first post test and kx1 power issues

[IanMW]

Hi folks,

I've just finished building my base kx1 without options, planning to use it as my prime SOTA rig, (along with the rockmite 40 & SW+20 I have already used).

Construction and stage checks went fine, it emits rf and sounds fine on my big rig.

I've checked the output into a dummy load and homebrew rf probe which is "quite" accurate. To cut to the chase, I get more power on 20 meters than 40 meters, at 14 volts I have 2.9w and 2.6w respectively. Now this is fine but I read that 20 is normally lower than 40 for optimal clean signals. I've checked all my work, windings are correct and bunched up to 70% of diameter on L2.

Is this a problem or just component variability? I've still to see what I get at 9 volts, although it'll run from an 11.1 volt 3c lipo when SOTA.

I have one qso in the bag on 20 meters, 559 from France.

The receiver is very fb, and I love the qsk.

Just to recap, happy with the power out (I've worked N4EX from here in Scotland using 1.5 watts), just unsure about emisions.

73,
Ian, MM0GYX
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[Don Wilhelm-4]

Ian,

The greater power on 20 may be OK, it is difficult to tell from a
distance, but less than 3 watts gives me concern.  You can add the "KX1
Power Mod"  Change R11 to 4.7 ohms (or add another 10 ohm in parallel
with the existing 10 ohm resistor) and increase R30 to 33 ohms.  If you
ordered the KXB3080 option, those resistors are included.

I generally expect a KX1 to develop at least 3.5 watts on all bands with
a 13.8 volt poser supply, but recent kits have needed the power mod to
do it.

73,
Don W3FPR

On 4/15/2012 7:12 AM, Ian Watson wrote:

> Hi folks,
>
> I've just finished building my base kx1 without options, planning to use it as my prime SOTA rig, (along with the rockmite 40&  SW+20 I have already used).
>
> Construction and stage checks went fine, it emits rf and sounds fine on my big rig.
>
> I've checked the output into a dummy load and homebrew rf probe which is "quite" accurate. To cut to the chase, I get more power on 20 meters than 40 meters, at 14 volts I have 2.9w and 2.6w respectively. Now this is fine but I read that 20 is normally lower than 40 for optimal clean signals. I've checked all my work, windings are correct and bunched up to 70% of diameter on L2.
>
> Is this a problem or just component variability? I've still to see what I get at 9 volts, although it'll run from an 11.1 volt 3c lipo when SOTA.
>
> I have one qso in the bag on 20 meters, 559 from France.
>
> The receiver is very fb, and I love the qsk.
>
> Just to recap, happy with the power out (I've worked N4EX from here in Scotland using 1.5 watts), just unsure about emisions.
>
> 73,
> Ian, MM0GYX
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

... [show rest of quote]

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[AC8JW]

I have just assembled s/n 2626 and have found low power output. Mine is a two band version with no options.  With a bench supply, I get 4 Watts on 20M and 3 Watts on 40M into a dummy load. This measured with an electaft W1.  I will look again at my LP toroids, but looks like I may need to do the power mod.

[AC8JW]

I have just assembled s/n 2626 and have found low power output. Mine is a two band version with no options.  With a bench supply, I get 4 Watts on 20M and 3 Watts on 40M into a dummy load. This measured with an electaft W1.  I will look again at my LP toroids, but looks like I may need to do the power mod.

[Don Wilhelm-4]

What is your DC voltage?  The KX1 specification is 3-4 watts with 12
volts, so you are close to the spec right now.  If you have an antenna
analyzer, check you dummy load to be certain it is the same 50 ohm pure
resistive load on both bands.  Your wattmeter may also be frequency
sensitive - many are.

Yes, look at the toroids and the capacitor values in the LPF.

Don't push the power too far - the LPF componentscan be stressed with
power level much over 4 watts (that depends on the SWR).

73,
Don W3FPR

On 4/23/2012 1:11 PM, AC8JW wrote:
> I have just assembled s/n 2626 and have found low power output. Mine is a two
> band version with no options.  With a bench supply, I get 4 Watts on 20M and
> 3 Watts on 40M into a dummy load. This measured with an electaft W1.  I will
> look again at my LP toroids, but looks like I may need to do the power mod.
>
>
>
>
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