Still have this 2995DXCF on the desk. After getting the volume issue resolved, I checked everything out on my equipment. I noticed it swings backwards regardless of power level setting.
At a 45w deadkey, it swings backwards down to around 18w in average mode on the meter.
At 5w deadkey it doesn't move, unless you talk louder, then it backs up to 4.5w in average.
Talked to a guy in Ireland yesterday and he said it has a strong carrier but low in modulation.
In peak, it shows 135w peak, regardless of power level setting.
I did notice, where the limiters are normally cut or removed, this surface mount limiter (q48) is caddy cornered in it's place, I think they call this "defeating the limiter".
The gate voltage on the driver and final are between 3.8v at 10ma on the driver and 4v at 100ma on the final.
The voltages on the passthrough show correct in AM mode, 14v on emitter, 13.9v on base and 4.5v on collector.
Touching red probe of voltmeter to mirror board in AM shows 4.5v.
Checked power supply output, right at 13.9v and does not drop at all when keyed up with modulation.
VCO buffers maxed out as per service manual.
Using a stock cobra (coffin style) handmic. Works great on every radio I work on, has great sound quality also.
Why so much backward swing in average?
I looked on the small mode switch button for any surface mount diodes as another user on here had found was their issue, but there are no diodes at all on that board, just wires, connectors and a jumper.
No mods of any kind that I can tell other than frequency conversion for 11m and limiter defeated. Although I did find a could smashed apart back in the lpf section, I straightened it back out like it should be, still backwards swing.
Sideband and AM both swing right at 135w peak.
Any suggestions guys?
Thinking about doing the C258 jump with a 100 ohm resistor and 1n4001 diode to see if I can get the average to swing forward at all. I know I may have to remove R301 for this to work. I'm guessing the 10uf 25v cap in that same R301 array is the AMC timing cap. Would like to change that out for a 4.7uf 25v for better overall average power but it's surface mount and must be soldered on top and bottom, I'm not that equipped yet, lol...
At a 45w deadkey, it swings backwards down to around 18w in average mode on the meter.
At 5w deadkey it doesn't move, unless you talk louder, then it backs up to 4.5w in average.
Talked to a guy in Ireland yesterday and he said it has a strong carrier but low in modulation.
In peak, it shows 135w peak, regardless of power level setting.
I did notice, where the limiters are normally cut or removed, this surface mount limiter (q48) is caddy cornered in it's place, I think they call this "defeating the limiter".
The gate voltage on the driver and final are between 3.8v at 10ma on the driver and 4v at 100ma on the final.
The voltages on the passthrough show correct in AM mode, 14v on emitter, 13.9v on base and 4.5v on collector.
Touching red probe of voltmeter to mirror board in AM shows 4.5v.
Checked power supply output, right at 13.9v and does not drop at all when keyed up with modulation.
VCO buffers maxed out as per service manual.
Using a stock cobra (coffin style) handmic. Works great on every radio I work on, has great sound quality also.
Why so much backward swing in average?
I looked on the small mode switch button for any surface mount diodes as another user on here had found was their issue, but there are no diodes at all on that board, just wires, connectors and a jumper.
No mods of any kind that I can tell other than frequency conversion for 11m and limiter defeated. Although I did find a could smashed apart back in the lpf section, I straightened it back out like it should be, still backwards swing.
Sideband and AM both swing right at 135w peak.
Any suggestions guys?
Thinking about doing the C258 jump with a 100 ohm resistor and 1n4001 diode to see if I can get the average to swing forward at all. I know I may have to remove R301 for this to work. I'm guessing the 10uf 25v cap in that same R301 array is the AMC timing cap. Would like to change that out for a 4.7uf 25v for better overall average power but it's surface mount and must be soldered on top and bottom, I'm not that equipped yet, lol...
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