Does it transmit with good power?  If not, check L4 and L5 with an ohmmeter
to see if they are open - they are easily damaged when installing them.

If it transmits, then check C3 for correct value and proper soldering.  If
you have an RF Probe (or can construct one), check the RF Voltage at U6 pin
6 - it should be greater than 70 mV to meet the mixer specs, but the usual
amplitude is half a volt of more.

73,
Don W3FPR

> -----Original Message-----
>
> I recently built a KX1 with 3080 and tuner options.  Initially I
> had low audio but resolved by fixing a missed solder joint.  With
> that done, It passed the initial alignment and all seemed fine.
> With proper ear buds the audio level is actually a bit loud for
> me.  Unfortunately, unless I touch the circuit board near U6 the
> unit is deaf.  Touching the board brings the unit to life and the
> receive is pretty good.  I've resoldered everything in the area.
> Also checked voltages at U6.  They 'seem' ok, but about 0.5 v
> higher than spec'd on pins 5 and 6.  I've removed the tuner (
> which seems to work ) and replaced with jumper and tested with
> same results - deaf receiver.  Could it be a CAP, since I'm a
> pretty big capacitive load?
>
>

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