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TNT 400 variable capacitors function
- Thread starter Cuervo
- Start date
They are part of the output tuning. I'm not certified to give a better explanation.
IMO each 2 pill section should be tuned independently before they are combined and a fixed value capacitor installed. That way everything is balanced. That may have been done at one time but as soon as someone gets happy with the screwdriver all bets are off. The trimmer caps are ok but people can't leave them alone.
Your swr issue sounds like oscillation and could be because the amp isn't tuned properly.
IMO each 2 pill section should be tuned independently before they are combined and a fixed value capacitor installed. That way everything is balanced. That may have been done at one time but as soon as someone gets happy with the screwdriver all bets are off. The trimmer caps are ok but people can't leave them alone.
Your swr issue sounds like oscillation and could be because the amp isn't tuned properly.
High SWR at low carrier level, but falls of with a higher drive level.
Perfectly-normal behavior for a Class-C amplifier.
A linear with fixed bias should not do this.
The 'trombone' capacitor is the impedance matching for the output. It's set for maximum peak power, then soldered down.
Not convenient to "tweak". Shouldn't need to until major components get changed.
73
Perfectly-normal behavior for a Class-C amplifier.
A linear with fixed bias should not do this.
The 'trombone' capacitor is the impedance matching for the output. It's set for maximum peak power, then soldered down.
Not convenient to "tweak". Shouldn't need to until major components get changed.
73
Whups!
Off on a tangent. Wrong post. Wrong forum.
No trombone in this amp. Except maybe for the one playing "Wha-wha-wha-whaaaaa" with the mute over the end bell.
The mica-compression trimmer caps in this 25-plus year old amplifier are indeed peaked for max modulated power.
Right function, wrong page.
73
Off on a tangent. Wrong post. Wrong forum.
No trombone in this amp. Except maybe for the one playing "Wha-wha-wha-whaaaaa" with the mute over the end bell.
The mica-compression trimmer caps in this 25-plus year old amplifier are indeed peaked for max modulated power.
Right function, wrong page.
73