Thank you for all your work testing and selecting the values to make the amp work well with newer radios. I just finished restoring a SB-200 that had been in storage for about 18 years. It works well but as you have shown the input circuits leave a lot to be desired. I have tried tuning the input slugs but they are all firmly stuck in position. Did you have to work to release you slugs? What method did you use to loosen them? I also went through your first video several times to gleam information that helped me with my amplifier. 73 Ken WA1BFS
What was your method to adjust the input circuit? I have an SB 200 and it runs great on 80, 40, and 20 but 15 and 10 not so well. So what is the process to trouble shoot? KN6YKE
You need a pure 50 ohm source of a minimum of 10W and adjust the input components for a minimum SWR on the input to the amp for each band. At the same time you must peak the output of the amp for maximum into a pure 50 ohm dummy load as the output tuning of the amp reflects changes to the input. It becomes a balancing act between the output and input until you get it right.
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Thanks for all the info. I'm having some issues in the SWR input for the upper bands and this will help me figure something out
Good information. Thank you.
Thank you for all your work testing and selecting the values to make the amp work well with newer radios. I just finished restoring a SB-200 that had been in storage for about 18 years. It works well but as you have shown the input circuits leave a lot to be desired. I have tried tuning the input slugs but they are all firmly stuck in position. Did you have to work to release you slugs? What method did you use to loosen them? I also went through your first video several times to gleam information that helped me with my amplifier. 73 Ken WA1BFS
Your tuning slugs may be waxed in place. A heat gun may help to get them out.
What was your method to adjust the input circuit? I have an SB 200 and it runs great on 80, 40, and 20 but 15 and 10 not so well. So what is the process to trouble shoot? KN6YKE
You need a pure 50 ohm source of a minimum of 10W and adjust the input components for a minimum SWR on the input to the amp for each band. At the same time you must peak the output of the amp for maximum into a pure 50 ohm dummy load as the output tuning of the amp reflects changes to the input. It becomes a balancing act between the output and input until you get it right.