Posts by YO9HZN


    Isn’t dangerous for the transceiver to use a power protector as a load? Maybe something like pull-up tx-inhibit pin on IC-910 when the LNB is powered would be safer.

    For best performance i modified today sample rate of rtl_sdr to 300000 and now i can see perfect the beacons. 1MHz would be too mouch for RPi to handle regarding the 8 clients that i set the max users.

    In my case i have center_freq=739675000 and shown_center_freq=10489675000.

    Also posted online on for about two weeks now

    73! de YO9HZN!

    Just establish what is the center frequency coresponding for the center frequency of IF (in your case 1129), then modify that into the line of config file that says shown_center_freq=

    Originaly the value is “center_freq” so you need to write 10489.xxxx instead of that.


    After confirmation from Connor Winfield that it is an original, and the only difference between D75F 027.0 MHz and D75F 025.0 MHz is... 2MHz (HI), I did some new tests today and manage to keep the oscillator drift as low as posible, monitoring the 56 harmonic on 1,4GHz . First of all changed the capacitor between output and ground from 12pF to 15pF, insert another capacitor 10nF straight between D75F pins ground and +3,3V (allready have one on 1117 LDO) . "Bandaged" tcxo with kapton tape and insert-it inside small copper enclosure grounded with F connector as output. I am satisfied for now with the result. No more "chirp" present, no more sudden drift. Measured until now, about 500Hz in 4 hours.

    L.E. That is total drift, with rtl-sdr v3 (1ppm TXCO) tuned to 956MHz

    73 DE YO9HZN!

    Sorry for delayed answer. The LNB is a Octagon OTLSO model 1609. I use one of the F connectors to feed the RT320M chip with 25MHz from shack (for the more stable temperature and future use of a GPSDO). Forgot to eliminate the capacitors at the quartz pins. Will try today to measure the 56-th harmonic of D75F 25.000 , and compare-it with other TCXO less stable, with sdr# and a rtl-sdr stick with external 28.8MHz reference from Rohde&Schwarz generator.

    I tryed with 3.3V (measured 3.27V) pin from RPI 3 B, then Arduino Uno 3.3V pin. Same voltage, same result. Today I used a 117 linear LDO with 0.1uF decoupling caps (3.38V) . On pad 5 12pF to ground. Searched for optimal level using a CATV Amplifier (revers channels part of it , 5-50 MHz)... same results. Now I use the LNB with a TXC 25.000MHz 535NC 0041 txco. Works great , but it drifts +/- 5kHz at the 10706 beacon, dependent with the room temperature. Mail sent to ConWin. Waiting for the answer.

    73 Adrian , YO9HZN

    dg0opk I hope my post didn't offend you in any way. I never said that my source of information was your article about LNB mods. Just trying to find out why there is so much difference between TXCO from same series but not the same frequency.

    DD0KP I hope is not the case because i bought it from digi-key, part number CW654CT-ND Connor-Winfield #D75F-025.0M , paid 14.49$ + taxes...

    My intention is to help other hams not to spend money and (most important) time trying to use D75F 25MHz TCXO, like the one in the picture from my last post, with RT320M. It could be a both-side problem , TCXO+LNB, not figure-it out by now. I will try to send a e-mail to ConnorWinfield to get the whole picture.....

    73 de YO9HZN

    Hello! Very disappointed on my LNB mod with tcxo D75F 25.000. The beacon stays within +/-3khz around 10706.000, but frifts at every second, making the signal to chirp,not usable :( . Never drifts more than 2khz away even when wormed with solder iron, but the way it compensating it’s making it useless. I don’t understand why this happens, because i got to order D75F after reading about succesful results with 27MHz LNB’s