U3S - xmit frequency is 200 Hz higher than indicated on display


John Canfield <bucket@...>
 

First off, my apologies if this has been answered/discussed/in the manual. Some kind soul emailed me saying I was transmitting 100Hz outside of the WSPR frequency range on 30M, I always thought I didn't get very many reports due to my antenna, etc. I dropped my xmit frequency by 100Hz which put me right at the top of the WSPR range and started getting a bunch of reports. I dropped the frequency another 100 Hz (200 Hz in total) which put me right in the middle of 30M WSPR. Now I'm getting >= 20 spots every hour.

This U3S has a GPS that is successfully talking to the U3S and I was under the impression that with the attached GPS, there was no need to fiddle with the oscillator frequency. I could lower the oscillator frequency by 200 Hz but then what's the point of having the attached GPS? What don't I understand here? Again - sorry if this is a dumb question.
--
John, WB5THT


Klaus Beckers
 

Hi John
  This is Klaus, DL2QB (also WN2Z). I am not sure if I fully understand your question. Just connecting the U3S with a GPS and then doing nothing more won't guarantee that the U3S is working on the proper frequency indicated by the display. Unlike the procedure with e.g. the QCX QRP tfansceiver where you onxe set the proper osciallting frequncy in the beginning and leave the QCX alone more or less, on the U3S you must set up the correcting frequncy calibration after every cycle of WSPR transmissions- So you should specify how often and too what degree the U3S is commanded to compare the frequency of your master oscillator (not the one that controls the clock for the processor) with the standard it has just received   (pps pulses) from the GPS unit. You can specify in what steps and how often your oscillator has to be compared with the GPS standard and after that has been done, the U3S will correct the U3S oscillating frequency accordingly. After such a correcting cycle you will see a short message on the display that says -003 or +015 or 000 which will tell you how many Hertz (Hz) the frequency has been corrected. If you have your U3S close to a window pane you can easily see the drift of the xtal oscialltor due to the change in environmental temperature. If you don't set up this calibration cycle like described in the U3S manual, the xtal oscillator may drift so far that the final transmitting frequency is off -and in worst case- outside the WSPR band. My aplogies if I have not always found the proper wording, English ist not my mother language and may be I also did not fully understand your problem.

73 from Cologne
Klaus
DL2QB


John Canfield <bucket@...>
 

Thank you Krause, your English is better than some with English as a first language ;-) I have set the U3S up to do a calibration every few minutes, the oscillator must be stable because there is usually no change required ( = ).
--
John, WB5THT


Hans Summers
 

Hi John


What are you using for the parameter "Cal {Time Step}"?

73 Hans G0UPL 

On Mon, Apr 15, 2019, 00:10 John Canfield <bucket@...> wrote:
Thank you Krause, your English is better than some with English as a first language ;-) I have set the U3S up to do a calibration every few minutes, the oscillator must be stable because there is usually no change required ( = ).
--
John, WB5THT