KX1 Power / Meter

[Jim - W6VAR]

I was just reviewing the power output on my KX1 on various bands and came up with the following results:

Band Int Batt Ext  Bat Ext w/Tuner Ext Bat on 40M Doublet 13.8 Volts
20 1.0 3.0 3.0 4.3 3.9
30 1.4 3.9 3.7 1.7 4.6
40 1.5 3.6 3.6 4.7 4.3
80 1.5 3.9 3.7 4.4 4.4


All were into a 50 ohm dummy load except for the 40M ladder line fed doublet that had a 1:1 balun near the radio. Power readings on a W1 watt meter.

Scenarios:
1. Internal Batteries Energizer Lithium 50 ohm dummy load, tuner bypassed
2. External SLA battery (about 12.5v) 50 ohm dummy load, tuner bypassed
3. Same but with tuner in line
4. External SLA battery with 40M doublet and tuned for a match.
5. 13.8V regulated power supply with 50 ohm dummy load

Initial readings seemed to make sense, but I had the following observations / concerns:

1. at 13.8 volts input, the power went over 4 watts on all but 20M, which was close at 3.9. Is this running too hot and should I reverse the power output mod or only operate at lower voltages?

2. The power output when the antenna was hooked up went up considerably on most bands. Why would this happen and should I be concerned?

3. There was a significant difference between the W1 and the KX1 wattmeters when the antenna was hooked up (several watts), whereas they were within a few tenths of a watt in the dummy load. Again, anything to worry about? What could cause this?

Thanks,

Jim - W6VAR

I have performed the modification

[Don Wilhelm-4]

Jim,

I would not be concerned with those power output levels.

The difference between the power displayed by the KX1 and the W1 when
using an antenna is due to significant SWR on the antenna feedline.  
Instruments placed at different places along the feedline will produce
different readings - yes, I know that is not supposed to happen with a
"true wattmeter", but then there is theory as opposed to practice.
If you want a better comparison, use exactly the same length feedline.  
Make a measurement with the W1, then disconnect the coax from the W1 and
attach it to the KX1 and make a reading on the KX1 with the ATU set to
CAL.  There is some timing variability in the KX1 display of SWR, so
take 3 readings and average them - if one is far afield of the others,
discard that one and average the other two.

73,
Don W3FPR

On 1/3/2012 3:54 PM, Jim - W6VAR wrote:

> I was just reviewing the power output on my KX1 on various bands and came up
> with the following results:
>
> Band Int Batt Ext  Bat Ext w/Tuner Ext Bat on 40M Doublet 13.8 Volts
> 20 1.0 3.0 3.0 4.3 3.9
> 30 1.4 3.9 3.7 1.7 4.6
> 40 1.5 3.6 3.6 4.7 4.3
> 80 1.5 3.9 3.7 4.4 4.4
>
>
> All were into a 50 ohm dummy load except for the 40M ladder line fed doublet
> that had a 1:1 balun near the radio. Power readings on a W1 watt meter.
>
> Scenarios:
> 1. Internal Batteries Energizer Lithium 50 ohm dummy load, tuner bypassed
> 2. External SLA battery (about 12.5v) 50 ohm dummy load, tuner bypassed
> 3. Same but with tuner in line
> 4. External SLA battery with 40M doublet and tuned for a match.
> 5. 13.8V regulated power supply with 50 ohm dummy load
>
> Initial readings seemed to make sense, but I had the following observations
> / concerns:
>
> 1. at 13.8 volts input, the power went over 4 watts on all but 20M, which
> was close at 3.9. Is this running too hot and should I reverse the power
> output mod or only operate at lower voltages?
>
> 2. The power output when the antenna was hooked up went up considerably on
> most bands. Why would this happen and should I be concerned?
>
> 3. There was a significant difference between the W1 and the KX1 wattmeters
> when the antenna was hooked up (several watts), whereas they were within a
> few tenths of a watt in the dummy load. Again, anything to worry about? What
> could cause this?
>
> Thanks,
>
> Jim - W6VAR
>

... [show rest of quote]

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