Posts by SV1BDS

PA3FYM The available frequency generator has relative high phase noise when used for near 25 MHz creation for reference for LNB and the resulted received signal has very low SNR. So when I will have a very low noise genarator for near 25 MHz I will do the experiment. One solution I thought is to divide the signal using a MB506 2.4 GHz divider or a similar solution that I have available.

PA3FYM I have not drink coffee yet....

PA3FYM 25,78 is greater than 25 MHz. Is it correct?

Hi, with SDR-Console , Amstrad F101 , 60 cm offset disk, I have 34 dB SNR at 739 (as measured by the latest version - not the difference of levels). SV8QG with a larger disk and unmodified Octagon LNB has 40 dB SNR. I will try to inject frequency to archive 430 MHz and also 950 MHz to see the differences. PA3FYM do you have wobling?

Hi, up converter from 28 MHz and IC735 to drive the roof upconverter at 430 MHZ with MAR8,SBL1,BPF 430 MHz, MAV11.

Hi, I am interested for this project but for the moment I do not have WB capabilities.

Hi, a down converter from 739 MHz to 28 MHz in a surplus box. It is a 739 BPF, a SBB5089 MMIC amplifier (worked better that so called SPF5189 from eBay) a SBL1 and a circuit for 50 ohm termination at 28 MHz. With H polarization the CW beacon is clearly heard !!!

Hi, a 4 way 10 MHz (not only) splitter was finnaly build in a recycled box. The attenuation is 8 dB and isollation is 12,5 & 23 dB between output ports.

PA3FYM If you worry about being checking every 20 sec that is fast for increasing it is also the same fast for decreasing ... The only I think that maybe had to be improved is the 64 check to be 50.

PA3FYM I have seen that with stable temperature the OCXO needs about half an hour to stabilize. When I have the aircondition off the GPSDO can reach high TC. When it is on it can not reach more than 200. My explanation is that it has flaps that are variyng the temperature and the OCXO can not reach high TC values. When aircondition is off it reach easy values as 1024. I believe that you will not have problems with 'faster' TC increase as it monitors the DEMA and if this become >16 it slows down the TC. I have never seen NoLock at startup period (after first lock...) even when I start the OCXO cool. I have initially try to 'panish' with >>3 only but did not work. Then I see that DEMA takes high values and when I see this I slow down TC before it loose lock. Sometimes the DEMA increases to as high as 30 and then the TC is dropped without loosing lock. With this code I have faster converge without loosing lock. At least I have not yet a case.

Hi, updated block diagram.

PA3FYM Hi Remco, it seems that the code is working. It slowes down from 1024 to a value that have TC <16 without loosing lock . I observed the frequency relative to Cesium and no importand jums was seen. I send you at email the modified code. I check every 20 sec (so a change is occured immidiately after the banner you added) and I check for dema >= 64 and then I divide by 2 as when it loose clock. I try without the 64 , with >>3 at >16 but it loosed lock.

Quote from PA3FYM

OK, I have limited TC to max 1024 (also because I couldn't believe that it could be reached, but you reached it anyway : -)

It costs me more to find a better OCXO that yours

PA3FYM Hi Remco, Lars says that he had problems with OCXOs when using temperature coefficient. I think to modify your routine to set a stable every x sec to check (about 15 to 30). Also to lower more aggressively that increasing. Alternatively idea is to check for bigger dema than 16 and apply greater TC decreases. Any idea for a number to check? Also I think that exist a min,max TC limit that can be used to your routine. TNX again !!!

PA3FYM Yes I have the same opinion : the software reacts but not as fast enough as required. I have noticed the high TC that archived and it seems that it is very stable. Even if it is a breidboard construction it is stable. I have noticed the 1024 TC and I can not believe it ! will try to see if the c parameter have any result. A lot of time and a lot of aircondition on off HiHI. That what I will propose to you to put an LCD in the code but you write it allready ...TNX again !!!

PA3FYM You have an (TWO NOW ..) email regarding aircondition testing...

Hi, GPSDO in a box.

Hi, the design phase of Lars GPSDO is completed. A *3 xtal filter is added to eliminate the harmonics. A 470 ohm resistor between the OCXO and the xtal filter increase the isolation of load, adapts the Z of the filter and give the proper level of drive to the MAV11, which gives full output.The first QSO with GPSDO is done. The result is increased SNR compared with initial xtal of LNB. No important jumps occurred when it loose lock for a while. A reset button it will be added to start from the beginning if it can not lock quickly. Also another HC390 was added and now can provide 1,10,100 KHz,1,5MHz at TTL levels for PLL reference. A 8 way splitter for 10 MHz is now in the design phase.

PA3FYM I put a LM35 but it loose lock even at relative low TC. I tested with box closed.

PA3FYM Using your software:

time ns dac temp status diff_ns filtX10 tc filt timer1 temp1 dema

31900 -11 33348 0.0 Locked -10 5067 821 410 25060 736 -6 96 5177 33349 0.0

31901 -8 33348 0.0 Locked 3 5067 821 410 25060 744 -8 97 5245 33349 0.0

31902 -4 33348 0.0 Locked 4 5066 821 410 25060 736 -8 98 5190 33349 0.0

31903 -4 33348 0.0 Locked 0 5066 821 410 25060 748 -8 99 5113 33348 0.0

31904 -4 33348 0.0 Locked 0 5066 821 410 25060 743 -8 100 5167 33348 0.0

31905 -1 33348 0.0 Locked 3 5066 821 410 25060 752 -8 101 5117 33348 0.0

31906 -4 33348 0.0 Locked -3 5065 821 410 25060 743 -6 102 5126 33348 0.0

31907 -8 33348 0.0 Locked -4 5065 821 410 25060 736 -6 103 5143 33348 0.0

31908 -1 33348 0.0 Locked 7 5065 821 410 25060 752 -6 104 5093 33348 0.0

31909 -4 33348 0.0 Locked -3 5065 821 410 25060 737 -4 105 5073 33348 0.0

When I open the aircondition it looses clock. I will send you the captured data to your email.