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Ah the good old days when I had an HQ-100AC that kept perfect time, and could turn the thing on.
Bob - W3DK
From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Wes Stewart via groups.io
Sent: Thursday, July 09, 2020 5:31 PM
To: Elecraft-K3@groups.io; Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Loses Time
I wouldn't expect it either. Nor would I accept it. (Actually, I would, I never use the clock anyway.)
On Thursday, July 9, 2020, 1:58:03 PM MST, Ray Maxfield <wa6vab@...> wrote:
So Your Happy with that ?
Un-expectable to me. Ray WA6VAB
And after all this trouble, I'm off by more than 7 seconds in 30 minutes.
Hey guys, just to add a little info that is hopefully useful to others, I took some pictures after going through this adjustment.
I'm using a 10x probe. 100x might be better but I don't know the circuit. I don't like loading down oscillators which could shift the frequency I'm trying to adjust. This is a cheap but very good $120 or so frequency counter from China and is being fed around the back with a 10MHz external reference (Trimble Thunderbolt GPSDO). This version is good out to like 6GHz. Not a sales pitch, but my HP units can't beat it for portability.
I needed to use a pretty skinny probe to reach back to the PCB. There's a hole for the tip of the probe to slip into if you can reach it (I couldn't with the original probe I tried). Definitely ground your probe shield somewhere. I'm clipped to a 1/4" jack for paddles. The little hole right next to it has the trimmer pot/cap (can't quite tell from out here). I used a ceramic blade adjustment tool, but plastic would likely be better only due to the fact that it's a tight fit and the ceramic isn't exactly bendy. Plastic probably would get around the scope probe a little easier -at least with mine.
My gut feeling is to recommend some minimum warmup time like 15-20 minutes before doing this adjustment. I turned it on and spent maybe 5 minutes looking around for the counter (lost the darn thing on the workbench -it's small!) I've already drifted about 0.12 Hz, but this kind of thing isn't exactly a precision oscillator with double ovens and all that. That said, I'm optimistic that my clock won't be terrible now.
Yes, sorry. The K3S clock trimmer TP is 32.768 Khz behind the VFO A knob.