18-01-2022, 09:45 PM
Hi all,
A little bit more progress tonight, 1 minute key down to see what gets hot.
Replaced the unknown blue coax balun that got hot with with RG400. That gets mildly warm now.
Added a 10pf ATC100B across input to balun ( I saw this on other designs and wondered what effect it might have, it increased the gain ) I experimented with other values either side of 10pF but that value is optimal.
Output power is now 56.6dBm aka 457w @ 50v and 12.5A so that computes to 73% efficiency
Additional 1 minute key down to see what else gets hot and found that the 12.5ohm coax used for the impedance transformer gets quite warm, so I'll replace that with something beefier.
The 1.3mm wire in the LPF isn't going to cut it either, they get too hot to touch so I'll upgrade those to 2mm enameled wire.
cheers
Tim
A little bit more progress tonight, 1 minute key down to see what gets hot.
Replaced the unknown blue coax balun that got hot with with RG400. That gets mildly warm now.
Added a 10pf ATC100B across input to balun ( I saw this on other designs and wondered what effect it might have, it increased the gain ) I experimented with other values either side of 10pF but that value is optimal.
Output power is now 56.6dBm aka 457w @ 50v and 12.5A so that computes to 73% efficiency
Additional 1 minute key down to see what else gets hot and found that the 12.5ohm coax used for the impedance transformer gets quite warm, so I'll replace that with something beefier.
The 1.3mm wire in the LPF isn't going to cut it either, they get too hot to touch so I'll upgrade those to 2mm enameled wire.
cheers
Tim