[Elecraft] K3 Power-hunting on FT8

[Rick NK7I]

Pete,
I would suspect that the local ham didn’t account for you overdriving his receiver (or test set) which would explain why an underdriven signal appeared cleaner (no overload).  Had he attenuated your 4 bar signal, it would have been clean, I’m 100% certain.

A full audio supplied (just shy of ALC) K3  is clean.  I’ve had mine monitored several times with real test equipment, to make sure before I trusted it at QRO levels (and checked again in case there was an RFI distortion).  On some radios harmonics will appear, but they are internal to the radio, not really on the air (overdrive distortion).

It will remain as clean as the audio, up to the point the ALC begins to kick in; then it goes bad like any other radio.  That’s the fault of ALC, not the radio.

I DX, it’s about the only thing I do on ham radio.  Most of the time at legal limit with a high gain antenna (helps to be LOUD, get heard, make the contact, fight less) and over the past several years FT8 has been the mode of choice by DX teams (limited staff, fast, one op can work 2-3 bands at a time, efficient and dreadfully boring).  Had there been an issue, I would have heard about it by now; my station is one of several hundred potent signals on the band.

But, you have your answer why it’s hunting power and can choose to operate as you see fit as long as you remember that the K3 will try to ‘pull’ more audio in order to obtain the power setting, which may be that it pulls in sounds and noises (power supply, signals on other sound card or rig noises) not normally heard (and looks poor on the output as a result).

My suggestion:  As stated prior for the how, 4 bars of audio drive with the 5th barely flickering (WSJT-X at max) and leave it all alone.  Using audio drive on a modern rig as an RF output control is misusing the rig and clutters up the air.  Leave the ‘power setting’ on WSJT-X at MAX; recheck the collections of settings periodically (and ALWAYS after a Windows update, they often do NASTY things to audio and USB port settings).

The WSJT-X control is akin to reducing receive signal levels by trimming feet of antenna off, instead of using the RF gain control.  It has the same results but it’s just not the correct method.

If you do this, you’ll find that the clean output at the power you actually set the radio for, will allow other DXCC conclusions in very short order (because you’re loud and clean).

The choice is yours.

73,
Rick NK7I

> On Jul 20, 2023, at 7:33 PM, Pete Smith N4ZR <pete.n4zr at gmail.com> wrote:
> 
> OK guys - rather than reply individually, let me try to pull everything together in one message.
> 
> In a previous effort at FT8 I followed the standard advice to set the power slider in WSJT-X (on the lower RIGHT side) so that my K-3 showed 4 bars on the ALC meter, just below the threshold for ALC starting, and that seemed to work fine.  Then a technically-qualified local ham showed me spectrum analyzer images of a K-3 at 4 bars versus at no bars, and the difference was startling - the no bars signal was clean and narrow, while the 4-bars signal looked like some of those SSB sigs we hear during contests, wide and with many artifacts.  I am not going to identify my source here, but I'm fairly sure he reads this reflector, so maybe he'll join the discussion
> 
> Anyway, I'm kind of at sea - WSJT-X works fine with no bars - I've finished 12 and 17M, as well as digital DXCC in the last few weeks, following his advice.  But the hunting typically takes almost 20 seconds of transmitting - roughly 1 1/2 FT-8 cycles - to reach full power - and happens every time I change bands, which puts me behind the curve if I switch bands, see someone I need, and have to spend 1 1/2 transmit cycles getting up to full power before I can call him effectively.
> 
> 73, Pete N4ZR
> 
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