Need advice 1x 25Mhz bias, 3x10Mhz

Remi PD0RBO · Apr 13th 2019

Hi all,

First things first, all I know is learned by myself by reading and trial and error. So if you see something obvious please do mention.

My goal is to design a simpele and low cost (>=€50,-) 25Mhz reference with bias-t and 3x 10Mhz sin out.

The valeus of the parts in the schematic need to be revised/calculated and I have to note that they are indicative only.

Question #1

As writing software is not my strong point, I’m looking for a solution to “fix” the settings in the neo-7M module. Right now I planned a Attiny45 on the PCB and hope to find someone that can help me out with the software. Writing software in the uC is no problem as I have done that numerous times. Writing software myself, well I can make a LED blink but thats it.

So if any can make suggestion?

Question #2

Can someone revise my schematic, confirm it is correct or if not make suggestions?

Any additional suggestions are welcome.

Thnx in advance

20190413-schematic.pdf

20190413-pcb.pdf

DD0KP · Apr 13th 2019

Remi PD0RBO pd0rbo if you have a neo7 module with an eeprom you can store the settings there I think without any uC beside. This could be done with the UBLOX SW from the internet. If you need some code for your ATtiny I can write this for you. Your schematics looks ok..

Remi PD0RBO · Apr 13th 2019

Quote from DD0KP

Remi PD0RBO pd0rbo if you have a neo7 module with an eeprom you can store the settings there I think without any uC beside. This could be done with the UBLOX SW from the internet. If you need some code for your ATtiny I can write this for you. Your schematics looks ok..

Thanks

The Ublox module stores the settings only when backup battery is supplying the memory, when discharged the settings are gone.

If you think it is no trouble for you to help me out there, that would be great.

The thoughts/reservations I have are I can get +10-15dB of the FH1-g, do I need one or two for reference to the LNB? And can I set the GPS module to 100KHz and get rif of 2x 74HC390 without haring to worry about much jitter?

DD0KP · Apr 13th 2019

I must have a closer look in detail..will response later Remi...

do1ctl · Apr 13th 2019

DD0KP

Hello Heiner,

can you help me with the sketch for Arduino Mini to set the ADF4351 with two different frequencies.

I did not find anything suitable on the internet for me.

I already have the contents of the registers.

73 de Frank

DD0KP · Apr 13th 2019

do1ctl Frank drop me an email call@darc,de

DD0KP · Apr 13th 2019

or you can look look here:

https://www.sv1afn.com/adf4351m.html

do1ctl · Apr 13th 2019

Quote from DD0KP

do1ctl Frank drop me an email call@darc,de

done

Remi PD0RBO · Apr 13th 2019

Quote from DD0KP

I must have a closer look in detail..will response later Remi...

I will look forward to it 👍

Progress until now, by the looks of it there’s room to spare.

i2NDT · Apr 14th 2019

do1ctl DD0KP

another approach is to use a PIC to program up to 8 (or 1 or 4...) different frequencies selected by a deep switch:

https://wiki.batc.org.uk/ADF435x_PIC

i2NDT Claudio

Remi PD0RBO · Apr 14th 2019

Quote from i2NDT

do1ctl DD0KP

another approach is to use a PIC to program up to 8 (or 1 or 4...) different frequencies selected by a deep switch:

https://wiki.batc.org.uk/ADF435x_PIC

i2NDT Claudio

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Thank you Claudio!

This makes my day and inspires me to implement optional up&downconversion on my board.

SM7PNV · Apr 22nd 2019

For code to program the Neo GPS, this could be suitable : https://github.com/HarrydeBug/1009-GPS_Derived_RF_Generator

It is written for Arduino and ATMega328 but could be adaptable to the ATTiny.
On the other hand if you want it to be super easy - you could change from ATTiny to ATMEGA328 so you can use the code directly.
It will only increase your BOM cost with a euro or two but make it radically faster as the code already does exactly want you want to do (set the GPS timing output to a fixed output frequency at each startup)

73

//Harry

Remi PD0RBO · Apr 23rd 2019

Good point Harry!

I have a Nano on hand and wil experiment with your GitHub suggestion

Thanks

Need advice 1x 25Mhz bias, 3x10Mhz

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