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Drift
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I changed from 150,000,000 to 149,000,000 with no appreciable change and went to 075,000,000 and was still getting drift of 2 to 4 (on 20m), so it looks like something's not quite there.? I'm not even sure there's progress, as these latter figures were from various stations rather than just the one as in the previous experiment.
It did not seem to change 40m's fairly sound 0 to the occasional -1. |
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I have the same results here. I see drift reported on my beacon when
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operating on 20 meters but once I go to other bands the drift goes back to zero. I admittedly have not tried changing the park 2 frequency from 150.000. I will try experimenting with that value and see what happens. I too was concerned that if I change this setting would it negatively affect the bands reporting zero drift, Tim KB2MFS<div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br /> <table style="border-top: 1px solid #D3D4DE;"> <tr> <td style="width: 55px; padding-top: 13px;"><a href=" target="_blank"><img src=" alt="" width="46" height="29" style="width: 46px; height: 29px;" /></a></td> <td style="width: 470px; padding-top: 12px; color: #41424e; font-size: 13px; font-family: Arial, Helvetica, sans-serif; line-height: 18px;">Virus-free. <a href=" target="_blank" style="color: #4453ea;">www.avast.com</a> </td> </tr> </table><a href="#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2" width="1" height="1"></a></div> On Thu, Nov 30, 2017 at 5:12 PM, TrueBlue <44-40@...> wrote:
I changed from 150,000,000 to 149,000,000 with no appreciable change and |
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Actually it isn't back to zero but the lower the freq. the less the
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drift. Maybe further adjustment will cure my drift here. Tim KB2MFS On Thu, Nov 30, 2017 at 6:37 PM, Tim Campbell <kb2mfs@...> wrote:
I have the same results here. I see drift reported on my beacon when |
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Hello The output frequency is a consequence, not the cause. The actual thing which drifts is the 27MHz reference oscillator of the synthesiser. The output frequency drifts as a consequence of that. The drift of the output frequency is the same as the 27MHz reference frequency, only when expressed in Parts Per Million (ppm). When expressed in absolute Hz terms, the drift is proportionately less on lower frequencies. You would expect half as much drift on 40m as you see on 20m. And twice as much drift on 10m as you see on 20m. Ok?? If you are transmitting through a sequence of bands, start with the highest frequency first in the sequence. At the end of the sequence leave enough time for the calibration to operate. Then configure Park Mode 2 and leave enough gap (say 1 minute) for the "park" to so its thing and "warm up" the chip before the first transmission starts. All of these things have inter-related effects.? Now concentrate on looking at the drift on the highest frequency. If you get the highest one right, then the rest will follow by themselves. First measure the drift with the "park" feature switched off. Say you see WSPR drift reports -3 or -4. Then switch it on in Park Mode 2, Park Frequency 150MHz. Now measure again. Say you see, drift +3 or +4. Now you know that the "park" feature has OVER-compensated for the drift; it has turned the negative drift into a positive one. It's a good sign :-)? ?In other words, during the "park" period, the frequency is too high, it is making the chip too hot, then when it starts transmitting on (say) 14MHz, it is cooling down, and drifting. You want "park" to get the chip to about the temperature that the 14MHz transmission would make. Remember, the trick in this is that the higher frequency, the more "work" the Si5351A chip is doing, the more current it consumes, which is dissipated as heat, making it warmer. So you can play with the frequency value, to control how much heat is produced in this "park" phase which keeps the chip "warm" until the next cycle starts.? Now you can play with lowering the Park Frequency until you see the drift comes down to near zero. I am not talking about reducing Park Frequency from 150MHz to 149MHz. You need to make drastic changes. Make it 75MHz. Then 40MHz. etc.? In my experience it has always been possible to use this, and the heatsink (e.g. coin) on the crystal, and some polystyrene around the synth to keep away warm air currents that may come from the BS170 PA transistors. I have always managed to get 0 Hz drift all over HF. I have even heard of people being able to use 2m WSPR with the Si5351A Synth kit, not needing to go to the OCXO version.? 73 Hans G0UPL On Fri, Dec 1, 2017 at 3:41 AM, Tim and Janet <kb2mfs@...> wrote: Actually it isn't back to zero but the lower the freq. the less the |
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Thanks for the great explanation Hans.? I think I understand now. 73 On Dec 1, 2017 12:29 AM, "Hans Summers" <hans.summers@...> wrote:
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By switching back to the "0" default I reduced drift to no worse than -3 to 3 ever (and usually much better) on any of my four bands which, as I understand it, is perfectly OK.? I imagine I will still have the RFI problem that I did originally, though.? If so, I'll try more experimentation and hope that the ideal Mode 2 frequency doesn't also produce RFI during idle at my receiver.
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¿ªÔÆÌåÓýYou don't say which mode you are talking about so I will assume that it refers to WSPR. The drift can occur at either or both ends. That is the transmitter and the receiver. An indication of 2 is nothing to worry about and will not make any difference to the range. Have a look at the drifts that other stations are seeing. Geoff On 20/02/2020 14:09, M0RON wrote:
A drift of 2 won't make any difference, if you build the ocxo kit and set it up carefully you will get 0 drift.? |
TrueBlue
M0RON
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