Re: K3 sudden frequency jump


Colin Smithers
 

A shot in the dark: did ambient temperature move and cause a change in a temperature compensated oscillator?

73, Colin G4CWH


On 21 Jun 2020, at 19:12, Ray Maxfield via groups.io <wa6vab@...> wrote:



Wes…… I agree.  As a Standards Engineer, I don’t See A Standard that Is 10 X ( normally Used) to Evaluate …..

The 4 Area’s you have Defined. 

 

Ray Maxfield WA6VAB

 

Sent from Mail for Windows 10

 

From: Wes Stewart via groups.io
Sent: Sunday, June 21, 2020 10:16 AM
To: elecraft-k3@groups.io; Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] K3 sudden frequency jump

 

You don't say what reference oscillator you have in your K3 or which synthesizer is installed.  I'm not a fan of fldigi so I am not comfortable commenting on its performance, but if I understand correctly, it is recording the beat note of the detected audio in SSB mode. The beat note is then subject to changes in 1) the incoming frequency, 2) the RX LO, 3) the RX "BFO" and 4) the soundcard sampling frequency.

 

Parameters 2 and 3 are derived from the K3 reference oscillator but (I think) not in a 1:1 relationship and SSB demodulation is a DSP process and not a real a real BFO driven mixer as in an analog RX.

 

My takeaway is that there are too many variables to point a finger at any one of them.

 

Wes  N7WS

 

On Sunday, June 21, 2020, 7:09:49 AM MST, Bob Benedict, KD8CGH <rkayakr@...> wrote:

 

 

I'm participating in the HamSCI Eclipse festival
https://hamsci.org/june-2020-eclipse-festival-frequency-measurement
which involves monitoring WWV using fldigi in frequency analysis mode. My K3 is sitting alone in the clear on a workbench powered by an Anstron 20 amp linear supply with a 17 amp hour lead acid battery backup (diode cut over type). I noticed this morning that although set to the same dial frequency, the received frequency as reported by fldigi jumped by about 10 Hz at some time last night. It then steadied at 10 Hz low. The K3 was in a closed room and not touched by anyone. Any thoughts about what happened and how to prevent this?

snippet of fldigi frequency analysis output - note change at UTC 11:48:26 and then some missing points

UTC

Freq

Freq Err

Vpk

11:48:19

10000000.143

0.143

0.0503

11:48:20

10000000.153

0.153

0.037964

11:48:21

10000000.162

0.162

0.04021

11:48:22

10000000.091

0.091

0.081219

11:48:23

10000000.011

0.011

0.137612

11:48:24

10000000.065

0.065

0.168657

11:48:25

9999999.122

-0.878

0.158187

11:48:26

9999996.705

-3.295

0.117768

11:48:27

9999993.314

-6.686

0.066463

11:48:28

9999989.708

-10.292

0.039115

11:49:17

9999989.89

-10.11

0.008997

11:49:55

9999989.675

-10.325

0.018503

11:49:56

9999990.454

-9.546

0.014056

11:49:57

9999990.923

-9.077

0.011183

11:49:58

9999990.84

-9.16

0.010979

 

Join Elecraft-K3@groups.io to automatically receive all group messages.