Low Cost PCB's Low Cost Components

Author Topic: RTL-SDR TCXO Upgrade  (Read 438 times)

0 Members and 2 Guests are viewing this topic.

Offline bjcuizon

  • Frequent Contributor
  • **
  • Posts: 262
  • Country: nz
  • RF and Analog Electronics Enthusiast
RTL-SDR TCXO Upgrade
« on: October 13, 2017, 10:23:31 AM »
Hi, I watched the video of the guy at analogzoo.com about making a 28.8MHz tcxo for the sdr dongle and I'm thinking about building something similar. http://www.analogzoo.com/2016/03/building-a-better-rtl-sdr-tcxo/
He basically uses a 19.2MHz 10ppm Crystal where he divides its frequency by two then filters out the third harmonic going out of the divide-by-two chip which is 28.8MHz. He also uses a normal variable capacitor and a negative temp coefficient cap both in parallel with the xtal.
My question is that can I just desolder the original, un-temp compensated 28.8MHz crystal from the sdr and just add the two variable caps in parallel?

*By the way my sdr dongle is the same as his.

Thanks :)

Schematic Pic
« Last Edit: October 13, 2017, 01:28:32 PM by bjcuizon »
Don't mess with an Electronics Engineer, it Megahertz!
 

Offline Ebel0410

  • Newbie
  • Posts: 2
  • Country: fr
Re: RTL-SDR TCXO Upgrade
« Reply #1 on: October 14, 2017, 05:51:16 AM »
Hi bjcuizon

imho, your best bet will be to buy a dongle which is already powered with a TCXO or CXO clock.
Modifying a RTL dongle is really tricky, smd are really small,  and I think this is not the best solution.
I bought a Nooelec NESDR Smart, not expensive, and I'am very satisfied with its clock performance (miles away from low priced dongles with a simple 28.8M crystal)
Save your time and money, buy another dongle.

(I bought a better piece of hardware last month, a SDRPLAY RS2, 12 bits DAC resolution,  very impressive)
Regards
Eric
 
The following users thanked this post: bjcuizon

Offline medical-nerd

  • Regular Contributor
  • *
  • Posts: 100
  • Country: gb
  • What's that coming over the hill?
Re: RTL-SDR TCXO Upgrade
« Reply #2 on: October 14, 2017, 09:35:14 PM »
Hiya

There are 28.800MHz DIP oscillator modules and 14.400Mhz DIP TXCO modules (which can be passed through a frequency doubler) available on ebay. The signal can then passed through a filter made from the original crystal.
I aim to try both methods over the next few weeks.

And yes - I already have 2 x V3 dongles and a Thumbnet N3, but want to tinker with the standard dongles I also have.  ;D

If you want a relatively cheap already converted dongle have a look at:

https://www.rtl-sdr.com/new-rtl-sdr-blog-units-now-available-in-store-hf-via-direct-sampling-software-switchable-bias-tee-less-noisespurs/

https://www.rtl-sdr.com/review-of-the-thumbnet-n3/



Cheers
« Last Edit: October 14, 2017, 11:25:44 PM by medical-nerd »
'better to burn out than fade away'
 

Online metrologist

  • Frequent Contributor
  • **
  • Posts: 791
  • Country: us
Re: RTL-SDR TCXO Upgrade
« Reply #3 on: October 14, 2017, 10:55:29 PM »
...
I bought a Nooelec NESDR Smart, not expensive, and I'am very satisfied with its clock performance (miles away from low priced dongles with a simple 28.8M crystal)
Save your time and money, buy another dongle.

(I bought a better piece of hardware last month, a SDRPLAY RS2, 12 bits DAC resolution,  very impressive)
Regards
Eric

Just bought the NESDR SMArt dongle. I have an older RTL.SDR with two antenna ports, goes down to 100 kHz. Just realized SDR# cannot connect to it on win10
 

Offline bjcuizon

  • Frequent Contributor
  • **
  • Posts: 262
  • Country: nz
  • RF and Analog Electronics Enthusiast
Re: RTL-SDR TCXO Upgrade
« Reply #4 on: October 16, 2017, 04:43:38 PM »
Hiya

There are 28.800MHz DIP oscillator modules and 14.400Mhz DIP TXCO modules (which can be passed through a frequency doubler) available on ebay. The signal can then passed through a filter made from the original crystal.
I aim to try both methods over the next few weeks.

Cheers

Thanks but the price for one 28.8MHz tcxo is more than a low cost dongle right?
Maybe I'll just buy another one with tcxo and so I can listen to atc and receive adsb at the same time  :D

...And if you are going to test both methods out, please let us know ;)
Don't mess with an Electronics Engineer, it Megahertz!
 

Offline bjcuizon

  • Frequent Contributor
  • **
  • Posts: 262
  • Country: nz
  • RF and Analog Electronics Enthusiast
Re: RTL-SDR TCXO Upgrade
« Reply #5 on: Today at 09:26:02 AM »
I just bought "that $20 silver dongle" from amazon aka RTL-SDR V3 with the TXCO (they guaranteed 1ppm stability) and other stuff as well. Its going to arrive next week. I guess it's better than buying the 28.8 Meg TXCO for the same price. >:D
@medical-nerd Have you tried the methods you said? I'm interested to know your findings. ;)
Thanks
Don't mess with an Electronics Engineer, it Megahertz!
 

Offline cdev

  • Super Contributor
  • ***
  • Posts: 2148
  • Country: aq
  • [Personal Text]
Re: RTL-SDR TCXO Upgrade
« Reply #6 on: Today at 09:51:29 AM »
They make good gifts for geeky friends.

But I would never spend more than a few bucks on one.

$7 is enough for a good dongle..

Maybe $20 for the rtlsdr blog version 3 that has all the improvements.. maybe - but only IF you don't already have one.



« Last Edit: Today at 03:08:13 PM by cdev »
"What the large print giveth, the small print taketh away."
 

Offline bjcuizon

  • Frequent Contributor
  • **
  • Posts: 262
  • Country: nz
  • RF and Analog Electronics Enthusiast
Re: RTL-SDR TCXO Upgrade
« Reply #7 on: Today at 12:59:26 PM »
They make good gifts for geeky friends.
I know, it really would.  :D

But I would never spend more than a few bucks on one. $20 for the rtlsdr blog version 3 that has all the improvements.. maybe - IF you don't already have one.
Yeah, V3 seems the best as they really thought about the customers and its applications.
I guess it will stay for long before V4 as most improvements are done in this version...And PCB space is getting smaller.
Have a look at this:

Don't mess with an Electronics Engineer, it Megahertz!
 

Online metrologist

  • Frequent Contributor
  • **
  • Posts: 791
  • Country: us
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf