KX1 kit - zero power on transmit

[Scott Anderson]

Hi all,

I'm working on getting KX1 2846 up and running and have run into an issue
with the transmit testing.  I get zero power output into a 50 ohm dummy
load.  As it is right now, it is built only as the 20/40 meter with no ATU
installed (the base kit).

I have run through the troubleshooting table and made sure:

1.  R4 is fully clockwise (and there is a difference in level to a monitor
KX3 nearby when this is adjusted).

2.  J7 is jumped between pins 1 and 3

3. T1, L3, L1, and L2 are wound correctly and all have resistance of less
than 1 ohm.

When measuring the DC voltages across the transmitter:

Q1 - (D) 13.85; (G) 0.31; (S) 1.61
Q4 - (E) 0.23; (B) 0.95 [with power out via the watt meter during
measurement]; (C) 2.46
Q5 - (E) 3.71; (B) 2.45 [with power out during measurement]; (C) 13.85
Q6 - (C) 13.85

The Q5 emitter seems to be high with the other values close to those listed
in the KX1 manual.  I'm not sure what to make of the power out during the
measurement other than a poor connection somewhere.

I'll be contacting Elecraft for some help with the troubleshooting, but
thought I'd ask the group in the mean time.

Any suggestions would be appreciated.

Thanks,

Scott - W1ZU
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[Don Wilhelm-4]

Scott,

Yes, the emitter DC voltage at Q5 is higher than it should be - normal
is in the range of 2.0 to 2.4 volts depending on whether the KX1 Power
Mod has been installed or not (do not install it until you have verified
some reasonable power output).

I would suggest you check the soldering of R11 and R10 since those set
the DC bias point for Q5.  Also check the value and soldering of C41.  
That capacitor bypasses R10, so that for purposes of RF, only R11 is
present in the Q5 emitter path.

Do you have capability to measure the RF voltages at the various
stages?  An RF probe or an oscilloscope with a 10X probe will do fine.  
If so, let me know which and we can check the RF voltage at each stage
to determine the point of failure.  I know that is not detailed in the
KX1 troubleshooting section, but I have 'normal' RF voltages for each
stage of the KX1 transmit section, or I can verify with my testbench KX1.

73,
Don W3FPR

On 11/23/2014 6:35 PM, Scott Anderson wrote:

> Hi all,
>
> I'm working on getting KX1 2846 up and running and have run into an issue
> with the transmit testing.  I get zero power output into a 50 ohm dummy
> load.  As it is right now, it is built only as the 20/40 meter with no ATU
> installed (the base kit).
>
> I have run through the troubleshooting table and made sure:
>
> 1.  R4 is fully clockwise (and there is a difference in level to a monitor
> KX3 nearby when this is adjusted).
>
> 2.  J7 is jumped between pins 1 and 3
>
> 3. T1, L3, L1, and L2 are wound correctly and all have resistance of less
> than 1 ohm.
>
> When measuring the DC voltages across the transmitter:
>
> Q1 - (D) 13.85; (G) 0.31; (S) 1.61
> Q4 - (E) 0.23; (B) 0.95 [with power out via the watt meter during
> measurement]; (C) 2.46
> Q5 - (E) 3.71; (B) 2.45 [with power out during measurement]; (C) 13.85
> Q6 - (C) 13.85
>
> The Q5 emitter seems to be high with the other values close to those listed
> in the KX1 manual.  I'm not sure what to make of the power out during the
> measurement other than a poor connection somewhere.
>
> I'll be contacting Elecraft for some help with the troubleshooting, but
> thought I'd ask the group in the mean time.
>
> Any suggestions would be appreciated.
>
>

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