Re: Frequency Stability


Vernon Matheson
 

Thanks Hans...I redid the order of tx as you said and used park mode 2 @ 150
Mhz plus the small heat sink and all I see is zeros ( just like my bank account) LOL! So success as it also removed the small curl on the start of each dit and dah in the qrss signal. Many thanks for your help.

Vernon

Sent from my BlackBerry 10 smartphone on the Rogers network.
From: Hans Summers
Sent: Friday, November 10, 2017 4:40 AM
To: QRPLabs@groups.io
Reply To: QRPLabs@groups.io
Subject: Re: [QRPLabs] Frequency Stability

Hello Vernon

The idea of the 150MHz is that it keeps the Si5351A "busy" while not transmitting, which keeps it warm; then when it starts transmitting, it is already warm and there is not much temperature change. Sometimes 150MHz is too high and causes a drift in the other direction, and needs to be reduced for that reason. It takes some experiment to get it right. But I always found best results on a multi-band Ultimate3S by having 10m first, then 15, 20m, 30m etc going down in frequency. 

73 Hans G0UPL

On Thu, Nov 9, 2017 at 6:22 PM, Vernon Matheson <vmath@...> wrote:
Thanks Hans...would I reduce the 150.000.000 maximum frequency by 28.200.000? 
 
On 11/09/17 10:54 AM, "Hans Summers" <hans.summers@...> wrote:
Hi Vernon

I suggest putting the sequence of the bands the other way around: start with the highest frequency and then step down. 

Park Mode 2 is useful in the gaps between transmissions but makes very little difference if the gap is only 8 seconds. So use Park Mode 2 for the long wait at the end of calibration and before the Mode 0] configuration starts. Have it sequence through starting at the highest frequencies then stepping lower. 

73 Hans G0UPL

On Thu, Nov 9, 2017 at 5:35 PM, Vernon Matheson <vmath@...> wrote:
 Hi all,
 
I have been trying to reduce the drift on my wspr tx when running 5-6 bands. I seem to be able to get one band with zero drift and the next band in sequence has some drift. See the data for 20m versus 30m below
 
I have attached a small heat sink on the 27mhz xtal as suggested but am wondering about park mode. U3S is also in a qrp labs case.
 
If I set to mode 2 and say 149.000.000 as suggested it doesn't change much.
 
Would I be better to use park mode #1 and then 149.000.000 for a frequency.
 
Vernon
 
Timestamp Call MHz SNR Drift Grid Pwr Reporter RGrid km az
 2017-11-09 14:24   VA1VM   14.097148   -22   -3   FN85ij   0.2   G4ZFQ   IO90ir   4509   59 
 2017-11-09 14:24   VA1VM   14.097165   -24   -2   FN85ij   0.2   F4GUK/SDR   JN18et   4828   61 
 2017-11-09 14:24   VA1VM   14.097153   -20   -3   FN85ij   0.2   K9AN   EN50wc   2102   263 
 2017-11-09 14:24   VA1VM   14.097157   -2   -3   FN85ij   0.2   W9HAM   EN64   1865   275 
 2017-11-09 14:24   VA1VM   14.097156   -22   -3   FN85ij   0.2   G0DLV   IO70ru   4286   60 
 2017-11-09 14:24   VA1VM   14.097150   -22   -3   FN85ij   0.2   G0LUJ   IO83ls   4305   55 
 2017-11-09 14:24   VA1VM   14.097157   -21   -3   FN85ij   0.2   KA4PKB   EN41kf   2287   268 
 2017-11-09 14:22   VA1VM   10.140154   -26   0   FN85ij   0.2   SWLKCL   FN03ip   1281   267 
 2017-11-09 14:22   VA1VM   10.140156   -9   0   FN85ij   0.2   SWLNXZ   FN13co   1165   265 
 2017-11-09 14:22   VA1VM   10.140153   -22   0   FN85ij   0.2   K9AN   EN50wc   2102   263 
 2017-11-09 14:22   VA1VM   10.140152   -18   0   FN85ij   0.2   VE3YX   FN16fd   1107   279 
 2017-11-09 14:22   VA1VM   10.140160   -22   0   FN85ij   0.2   VE3BSB   FN14uv   1020   272 
 2017-11-09 14:22   VA1VM   10.140153   -20   0   FN85ij   0.2   K4COD   EM73sc   2266   240 
 2017-11-09 14:22   VA1VM   10.140154   -18   0   FN85ij   0.2   K1BZ/3   FM19ne   1311   243 
 2017-11-09 14:22   VA1VM   10.140150   -21   0   FN85ij   0.2   N4CDN   FM18iu   1362   243 
 2017-11-09 14:20   VA1VM   7.040163   -27   0   FN85ij   0.2   N4TVC   FM18is   1367   242 


 



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