[Elecraft] KX1 lower power only on 40?

[Don Wilhelm]

Dan,

With a 13.8 volt power supply and working into a good 50 ohm dummy load 
(without the KXAT1 installed) you should have at least 3.0 watts on all 
bands (I normally expect 3.5 watts or more).  Measure with an external 
wattmeter that is has known accuracy at low power - many wattmeters with 
a 20/200/2000 watt range switch are inaccurate at low powers and will 
typically read lower than the actual power. That is typical of analog 
meters, many with digital readouts are not as bad in this respect.

While 40 and 20 meters usually have lower power output than 80 or 30 
meters, yours is extremely low.
You *will* find the problem is on the Low Pass Filter board.
Check it very carefully for toroid leads that are not well tinned and 
soldered.  If you see any evidence of wire enamel on the solder side of 
the board, that lead was not well tinned before installation and must be 
re-done.
Also make certain that the green lead on L2 that routes around to the 
back of the board is not contacting the red lead #4 - check both the 
front and back of the board.

You may have to remove the LPF board and re-wind the toroids.

73,
Don W3FPR

On 9/23/2013 12:24 AM, zan0416 wrote:
> Finished a brand new KX1 this afternoon, with ATU and 3080 module.
>
> Power output with 13VDC for all bands is as follows:
>
> 80  6.3 watts
> 40  1.7
> 30  4.0
> 20  3.0
>
> Clearly something is amiss with 40 meters.  I read somewhere to mess with
> the green windings of L2 on the 3080 module, but that didn't seem to do much
> other than make it worse.  The number of windings on all the toroids have
> been double-checked as correct.
>
> Anyone have any ideas where to go from here?  I don't have any test
> equipment except for a DMM.
>
> Thanks for any suggests you may have.
>
> Dan, n0da
>