PA3FYM with the VC-TCXOs that I find it is not possible to have results suitable for QO100 using Lars GPSDO. As I can not find OCXO for 25 MHz and I found a 10 MHz OCXO with a range of about 2.5 Hz I will try this solution. I have to invert the VCO range.
Posts by SV1BDS
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I can't figure that '25 Hz' out, but the software is written for a reference with intrinsic short term stability (like an OCXO).
PA3FYM Can you try to see if it locks at 10 Hz up or down from center frequency ?
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PA3FYM Did you try the second link as the first is CMOS out ?
I have put the modified LNB at the roof and I was testing all 25 MHz osc to determine if some chirping is due to LNB PLL or modification but it is from the oscillator. Lars is going to be at a PCB as breidboard testing is completed. I try it with a homemade VC-XO as I did not have anything else. Have you tested also this Link ? I have build a couple of MAR8SM amplifiers with 30 dB gain and 200 mV out is not a problem I think. The main problem is phase noise and jitter at receiving as 9.75 GHz is about *5 of 1.9 GHz and as SV1IXP has told me a lot of years ago that the phase noise is the square of the ratio of frequencies. Do you have to propose a VC osc at 25 MHz for Lars?
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Need to improve:
1) phase noise (I have 20 dB SNR vs 30 dB SNR )
2) stability
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PA3FYM Thats what I plan to do next.
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13447 9 31584 1021 Locked -12 5165 4 2 14289 935 1076 -1 65535 65535
13448 23 31623 1023 Locked 14 5200 4 2 23670 941 1077 -1 65535 65535
13449 13 31611 1023 Locked -10 5170 4 2 32916 933 1078 -1 65535 65535
13450 28 31667 1023 Locked 15 5225 4 2 42336 942 1079 -1 65535 65535
it locks also here :
13639 18 26030 1013 Locked 14 5045 4 2 15428 931 115 0 0 0
13640 17 26085 1016 Locked -1 5110 4 2 21471 933 116 0 0 0
13641 5 26072 1013 Locked -12 5085 4 2 27484 927 117 0 0 0
13642 13 26097 1022 Locked 8 5110 4 2 33601 934 118 0 0 0
13643 -5 26043 1014 Locked -18 5035 4 2 39346 925 119 0 0 0
and here :
13778 -10 46935 943 Locked 1 4935 4 2 11088 877 1109 -1 65535 65535
13779 -27 46850 935 Locked -17 4835 4 2 20492 870 1110 -1 65535 65535
13780 -12 46860 946 Locked 15 4860 4 2 30103 877 1111 -1 65535 65535
13781 8 46940 955 Locked 20 4970 4 2 39965 892 1112 -1 65535 65535
13782 19 47028 965 Locked 11 5080 4 2 49286 901 1113 -1 65535 65535
It is every 25 Hz,.Any idea ?
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PA3FYM I have now about 250 Hz shift from h1 to h65500 at 25 MHz. So it is equivalent to 100 Hz at 10 MHz. This is 10 ppm at 10 MHz. So I have to reduce it to max 160 Hz at 25 MHz (6.5 ppm * 2.5). Am I wright ?
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1474 42 54564 963 Locked 14 5380 4 2 30902 909 76 0 0 0
1475 38 54573 963 Locked -4 5380 4 2 9395 907 77 0 0 0
1476 29 54570 958 Locked -9 5340 4 2 37607 897 78 0 0 0
1477 37 54583 957 Locked 8 5355 4 2 16076 906 79 0 0 0
1478 31 54585 959 Locked -6 5335 4 2 44688 902 80 0 0 0
with homemade voltage control xtal oscilator ...
PA3FYM I know that 50k DAC is far from 32k and diff_ns is no more than 30.
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PA3FYM Do I have to put also a 10K pull up to the reset?
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and now the community is anxious waiting to see
ur showp up on the transponder. everything seems to be well. 73 ROLF +
Hi,
This is a test setup. The VCO is missing and a standard oscillator is beeing used to test operation. The good news is that a 10 MHz output is available !!!
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Hi
I order one and I will post the results of using it as a VC-TCXO.
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Hi
DJ0MY Is TXC not TXP right?
It seems that it has a VC input pin #1 but no info provided. Has anyone test it? I plan to use it in Lars GPSDO directly at 25 MHz as VC TCXO.
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Hi,
The mod of the LSP04H (Globo - Opticum?) for external 25 MHz using 18 pF & 2,2 uH in series from input xtal pin to 75 ohm pin.
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Hi,
The FOX24B-25 is very sensitive to temperature and is useless for QO100 usage. It also jump frequency. The modification of LSP-04H (Globo-Opticum) here worked and I send from the 75 ohm coax the 25 MHz reference. But when I blow hot air to the FOX24B-25 it moves a lot of KHz the CW beacon that I monitor. The build in XTAL of LSP04H has much better perfomance than this TCXO.
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Hi,
To drop harmonics from the above circuit, a 30 MHz low pass is build based on SV1AFN desgin.
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Hi,
A 25 MHz TCXO with FOX24B-25 and 74LVC1G86 as a buffer giving 15 dBm, all at 3.3V.
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Hi the voltage that switch the LNB is 15 V. The typical voltage to provide is 18 V.
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before the patch was running.
after the patch the ready led is not light.