The Lafayette HA460 6M AM transmitter used a 6CW4 Nuvistor as a preamp. Mine survived a lightning strike to my 6M beam, which melted the Gamma Match and destroyed the front end harmonics filter. All tube, expect for a set of DC inverter transistors that allowed for mobile operation. Relatively good RF sensitivity for an AM rig of the era.
Gingerly repaired it served me many years in the late 1960's and still sits in the shack. Sporatic-E was strong in those days, to the extent you could easily DX low channel TV channels cross country. I turn it on every few months for 10-15 minutes in an attempt to keep the electrolytic capacitors polarized.
JKCalhoun 4 hours ago [-]
"Valves" had always been a mystery to me. When I began to really get into electronics, vacuum tubes were a kind of distant echo from my childhood that I barely remembered. As a kid I remember staring into the back of the small B&W television we had when I was young — the insides looking to me like some kind of Things to Come cityscape in miniature — all lit with orange neon. And there too was the ubiquitous "tube tester" in the Rexall Drug Store (looking somewhat like a prop from perhaps Lost in Space).
As an adult Thomas J. Lindsay’s books on building small regenerative vacuum tube receivers caught my attention — I also got caught up in building both tube-based guitar amplifiers and hi-fi audio amplifiers. These allowed me to dive into tubes and finally learn about them — you know, posthumously as it were.
After initially thinking that tubes were probably inferior in all ways to solid-state, I came to find them to still be very capable and even arguably better — at least with regard to sound amplification. Somehow too I had imagined in my mind they were outrageously dangerous to work with — thousands of volts — and assume,ed they were fragile and quick to "burn out".
The circuit I used however never went over 300 or so volts (to be sure, you still need to be careful with these circuits in a way you may not be familiar with if Arduino circuits are all you know).
The tubes have never seemed to burn out for me — even after one or two amps have been my "daily drivers" for well over a decade (two decades?) now. Perhaps other circuits used less capable tubes or pushed them to their limits? Perhaps other enclosures like TV's did not allow adequate ventilation? I don't know.
And as for fragility — I mean they are glass, but the tubes I used in my hi-fi amps were NOS from WWII bomber radios. They seem to hold up to a good deal of bouncing around.
analog31 3 hours ago [-]
There's a chance that in the heyday of tube electronics (mostly TVs), tubes were being stressed to within an inch of their life for cost reduction.
I'm a musician, an an electronics expert, though I don't use a tube amp myself. There's a lot of chatter on web forums about replacing tubes and capacitors, suggesting that it's done much more often than necessary. Someone's amp will get crackly, so the first thing they'll try is new tubes. Then capacitors. Finally the flaky pot or connector that's the actual root cause.
i_am_proteus 3 hours ago [-]
Guitar amps that routinely blow tubes usually operate past maximum rated plate voltage. As an example, the Fender Twin Reverb[0] runs 6L6GCs[1] at 460V plate voltage, above the stated class-AB pentode max of 450V.
I've used the same tubes at a very reasonable 325V in a SET (actually single-ended pentode) hifi amp (built myself).
TV tubes would often burn out because of transients from switching channels.
Tubes burn out a lot less than most people think. I’ve got working tubes that are 60 years old and in active use. I have a tube tester and they do fail, but not ever 1-2 years like some think is a needed replacement cycle.
ycui1986 32 minutes ago [-]
tube’s failure is such that if they survive the infant fatality, they will be more robust and reliable than transistor. The transmitters on Voyager probes have been going for 47 years. Those tube were pre-screened ones that survived from infant fatality. It’s like sea turtle, if they survive first few years in the wild, they will a very long lifespan.
fuzzfactor 39 minutes ago [-]
I put my electronics lab in mothballs over 10 years ago but up until the end my main audio scope was an HP from the 1970's that was all solid-state, except for the Nuvistor on each channel's input.
ringeryless 4 hours ago [-]
could this be used in a guitar amplifier circuit?
that is one of the few domains where valve technology still holds a superior position, in terms of product lines
JKCalhoun 4 hours ago [-]
I expect so. Pull up a spec sheet for the Nuvistor in question and see if meets the needs. Triode or pentode ... there are guitar amps and topologies for either. Depending on their specs, they might not work in the power amp stage of a guitar amp but perhaps the pre-amp — so you could get a hybrid.
drfoku 4 hours ago [-]
I’d like to see a solar-powered computer composed primarily of nuvistors and other nuclear hardened parts. Maybe it could survive nuclear holocaust and be an oracle for some future tribe.
throwanem 1 hours ago [-]
I'd like to see a pig with a CF6 under each wing. Does it matter?
cwmoore 1 hours ago [-]
If it’s AI does it matter? I’d like to see analog woowoo verified too.
Any fool knows a dog needs a home.
throwanem 48 minutes ago [-]
AI doesn't see and isn't seeing. Why? Did you have in mind some doghouse?
Rendered at 16:59:21 GMT+0000 (Coordinated Universal Time) with Vercel.
Gingerly repaired it served me many years in the late 1960's and still sits in the shack. Sporatic-E was strong in those days, to the extent you could easily DX low channel TV channels cross country. I turn it on every few months for 10-15 minutes in an attempt to keep the electrolytic capacitors polarized.
As an adult Thomas J. Lindsay’s books on building small regenerative vacuum tube receivers caught my attention — I also got caught up in building both tube-based guitar amplifiers and hi-fi audio amplifiers. These allowed me to dive into tubes and finally learn about them — you know, posthumously as it were.
After initially thinking that tubes were probably inferior in all ways to solid-state, I came to find them to still be very capable and even arguably better — at least with regard to sound amplification. Somehow too I had imagined in my mind they were outrageously dangerous to work with — thousands of volts — and assume,ed they were fragile and quick to "burn out".
The circuit I used however never went over 300 or so volts (to be sure, you still need to be careful with these circuits in a way you may not be familiar with if Arduino circuits are all you know).
The tubes have never seemed to burn out for me — even after one or two amps have been my "daily drivers" for well over a decade (two decades?) now. Perhaps other circuits used less capable tubes or pushed them to their limits? Perhaps other enclosures like TV's did not allow adequate ventilation? I don't know.
And as for fragility — I mean they are glass, but the tubes I used in my hi-fi amps were NOS from WWII bomber radios. They seem to hold up to a good deal of bouncing around.
I'm a musician, an an electronics expert, though I don't use a tube amp myself. There's a lot of chatter on web forums about replacing tubes and capacitors, suggesting that it's done much more often than necessary. Someone's amp will get crackly, so the first thing they'll try is new tubes. Then capacitors. Finally the flaky pot or connector that's the actual root cause.
I've used the same tubes at a very reasonable 325V in a SET (actually single-ended pentode) hifi amp (built myself).
TV tubes would often burn out because of transients from switching channels.
[0]https://schematicheaven.net/fenderamps/twin_reverb_ab763_sch...
[1]https://frank.pocnet.net/sheets/127/6/6L6GC.pdf
that is one of the few domains where valve technology still holds a superior position, in terms of product lines
Any fool knows a dog needs a home.