Skip to main content

A temproary diversion from the Antenna installation --- Homebrew Crystal Filters

A Diversion from the Antenna Installation

 
My life seems to be consumed with installing the new two element beam; but it appears that the goal of having an new antenna may take a bit longer than thought (or desired). There has to be a workable solution that does not involve spending $3000 on a small tower. I have received some new inputs that will require a bit more noodling so the antenna project is now in the "needing more evaluation" stage.
 
So we don't lose your interest in this blog I want to share some tribal knowledge about building homebrew crystal filters. There is much information about the actual selection and characterization of homebrew filters and I will not cover that aspect. My bent is once you have the filter crystals and the selected capacitors how do you translate that into hardware.
 
In a recent project of mine called the LBS - II, I decided to use a 5.185 MHz homebrew crystal filter principally because I misplaced my normal stash of 4.9152 MHz crystals which happens to be my most favorite IF frequency behind 9.0 MHz. Because the LBS - II was (by design) to utilize Surface Mount parts to make the radio more compact I needed a way to install the crystals in a small footprint. Some noodle time came up with a layout that works and in fact is ideal if one elects to use the 9.0 MHz SSB Filter Kit Model #351 sold by INRAD. Here are the specifics:
 
  • The footprint involves five pad areas of 0.2 inches wide by 0.4 inches long. Thus the overall size is 1 inch long by 0.4 inches wide.
  • All of the filter capacitors are soldered along one edge of the assembly (this makes adjustments very easy to accomplish).
  • The design provides a good ground plane area under the crystals which is very important to achieve the stop band attenuation
  • The board can be made by etching, milling or ugly style with a hacksaw and xacto knife
  • The board area being small is ideal for retrofitting into existing designs
  • An all important final step is to connect all of the crystal cans to ground which is another factor in the stop band attenuation.

Drum Roll Please

Layout for the 9.0 MHz INRAD Crystal Filter


The 5.185 MHz  filter installed on the LBS-II. The Ground Wires have not been added at this point.

 
Stay Tuned de N6QW
 

Popular posts from this blog

2019 ~ What is the simplest homebrew SSB Transceiver that can be built?

4/27/2019 The Future of our Hobby is Here! Forget those simple rigs with homebrew crystal filters, cranky IRF510's and the analog VFO's. SDR is the wave that is building strength just like a Tsunami. With the Soft Rock V6.3 SMD Version + RRPi2 With the Omnia SDR and RPi2 Pete N6QW How Simple & How Cheap can you  build a Homebrew SSB Transceiver? 4/26/2019 --- I just converted my websites from an obsolete Windows Based Server with GoDaddy to their cPanel (Linux). This was a cost issue as a one year renewal of the Windows Server would buy three years on the cPanel. GoDaddy is discouraging the use of what they call the Obsolete Windows System. So I had to migrate and reload the whole pastapete.com, jessystems.com and the n6qw.com sites to the Linux based servers. Some files and links got lost in the translation --so you might not be able to see everything! Essentially I have  to open every link to verify that it works --that may take some time

New Technology for 2020 ~ The Hermes Lite 2.0 SDR Transceiver

  The Hermes Lite 2.0 SDR Transceiver. November 7th, 2020 ~ It's Settled! It is done! The stain of the Trump era is soon to be removed! Thanks to all who voted. The Voice of the People has been heard.  Congratulations to President Elect Biden and Vice President Elect Harris. Pete N6QW November 3rd, 2020 -- IT WAS THE MOUSE   We all know this is Dump Trump  Day. Go out and vote! It was the mouse! Back in 1999 I stupidly was one of the very first to purchase a Ten Tec Pegasus. Never buy the first batch of a new model.  Touted as the world's first computer controlled radio , actually I think the Kachina 505 was really the first. But the Pegasus was fraught with problems including a trip back to the Smokey Mountains. I was using an older Windows 95 machine to control the Pegasus and that may be a co-conspirator. Well after many calls to TT -- finally someone who has some smarts told me: Fix your station ground, Make all leads short and Buy stock in a ferrite bead company. I did all

The Next Project Updated 10/10/2022! The rubber has hit the pavement!

The Next Project... A 2022 Transceiver. 10/10/2022 My Apologies. It is with regret that I will be terminating any further work on this project. My caregiver duties have over time become a greater time sink and it is almost impossible to build something working only 10-15 minutes at a time spread out over a day. I apologize for not getting it from design ideas to complete hardware. Most likely I have built the last transceiver I will ever build. Thanks for riding along. My website https://www.n6qw.com/  has the pdf of the postings and I will leave this blog page as is. 73's Pete N6QW 10/05/2022 Still Alive! Regrettably my caregiver duties have overtaken any free time so not much progress. But I am hopeful yet this week I will cut at least one board. A PSA from N6QW.  Think of it like Mary Jo has a "crink" in her back and unable to get in the backseat of the 57 VW Beetle. A bit of a setback but not forever.  Seems like the hired caregiver had a small emergency and not able