02-01-2022, 02:34 PM
Tim
Phewww ! (Wipes sweat from forehead..)
The 0.2dB figure is a heap better but will still be interested to (eventually) hear how hot your LPF inductors are immediately after RF is removed after running at/near full power.
When you get to measuring actual amp output 2F and 3F product levels with the SA, set your 2M reference level then add a series 2M L-C notch circuit across the output of the power sampler/coupler (use a BNC or N Tee with a short cable length to the notch) to attenuate the base signal level before you look at the 2F and 3F levels.
Otherwise the SA is likely to be in signal overload from the 2M fundamental, particularly if you change the SA input attenuator settings, and your readings will be largely invalid.
I use a shaft-control air-variable C and a few turns of tinned copper wire in a small diecase box and my notch covers from about 105 to 190 MHz.
After setting the reference level, simply add the notch and watch the 144MHz signal component as you tune for a minimum. Usually about a 20-25dB drop depending on construction.
The LC notch will be largely 'invisible' to 2F and 3F products.
Keep up the good work
Doug
Phewww ! (Wipes sweat from forehead..)
The 0.2dB figure is a heap better but will still be interested to (eventually) hear how hot your LPF inductors are immediately after RF is removed after running at/near full power.
When you get to measuring actual amp output 2F and 3F product levels with the SA, set your 2M reference level then add a series 2M L-C notch circuit across the output of the power sampler/coupler (use a BNC or N Tee with a short cable length to the notch) to attenuate the base signal level before you look at the 2F and 3F levels.
Otherwise the SA is likely to be in signal overload from the 2M fundamental, particularly if you change the SA input attenuator settings, and your readings will be largely invalid.
I use a shaft-control air-variable C and a few turns of tinned copper wire in a small diecase box and my notch covers from about 105 to 190 MHz.
After setting the reference level, simply add the notch and watch the 144MHz signal component as you tune for a minimum. Usually about a 20-25dB drop depending on construction.
The LC notch will be largely 'invisible' to 2F and 3F products.
Keep up the good work
Doug
Doug VK4ADC @ QG62LG51
http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.
http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.