w8cbc
12-05-2005, 03:33 PM
My first HF transmitter, it was landed on me with all relevant documentation by a friend when I upgraded to General in July. It hadn't been turned on in years and he didn't know its history so I looked upon it as a Project.
Well, it fired right up. There were just a few minor details to sort out before I could pop it on the air.
Frequency coverage: 3500-4000kc, 7000-7425kc, 14000-14350kc, 21000-21525kc, 28000-29700kc
Modes: CW, plate-modulated AM. SSB with an adaptor which I don't have but may build.
Output: Up to about 120 watts carrier if I push the finals.
Finals: Two 6146s in parallel.
Modulators: Two 6CA7s in push-pull.
Stability: It's solid in 80 metres after warm-up, rather drifty in 40 metres, very drifty in 20 and shorter. I've some work to do in the VFO before I can do CW in the shorter bands.
Audio quality: I've been told it sounds "very nice" in AM.
CW operation: Sweet and smooth.
Antenna matching: Specced for 20 to 600 ohms, it loads up the zigzag in 40 metres and shorter no problem. I use the homebuilt T network in 80.
Mechanical: Heavy and solid but the linkages are a little cranky and the plate loading/tuning control bands have a bit of backlash. I've tried tightening them to no avail. Not a serious problem. VFO tuning is precise.
Spectral purity: Some weak harmonics. I haven't done a precise lab-bench analysis on it but they're well down. The finals will oscillate key-up in 80 if I'm not careful with the match so neutralisation obviously needs adjustment. I'll have to find or build a dip meter to take care of this.
Overall: A nice rig with potential to be much better if I had the ambition to work on it some more. Unfortunately, my back is shot - the result of having had more enthusiasm than brains when I was 19 - and hauling the Apache out to the dining room table for diagnosis and adjustment is a major chore.
For now, the Apache does CW and AM in 80 and 40 metres with the R392 (separate review) serving as the receive side. The two together make for a comfortable setup. I do plan to figure out what's up with the VFO and stabilise it for the shorter wavelengths.
Well, it fired right up. There were just a few minor details to sort out before I could pop it on the air.
Frequency coverage: 3500-4000kc, 7000-7425kc, 14000-14350kc, 21000-21525kc, 28000-29700kc
Modes: CW, plate-modulated AM. SSB with an adaptor which I don't have but may build.
Output: Up to about 120 watts carrier if I push the finals.
Finals: Two 6146s in parallel.
Modulators: Two 6CA7s in push-pull.
Stability: It's solid in 80 metres after warm-up, rather drifty in 40 metres, very drifty in 20 and shorter. I've some work to do in the VFO before I can do CW in the shorter bands.
Audio quality: I've been told it sounds "very nice" in AM.
CW operation: Sweet and smooth.
Antenna matching: Specced for 20 to 600 ohms, it loads up the zigzag in 40 metres and shorter no problem. I use the homebuilt T network in 80.
Mechanical: Heavy and solid but the linkages are a little cranky and the plate loading/tuning control bands have a bit of backlash. I've tried tightening them to no avail. Not a serious problem. VFO tuning is precise.
Spectral purity: Some weak harmonics. I haven't done a precise lab-bench analysis on it but they're well down. The finals will oscillate key-up in 80 if I'm not careful with the match so neutralisation obviously needs adjustment. I'll have to find or build a dip meter to take care of this.
Overall: A nice rig with potential to be much better if I had the ambition to work on it some more. Unfortunately, my back is shot - the result of having had more enthusiasm than brains when I was 19 - and hauling the Apache out to the dining room table for diagnosis and adjustment is a major chore.
For now, the Apache does CW and AM in 80 and 40 metres with the R392 (separate review) serving as the receive side. The two together make for a comfortable setup. I do plan to figure out what's up with the VFO and stabilise it for the shorter wavelengths.