My wife's family was displaced when she was a toddler thanks to Idi Amin and they remained stateless for about 6 years in a bureaucratic limbo, so "Living in a shoe box in the middle of the road" regularly makes an appearance in our family conversations. I don't think our 12yr old finds it particularly motivating 
I agree.
I blame the stresses of living beyond our means for the end of my first marriage - I'd like to blame her exclusively but have to accept that I was complicit in the enterprise - it takes two to tango.
I have always lived on the edge of my means for about 40 years as an adult.
The bank account was almost empty at the end of the month.
About 2 years ago I became out of work and couldn't find anything.
So have lived off money my father left me and sold a few bits and bob on ebay but not enough to call a living.
Its odd that when I hadnt money I lived on the edge but once I had money I was out of work !
Short-term buy: a "The Beast" at Trailhead Cafe.
Beast is just grilled chee and bacon sandwich. Trailhead Cafe is a small not-real-commercial hangout in a very commercial tourist town. Their landlord thinks he can get a better shop in there and has terminated their lease, they close this month. (The cleaners may work much of the winter to make-ready for an upscale retail shop.)
Beast is just grilled chee and bacon sandwich. Trailhead Cafe is a small not-real-commercial hangout in a very commercial tourist town. Their landlord thinks he can get a better shop in there and has terminated their lease, they close this month. (The cleaners may work much of the winter to make-ready for an upscale retail shop.)
> Nothing ever feels as good as getting new test equipment!
GOOD test equipment.
$45 SPL meter with C-scale, 'Digital Sound Level Meter, AP-882A'. Yes I under-paid. It basically works with annoying faults. The head rattles and spikes the reading if you twitch (I'll add goo). Even un-rattled the reading jumps from 82 to 91 for no apparent reason. I can not get a reading below 38dB which may be the 1/4" electret or a 16-bit ADC scaled to 130dB SPL(!!). The carry-case is lovely but the foam wind-screen won't fit unless mashed severely. There are two output sockets AC and DC. One I assume is audio and the other appears to be a rectified and logged level suitable for strip-chart recorder.
Overall a not-good feel.
I have a quite different $80 SPL meter/logger coming and want to see the difference.
Books-
Strategies for Selecting and Verifying Hearing Aid Fittings, Valente, Michael
Hearing Instrument Science & Fitting Practices (Second Edition), Robert E. Sandlin
Digital Hearing Aids, Schaub, Arthur
Hearing Aids, Harvey Dillon
Hearing Tests and Hearing Instruments, Leland A. Watson, Thomas Tolan
Sound System Engineering, Third Edition, Don Davis, Eugene Patronis
Handbook of Hearing Aid Amplification, Vol I & Vol. II, Sandlin, Robert E.
GOOD test equipment.
$45 SPL meter with C-scale, 'Digital Sound Level Meter, AP-882A'. Yes I under-paid. It basically works with annoying faults. The head rattles and spikes the reading if you twitch (I'll add goo). Even un-rattled the reading jumps from 82 to 91 for no apparent reason. I can not get a reading below 38dB which may be the 1/4" electret or a 16-bit ADC scaled to 130dB SPL(!!). The carry-case is lovely but the foam wind-screen won't fit unless mashed severely. There are two output sockets AC and DC. One I assume is audio and the other appears to be a rectified and logged level suitable for strip-chart recorder.
Overall a not-good feel.
I have a quite different $80 SPL meter/logger coming and want to see the difference.
Books-
Strategies for Selecting and Verifying Hearing Aid Fittings, Valente, Michael
Hearing Instrument Science & Fitting Practices (Second Edition), Robert E. Sandlin
Digital Hearing Aids, Schaub, Arthur
Hearing Aids, Harvey Dillon
Hearing Tests and Hearing Instruments, Leland A. Watson, Thomas Tolan
Sound System Engineering, Third Edition, Don Davis, Eugene Patronis
Handbook of Hearing Aid Amplification, Vol I & Vol. II, Sandlin, Robert E.
Hi PRR,
Okay, I can't disagree. But even getting an old piece of RCA gear is fun for those of us who like to restore old test gear. But stuff to use on the bench - absolutely. Nothing gets me as excited as getting a new piece of good test gear. My last one was a Keysight 34465A multimeter. A lovely instrument, but it has to boot (?). Too much going on under that hood.
You did get a nice group of books. Another thing I love to find. Sometimes the older, the better.
-Chris
Okay, I can't disagree. But even getting an old piece of RCA gear is fun for those of us who like to restore old test gear. But stuff to use on the bench - absolutely. Nothing gets me as excited as getting a new piece of good test gear. My last one was a Keysight 34465A multimeter. A lovely instrument, but it has to boot (?). Too much going on under that hood.
You did get a nice group of books. Another thing I love to find. Sometimes the older, the better.
-Chris
So I went to local flea market and bought this for $4, ripped it apart and found nice speaker, heatsink and transformer. Transformer was main reason for buying this type of audio systems, name of system was Durabrand 5.1 sp-690w. Heatsink is 9x14cm speaker says 50w 8ohm and transformer is 8x4.5x7cm how can I know how much power can this transformer handle. I will use it only for headphone amps so I know i wont stress him at all but Im curious how to calculate. In this system transformer was powering 7 lm1875t's. Transformer fuse is 250V/1.5A.
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Got it on Thursday, but I've been so busy I've only had time to turn it on & check it out briefly. Hoping to spend some quality time with it this weekend.
> Leader LBO-524 Oscilloscope
I had the 15MHz. Great 'scope but marginal power supply. When the wall got to 110VAC the DC supplies would sag, at different rates, and it didn't work good. (I didn't realize the voltage in my office was that low. In retrospect I should have used a 12VCT transformer for 6V/12V of boost. Translate to your values. And if your wall is solid 240V it may not be an issue.)
I had the 15MHz. Great 'scope but marginal power supply. When the wall got to 110VAC the DC supplies would sag, at different rates, and it didn't work good. (I didn't realize the voltage in my office was that low. In retrospect I should have used a 12VCT transformer for 6V/12V of boost. Translate to your values. And if your wall is solid 240V it may not be an issue.)
I just bought a solid state replacement for an 83 mercury vapor rectifier.
Does anyone have any of these # 83 tubes? I would love to buy a pair. They are used in my tube tester (Stark 9-66).
I gave the new one I had to someone who had a broken one in their tube tester. I figured no biggie, and it got him up and running.
-Chris
Does anyone have any of these # 83 tubes? I would love to buy a pair. They are used in my tube tester (Stark 9-66).
I gave the new one I had to someone who had a broken one in their tube tester. I figured no biggie, and it got him up and running.
-Chris
Hi,
I'm not sure what the effect of replacing the #83 with a solid state rectifier would be for the calibration when testing tubes under load. I need to make certain because I absolutely depend on my tester. I need it to be right and correct reading.
It's the not knowing, the uncertainty. I have ordered a replacement kit so I can see what they are doing. Tom y way of thinking, you would need to create a 15V drop across the tube when in forward conduction, and also add some resistance to absolutely recreate what is happening with the #83. I do know that normal high vacuum rectifiers can't be used in this position.
What if the meter is actually more accurate with straight rectifier diodes? It's the uncertainty that I can't have. Better? Worse? Who knows? I do know that they compensated for various common negative aspects. Knowing that means I have to find out and not guess.
So, to answer your question, if the replacement for the #83 does mimic it properly, I'm happy using the solid state replacement. I wonder what difference the lack of heater current will have? It may stabilize the voltages for differences in small signal tube heater current. That would be more annoying if the line adjust has to be corrected more often.
-Chris
I'm not sure what the effect of replacing the #83 with a solid state rectifier would be for the calibration when testing tubes under load. I need to make certain because I absolutely depend on my tester. I need it to be right and correct reading.
It's the not knowing, the uncertainty. I have ordered a replacement kit so I can see what they are doing. Tom y way of thinking, you would need to create a 15V drop across the tube when in forward conduction, and also add some resistance to absolutely recreate what is happening with the #83. I do know that normal high vacuum rectifiers can't be used in this position.
What if the meter is actually more accurate with straight rectifier diodes? It's the uncertainty that I can't have. Better? Worse? Who knows? I do know that they compensated for various common negative aspects. Knowing that means I have to find out and not guess.
So, to answer your question, if the replacement for the #83 does mimic it properly, I'm happy using the solid state replacement. I wonder what difference the lack of heater current will have? It may stabilize the voltages for differences in small signal tube heater current. That would be more annoying if the line adjust has to be corrected more often.
-Chris
Hi PRR,
Neat instrument. It's very interesting that they have three models that represent three different acceptable maximum readings. Unions take note?
Mercury, when cold, condenses into a pool inside a mercury rectifier. They usually want to give the tube 15 minutes to 1/2 hour in order to get that pool of mercury into it's gaseous state. Before this happens, the tube is just a vacuum rectifier and can be damaged by higher current draws. If the tube was sitting off it's normal attitude, the mercury may end up where it may take longer to change state. So that means the tube has to be fully warmed up longer before you begin to draw current through it. Of course, the portable tube tester experiences exactly that. It's position is constantly changed until it is set up and turned on.
I can see that instrument being necessary in an industrial setting where they use the large rectifiers and ignitrons (like a tube SCR) that actually do have a substantial pool of mercury inside them. You would want to exit if someone broke one of those!
Thanks for posting that.
-Chris
Edit: Somewhere around here I have a plastic bottle with most of an ounce of pure Mercury in it. It'll turn up some day.
Neat instrument. It's very interesting that they have three models that represent three different acceptable maximum readings. Unions take note?
Mercury, when cold, condenses into a pool inside a mercury rectifier. They usually want to give the tube 15 minutes to 1/2 hour in order to get that pool of mercury into it's gaseous state. Before this happens, the tube is just a vacuum rectifier and can be damaged by higher current draws. If the tube was sitting off it's normal attitude, the mercury may end up where it may take longer to change state. So that means the tube has to be fully warmed up longer before you begin to draw current through it. Of course, the portable tube tester experiences exactly that. It's position is constantly changed until it is set up and turned on.
I can see that instrument being necessary in an industrial setting where they use the large rectifiers and ignitrons (like a tube SCR) that actually do have a substantial pool of mercury inside them. You would want to exit if someone broke one of those!
Thanks for posting that.
-Chris
Edit: Somewhere around here I have a plastic bottle with most of an ounce of pure Mercury in it. It'll turn up some day.