[Elecraft] Low Power Output on 160 and 6 meters

[Russ Tobolic]

56" for the original cable is quite long. What gauge cable are you using?
Russ, N3CO

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  On Tue, Jun 25, 2019 at 10:05 AM, Everett via Elecraft<elecraft at mailman.qth.net> wrote:   Hi Jim,
You brought up a good point that I had not thought of and that is the voltage drop at the K3S itself. So I set up the voltage reading a the VFO B window and noticed that the voltage had dropped down to 12.1V when I keyed down, but the power supply said 13.7V at key down. So I shortened the power cable, by 32" and now it is 24" long. Now I see 13.1V at VFO B window and 100 watt on 160 meters and 105 watts on 6 meters. I increased the power supply voltage to 14V and now I see 13.3V at VFO B window, on key down and now 105 watts out on 160 and 110 out on 6 meters.
So to make a long story short, the K3S will put out over 100 watts on 160 and 6 meters if your power supply voltage is at 13.8 volts and you keep the power cord short. The additional 32" of power cord dropped the voltage by 1 volt on key down.
Everett N4CY


In a message dated 6/25/2019 7:50:32 AM Central Standard Time, Hamshack at N4ST.com writes:

I see the same output powers on my K3S.
Key down voltage is 13.4 volts on the VFO B display at maximum power out.
Elecraft offered to upgrade my PA chain for $100, but I'm not concerned
about ~1dB and is within spec for 6m anyway.
Glad that diode is in there.  I tested its function once.

_________ 
73,
Jim - N4ST


-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On
Behalf Of Don Wilhelm
Sent: Tuesday, June 25, 2019 08:31
To: EVERETT SHARP <everettsharp at aol.com>; elecraft at mailman.qth.net
Subject: Re: [Elecraft] Low Power Output on 160 and 6 meters

Everett,

What is your power supply voltage during transmit at 100 watts as measured
with the Alternate VFO B display?

With a solid 13.8 volt power supply voltage, you should see no lower than
12.7 volts (there is a diode drop inside the K3).

If lower, check the connections in the power cable for tightness.
The K3 power cable should run direct from the power supply.  Rigrunner and
other DC power distribution boxes can be reason for excessive voltage drop.

You can increase the power supply voltage up to above 14 volts to help - do
not exceed 15 volts.

73,
Don W3FPR

On 6/24/2019 6:51 PM, EVERETT SHARP via Elecraft wrote:
> I have three K3S and over the week-end I connected each of them to my Bird
watt meter, with a Dummy load. Each of K3S were updated to the current
Firmware and each had the 5 and 50 watt calibrations run.
> 
> What I found was all 3 showed from 80 to 90 watts output on 160 meters 
> and on 6  meters I saw 75 to 90 watts. All other bands showed 
> typically
> 105 to 110 watts. However, one of the K3S showed exactly 100 watts on all
bands except for the lower power on 160 and 6 meters.
> 
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