We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations. Always consult with the appropriate authorities if you have questions concerning what is permissible in your locale.

« previous next »
Pages: [1]

Author Topic: 22 meter low pass filter design  (Read 1976 times)

Offline N9QIW

  • Jr. Member
  • **
  • Posts: 41
    • Winfield, IN USA
    • View Profile
    • Email
22 meter low pass filter design
« on: December 05, 2020, 0433 UTC »
Does anyone have a design schematic for a 13.56 mhz a simple low-pass filter? I can always look at the various online calculators,  but just curious if anyone has a schematic that they like to use/has proven history.  Thanks in advance.   I'm in the process of building/programming/testing a 22 meter WSPR transmitter.
Logged
Alex
N9QIW
Winfield, IN

Offline ThaDood

  • DX Legend
  • ******
  • Posts: 1384
    • Likely, not where you are.
    • View Profile
    • Extreme Part #15!
    • Email
Re: 22 meter low pass filter design
« Reply #1 on: December 05, 2020, 0715 UTC »
Well, yeah!!!! Just copy the one that I made for this 13.560MHz milliwatt TX,     http://boomerthedog.net/13560.html   Scroll down to the bottom for the two page .PDF schematic, then check-out the Chebychev Filter that's at the end of Q3, and between TP3 and TP4, on the LPF Board. All built from salvaged parts as well. Good luck!!!
Logged
“I am often asked how radio works. Well, you see, wire telegraphy
is like a very long cat. You yank his tail in New York and he
meows in Los Angeles. Do you understand this? Now, radio is
exactly the same, except that there is no cat.”
-Attributed to Albert Einstein, but I ripped it from the latest Splatter .PDF March 2025 issue.

Offline NJQA

  • Sr. Member
  • ****
  • Posts: 344
    • Virginia
    • View Profile
Re: 22 meter low pass filter design
« Reply #2 on: December 05, 2020, 1445 UTC »
I would think that any 20 meter LPF kit would work.  There are a number of them designed for QRP from places like qrp-labs.com and qrpkits.com that are very inexpensive.  I would expect that the second harmonic from 22 meters would be as well supressed as would that from 20 meter signal.
Logged

Offline N9QIW

  • Jr. Member
  • **
  • Posts: 41
    • Winfield, IN USA
    • View Profile
    • Email
Re: 22 meter low pass filter design
« Reply #3 on: December 06, 2020, 0626 UTC »
Thanks ThaDood and NJQA for the advice.  I absolutely enjoyed reading the hand-drawn schematic you made ThaDood-lots of work involved and good job getting the thought process down on paper.  NJQA- Great minds think alike.  The 20m LPF crossed my mind as well.   Both of you thanks again for your advice and input. 
Logged
Alex
N9QIW
Winfield, IN

Offline Stretchyman

  • Hero Member
  • *****
  • Posts: 664
    • View Profile
Re: 22 meter low pass filter design
« Reply #4 on: December 07, 2020, 2213 UTC »
https://rf-tools.com/lc-filter/

Simples..

I'd get used to LSPICE too..

Str.
Logged
'It's better to give than receive' so why Rx when you can Tx!

                                              ;)
Pages: [1]
« previous next »
 

HFUnderground Mug
HFUnderground Mug
by MitchellTimeDesigns