Re: [K2] K2 base low xmit power on all bands @ > 10 watts

Posted by Don Wilhelm on Feb 19, 2019; 4:21pm
URL: http://elecraft.85.s1.nabble.com/K2-K2-base-low-xmit-power-on-all-bands-10-watts-tp7649071p7649072.html

Mike,

First, you should not take output from the lower BNC jack when the
KPA100 is installed.  All RF must go through the KPA100 wattmeter for
proper power control.  That is why your power output at 5 watts is
excessive.  Put a boot over the lower panel BNC jack as a reminder that
it should not be used (unless the KPA100 is physically removed - along
with all 4 cables).

As for the higher power output, it sounds like your KPA100 wattmeter is
not properly calibrated.  Go to the KPA100 manual and turn to page 49.
Do the SWR Bridge Null Adjustment and the Power Calibration (R26 and
R27) so your KAT100 power is equal to that shown on the LP-100.
You must use a good 50 ohm dummy load (not an antenna) to insure accuracy.

73,
Don W3FPR

On 2/19/2019 11:03 AM, K5MMH wrote:

> Hello All,
>
> Let me first state that I do not know how long this condition has existed. I
> recently added an LP-100 watt meter to my shack and have noticed low
> transmit power on all bands (10 thru 160) when power is set to 10 watts or
> greater. I have an KPA100, and with it installed, I see no more than 60 to
> 70 watts max. My K2 is S/N 3010, and I built it new along with all of the
> add-ons. To provide the values listed below I removed the KPA100, and
> connected the LP-100 (recently re-calibrated by Larry Phipps) directly to
> the K2 base BNC antenna connector, with a DL1 dummy load on the load side of
> the LP-100 coupler. For input power, I am using a 13.5 VDC  50A power
> supply, supplying power to the K2 via barrel jack J3. With power set to 2
> watts, I am reading 2+ watts on the LP-100 on all bands. With power set to 5
> watts,  I am reading 5+ watts on all bands. Increasing power to 10 watts
> results in the following values (and the internal K2 watt meter coincides
> with these values) :
> 10m = 9.60w @ 2.56A current draw (seen on the K2 internal watt meter
> display)
> 12m = 8.80w @ 2.04A
> 15m = 9.10w @ 1.74A
> 17m = 9.40w @ 1.80A
> 20m = 9.40w @ 1.92A
> 30m = 9.20w @ 3.14A
> 40m = 10.10w @ 2.76A (the exception, as 40m is above 10w)
> 80m = 7.20w @ 2.70A
> 160m = 7.00w @ 3.12A
>
> When power is further increased to 15 watts, these are the readings:
> 10m = 12.10w @ 3.00A
> 12m = 10.60w @ 2.24A
> 15m = 10.10w @ 2.30A
> 17m = 11.90w @ 2.34A
> 20m = 11.50w @ 2.50A
> 30m = 10.00w @ 4.00A
> 40m = 9.20w @ 4.10A
> 80m = 7.40w @ 3.80A
> 160m = 7.30 @ 4.00A
>
> I have gone thru the 40m transmitter alignment and the transmitter alignment
> steps outlines on pages 72 and 74 of the manual. I also ordered and just
> replaced (two days ago) the PA transistors thinking this was my problem.
> But, the issue persists.
>
> Any assistance will be much appreciated.
>
> 73
>
> Mike Harang
> K5MMH
> Franklinton, LA.
>
>
>
>
>
>
>
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
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