w8cbc
12-05-2005, 05:25 AM
This is the ultimate in tough old tube gear, literally and figuratively bullet-proof. I've had mine for almost 10 years and it's dug out the signals like nothing else I'd ever used until I got "modern" and picked up an ICOM IC-751A (see separate review).
Anyway.
Readout: Mechanical digital.
Accuracy: hash marks every 200 Hz, digits every 1kc. Internal calibrator at every 100 kc. Should be used if retuning more than 200kc.
Frequency stability: Less than 200 Hz drift after 15 minutes warm-up.
Coverage: Tunes DC to 32020kc, actually receives 470-32020kc. It's specced to perform above 500kc. So, no longwave without preselector modification.
Modes: AM, CW/SSB. The (tunable) BFO is a bit weak, RF gain has to be backed off to make strong SSB signals intelligible. This could be due to a weak BFO tube; I'm short on spares.
Power: 28 volts DC at 5 amps.
Tubes: 6AJ5 (5) sharp-cutoff pentodes various RF/IF
12AU7A (5) med-mu twin triodes various misc
26A6 (11) remote-cutoff pentodes RF/IF amplifiers
26A7GT (1) twin power pentode audio output
26C6 (2) twin diode + triode 1st and 2nd mixers
26D6 (1) pentagrid converter VFO/3rd mixer
Sensitivity: Uneven, depending upon the MHz setting. Alignment is very picky. Still, it's not the least bit deaf - if a signal is above atmospheric noise, the R392 will dig it out.
Selectivity: Three bandwidths - 2, 4, and 8kc. The 8kc setting is too broad for anything but mediumwave AM broadcast; the 4kc setting is a bit narrow for SWBC listening. The 2kc setting is for the tough cases and it separates them out quite nicely. Skirts at 4 and 2kc are steep. Not so at 8kc.
Dynamic range: Incredible. Volts of RF won't overload the thing. You'll roast the preselector coils first (and I have - leaky T/R switch, oops - they were a bit of a job to repair).
Audio quality: A bit thin, though it could be due to the speaker I'm using.
Limiter: Harsh. It'll get rid of any impulse noise thrown at it. It'll also get rid of much of the signal's modulation. Use in severe circumstances.
Mechanical: Tough. It was designed to go through a war. Everything is solid and heavy-duty. You won't break this radio by dropping it. If it lands on your foot though, you'll break your foot. Tubes are held in their sockets by locked, spring-loaded shields - they won't work their way out. Tuning mechanism is complex, gear-and-cam-driven, and very smooth.
Extra goodies: 455kc IF takeoff on the front, useful for a scope display or external detector for FM or whatever else might be desired. AGC switch which shorts the input in "CAL" (useful while transmitting). A relay-operated squelch that's sensitive and crisp. Spring-loaded carry handles - essential!
Operation: Simple and straightforward. You need to exert some strength to change the MHz range - a good wrist builder. With 25 vacuum tubes in it, the thing gets warm. Rather pleasant in a cool environment.
The thing is great for SWL/DX and very good for CW. It's a bit rough with SSB because of the weak BFO (see above). The vacuum tubes in it are mostly rather difficult to find and a fresh set is essential for maximum performance.
I use the R392 now in conjunction with an Apache for the "real radio" side of my station. The two go together very nicely.
Anyway.
Readout: Mechanical digital.
Accuracy: hash marks every 200 Hz, digits every 1kc. Internal calibrator at every 100 kc. Should be used if retuning more than 200kc.
Frequency stability: Less than 200 Hz drift after 15 minutes warm-up.
Coverage: Tunes DC to 32020kc, actually receives 470-32020kc. It's specced to perform above 500kc. So, no longwave without preselector modification.
Modes: AM, CW/SSB. The (tunable) BFO is a bit weak, RF gain has to be backed off to make strong SSB signals intelligible. This could be due to a weak BFO tube; I'm short on spares.
Power: 28 volts DC at 5 amps.
Tubes: 6AJ5 (5) sharp-cutoff pentodes various RF/IF
12AU7A (5) med-mu twin triodes various misc
26A6 (11) remote-cutoff pentodes RF/IF amplifiers
26A7GT (1) twin power pentode audio output
26C6 (2) twin diode + triode 1st and 2nd mixers
26D6 (1) pentagrid converter VFO/3rd mixer
Sensitivity: Uneven, depending upon the MHz setting. Alignment is very picky. Still, it's not the least bit deaf - if a signal is above atmospheric noise, the R392 will dig it out.
Selectivity: Three bandwidths - 2, 4, and 8kc. The 8kc setting is too broad for anything but mediumwave AM broadcast; the 4kc setting is a bit narrow for SWBC listening. The 2kc setting is for the tough cases and it separates them out quite nicely. Skirts at 4 and 2kc are steep. Not so at 8kc.
Dynamic range: Incredible. Volts of RF won't overload the thing. You'll roast the preselector coils first (and I have - leaky T/R switch, oops - they were a bit of a job to repair).
Audio quality: A bit thin, though it could be due to the speaker I'm using.
Limiter: Harsh. It'll get rid of any impulse noise thrown at it. It'll also get rid of much of the signal's modulation. Use in severe circumstances.
Mechanical: Tough. It was designed to go through a war. Everything is solid and heavy-duty. You won't break this radio by dropping it. If it lands on your foot though, you'll break your foot. Tubes are held in their sockets by locked, spring-loaded shields - they won't work their way out. Tuning mechanism is complex, gear-and-cam-driven, and very smooth.
Extra goodies: 455kc IF takeoff on the front, useful for a scope display or external detector for FM or whatever else might be desired. AGC switch which shorts the input in "CAL" (useful while transmitting). A relay-operated squelch that's sensitive and crisp. Spring-loaded carry handles - essential!
Operation: Simple and straightforward. You need to exert some strength to change the MHz range - a good wrist builder. With 25 vacuum tubes in it, the thing gets warm. Rather pleasant in a cool environment.
The thing is great for SWL/DX and very good for CW. It's a bit rough with SSB because of the weak BFO (see above). The vacuum tubes in it are mostly rather difficult to find and a fresh set is essential for maximum performance.
I use the R392 now in conjunction with an Apache for the "real radio" side of my station. The two go together very nicely.