DIY SMA 50 ohm RF Attenuators

Make your own SMA fixed attenuators that perform decently from 50 Khz to 1.2/1.3 Ghz.
Below are the resistors ordered from DigiKey. Be sure to order extra as they easily get lost!
Use 2 same value paralleled resistors for RA and R1/R2 (See schematic and chart in video).
Use a tiny spec of instant glue to hold them together.
1/2W SMD resistors are easier to work with than 1/8W while using tweezers to set them in place.
DigiKey Part # Description Reference
P143AACT-ND 143 OHM 1% 1/2W 1210 10 dB - RA
RMCF1210FT191 191 OHM 1% 1/2W 1210 10 dB - R1/R2
RMCF1210FT121 121 OHM 1% 1/2W 1210 20 dB - R1/R2
RMCF1210FT499RCT-ND 499 OHM 1% 1/2W 1210 20 dB - RA
541-590AACT-ND 590 OHM 1% 1/2W 1210 3 dB - R1/R2
RMCF1210FT34R8CT-ND 34.8 OHM 1% 1/2W 1210 3 dB - RA
541-301AACT-ND 301 OHM 1% 1/2W 1210 6 dB - R1/R2
RMCF1210FT75R0CT-ND 75 OHM 1% 1/2W 1210 6 dB - RA

[@lmantuano6986]

Great stuff! but can you please tell us what value resistors and their combinations (if in parallel or series) to get the correct/approx values? Basically how close the the values in the table one needs to get to? Also what wattage rating resistors? Thanx...

[@rfburns3472]

Thank you for your comment!
Yes, I will add to the description the information you requested and the resistor values and order numbers from DigiKey hopefully this week.

[@lmantuano6986]

@@rfburns3472 Brilliant! thank you very much for the details and your dedication! 73 de vk3OLA

[@rfburns3472]

@@lmantuano6986 Your absolutely welcome OM! Please let me know how it works out for you.

[@IZ0MTW]

Nice video. Very good results up to a certain freq for these DIY attenuators. There are a few chinese ones out there and most likely are the same but you saved money and have the possibility of customize the attenuation value to your needs. About the HP attenuator, don’t forget to account for the two BNC to SMA adapters, especially if they’re not good quality.If you calibrate the vna WITH those using a double female BNC I believe you should get better results out of the HP.
Best wishes
Diego

[@rfburns3472]

@@IZ0MTW Thank you Diego! Yes, the connectors can be a real concern especially at those VHF/SHF frequencies.