1206 Attenuator PCB

wip_d2

This page is work in progress and may be updated frequently (last update : 2020-04-10 15:37 UTC). 

This is a updated design of the previous 1206 Attenuator PCB (aka a failure in PCB design).

Introduction

As a hamradio homebrewer I often use attenuators to get a signal down a few dB and sometimes I want very strange values. For those cases I designed these 1206 PI network Attenuator PCB's with SMA Edge connectors using KiCad. 

1206_att_sch

Based on this schematic I designed the PCB shown below. I added area's without solder mask around the edges to a low adding some shielding over the PCB (not visible in image below).

1206_att_pcbv2

The cool thing from KiCad is that is also has a 3D viewer. Unfortunately the SMA Edge connectors aren't in the 3D shape library.

1206_att_3dv2

For the attenuation values I used this calculator : https://chemandy.com/calculators/matching-pi-attenuator-calculator.htm and  the image below contains a list of "standard" PI network attenuation resistor values. 

1206_att_tbl

It's nice to have it all in theory but we want the real thing. So I ordered small batch of pototype PCB's to see if I didn't mess up this simple design. 

 

Let's test them/

When the "small" batch of PCBs came in (ok, I orded a little more then I needed, but like to fill up my webshop ;-) 

1206_att_02

1206_att_03

I couldn't resist building 2. One  0dB and one 10dB.

1206_att_01

and put them to the test using my NanoVNA H4 (to later find out that i configured 1.2GHz instead of 1.5GHz). :-S 

Test setup : NanoVNA H4 with 2 x 20cm test leads, frequency span 1MHz to 1.2GHz.

0dB Attenuator PCB @ 600MHz.

1206_att_m01

10dB Attenuator PCB @ 600MHz.

1206_att_m02

10dB Attenuator PCB @ 1179MHz 

1206_att_m03

 

Test setup : NanoVNA H4 with 2 x 20cm test leads, frequency span 1MHz to 450MHz.

0dB Attenuator PCB @ 225MHz 

1206_att_m04

0dB Attenuator PCB @ 450MHz 

1206_att_m05

10dB Attenuator PCB @ 225MHz 

1206_att_m07

 10dB Attenuator PCB @ 450MHz 

1206_att_m06

Conclusion : 

Much better the the previous version and one for the keeping for atleast up to 1.2GHz. 

 

Where to buy 

From the not so small batch of PCBs I have a "few" left, these will be put on sale on this For-Sale page.
 

The design will be publicly available in the near future so you order your own PCB's at OSHPark but licensed it Attribution-NonCommercial-NoDerivs 3.0 Unported (CC BY-NC-ND 3.0).
Meaning : 

  • Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
  • NonCommercial — You may not use the material for commercial purposes.
  • NoDerivatives — If you remix, transform, or build upon the material, you may not distribute the modified material.

It's not to be childish but it now happened a few times that a  designs I made was sold by other people just because is was "Open source, so I can do anything I want with it" without any credits or even a token of appreciation

When you like the design and PCB's. a small fee as a token of appreciation / commission to support my work is very appreciated (see : Support & Tip Jar).

 


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