Carlson Violated A Cardinal Rule

[bd139]

Worth noting that respectable folk appeal to both the newbies and the professionals. It's an art to present to both but you have to if you want to be credible and retain viewers.

In context Carlson puts up a newbie friendly view but does things and uses explanations which are incomplete and tries sell completeness as a side product. Also he does stupid shit quite often.

IMSAI Guy has no idea what the hell he is doing at all and it's just his conscious mind leaking into YT.

Curious Marc has a lot of spare time to waste on not thinking before doing something and then lots of backtracking and unnecessary work takes place.

Dave wows people with things but leaves explanations and entire repairs incomplete almost on every video.

There is room for better.

[mnementh]

Shahriar/TSP does well at eliminating wasted minutes, but his material and presentation style assumes a certain minimum level of engineering knowledge, and is not very noob/normie friendly, as he does not have time to explain the basics of a P-N junction, etc. I do, however, appreciate that he has enough of a sense of humor to also have the secondary channel, TNP.

The other thing I do appreciate is that he very clearly understands what he's working on, has read the manual, and knows how to use it and how it's SUPPOSED TO work.

Dave could learn a lot from him; both in style and core philosophy. So many times I've seen him just go off on something he has on the bench and the entire problem is simple failure to RTFM.

mnem

[tggzzz]

Shahriar/TSP does well at eliminating wasted minutes, but his material and presentation style assumes a certain minimum level of engineering knowledge, and is not very noob/normie friendly, as he does not have time to explain the basics of a P-N junction, etc.

Cannot - and should not attempt to - do everything. It is better to do one thing well than two things poorly.

The other thing I do appreciate is that he very clearly understands what he's working on, has read the manual, and knows how to use it and how it's SUPPOSED TO work.

That was started by Jerry Pournelle (may he rot in hell), in his grossly lazy Byte column.

Dave could learn a lot from him; both in style and core philosophy. So many times I've seen him just go off on something he has on the bench and the entire problem is simple failure to RTFM.

Dave does have some explanatory videos.

Quite, but even that wouldn't give most people A Clue

[Zenith]

Worth noting that respectable folk appeal to both the newbies and the professionals. It's an art to present to both but you have to if you want to be credible and retain viewers.

I don't believe you can present to both and satisfy both audiences. You have to pick your intended audience and pitch appropriately. For newbie things, which might appeal to people who've covered it before but a long time ago, you have to present it in a digestible way - not littered with unnecessary equations - and don't commit any excessive short cuts or howlers. Some topics may not have a large audience, even among "professionals" - how you managed to replace an unobtainable hybrid in some 1980s HP equipment, with a cleverly worked out substitute using modern parts.

I can't say I watch any of the electronics Youtubers religiously. I have recently acquired an HP8601A sweeper and I watched IMSAI Guy's two videos on that. I thought they were somewhat disappointing, especially the second, but on balance worth watching. Some of his later stuff has been a bit chaotic, such as how he managed to destroy a MAX038. I tend to watch these things late at night when I'm having trouble dropping off to sleep. They do have to dream up new things to present.

I think that to succeed, they have to entertain and inform enough people, and Carlson, Dave Jones, IMSAI Guy, w2aew and others, manage to do that.

[AVGresponding]

Worth noting that respectable folk appeal to both the newbies and the professionals. It's an art to present to both but you have to if you want to be credible and retain viewers.

In context Carlson puts up a newbie friendly view but does things and uses explanations which are incomplete and tries sell completeness as a side product. Also he does stupid shit quite often.

IMSAI Guy has no idea what the hell he is doing at all and it's just his conscious mind leaking into YT.

Curious Marc has a lot of spare time to waste on not thinking before doing something and then lots of backtracking and unnecessary work takes place.

Dave wows people with things but leaves explanations and entire repairs incomplete almost on every video.

There is room for better.

Ian Scott Johnston does it very well imo.

12voltvids can be frustrating; he has a lot of specialised knowledge, but his "stream of consciousness" style can be tedious and his occasional rough as arseholes methods and tools can be quite distracting.

[AVGresponding]

Worth noting that respectable folk appeal to both the newbies and the professionals. It's an art to present to both but you have to if you want to be credible and retain viewers.

I don't believe you can present to both and satisfy both audiences. You have to pick your intended audience and pitch appropriately. For newbie things, which might appeal to people who've covered it before but a long time ago, you have to present it in a digestible way - not littered with unnecessary equations - and don't commit any excessive short cuts or howlers. Some topics may not have a large audience, even among "professionals" - how you managed to replace an unobtainable hybrid in some 1980s HP equipment, with a cleverly worked out substitute using modern parts.

I can't say I watch any of the electronics Youtubers religiously. I have recently acquired an HP8601A sweeper and I watched IMSAI Guy's two videos on that. I thought they were somewhat disappointing, especially the second, but on balance worth watching. Some of his later stuff has been a bit chaotic, such as how he managed to destroy a MAX038. I tend to watch these things late at night when I'm having trouble dropping off to sleep. They do have to dream up new things to present.

I think that to succeed, they have to entertain and inform enough people, and Carlson, Dave Jones, IMSAI Guy, w2aew and others, manage to do that.

Marco Reps does the best mix of inform and entertain, for me, at least when he's actually doing a repair and not shilling something.

[mnementh]

Ian Scott Johnston does it very well imo...

Ooooh muhh loooord... 'tis lahhk list-en-inn' tuh Scotty talk abooot hackin' yooor tesst geeer!!!

mnem

[AVGresponding]

Ian Scott Johnston does it very well imo...

Ooooh muhh loooord... 'tis lahhk list-en-inn' tuh Scotty talk abooot hackin' yooor tesst geeer!!!

mnem

His presentation style isn't the easiest to deal with, but his analysis technique is en pointe

[tautech]

Dropped in on a DJ livestream blah blah yesterday and after 10 min decided there were better things to do with my life.
Defpom's last weekend was much better with dudes like xdevs and IanSJ there for a good while,

[BU508A]

There is room for better.

Shahriar from The Signal Path for example.
And FeedBackLoop is imho also okay.

[vk6zgo]

I like Alan W2AEW's videos.
They are like having a very knowledgeable friend invite you into his Ham Shack/Lab & tell you a lot of interesting stuff.
Jose Gavila, EB5AGV doesn't do videos, but his website is a very enjoyable read for geeks.

As an old Greybeard, some things Carlson says about tube equipment grate a bit!
Of course, it isn't just him, & is "sort of" justifiable.
Many of the tubes available today were "pulled" years ago for heater cathode leakage, hence the mania for DC heaters.
It isn't the whole answer, though, as if the leakage is relatively high, you are swapping hum insertion for bias problems.

Shango066 craps me to tears!

[25 CPS]

One of the things that Mr. Carlson said in a few videos I've watched that bothers me is that it's ok to have no load on tube amplifiers in radios etc. and the output transformer will be fine as long as you don't have the volume turned up.

This is true, if everything goes fine, but all it's going to take is accidentally introducing a too hot signal, some noisy faulty component that got missed, some amplifier instability, something like that happening by accident to drive the amplifier to significant output and possibly damage the transformer. Can you be absolutely 100% guaranteed certain that nothing like that will happen? Clipping on a dummy load in place of a speaker that's been disconnected is cheap insurance so why take unnecessary chances?

[Zenith]

That's not a great idea because it's very easy for an output transformer with no load to generate high voltages. Some equipment is notoriously liable to damage in this way, such as the CR88/AR88. In that case the output transformer is very easily damaged by being run with no load. If the speaker leads slip off it dies very quickly. Also it's a special transformer with a feedback tap so it can't be properly replaced by a transformer from a domestic radio. Spares are nearly unobtainable these days.

As you say, why risk it when it's easy to use a suitable resistor. I'm surprised that Carlson suggested that.

[mansaxel]

I like Alan W2AEW's videos.
They are like having a very knowledgeable friend invite you into his Ham Shack/Lab & tell you a lot of interesting stuff.

Seconded. He's taught me a lot.

[MED6753]

That's not a great idea because it's very easy for an output transformer with no load to generate high voltages. Some equipment is notoriously liable to damage in this way, such as the CR88/AR88. In that case the output transformer is very easily damaged by being run with no load. If the speaker leads slip off it dies very quickly. Also it's a special transformer with a feedback tap so it can't be properly replaced by a transformer from a domestic radio. Spares are nearly unobtainable these days.

As you say, why risk it when it's easy to use a suitable resistor. I'm surprised that Carlson suggested that.

Early germanium transistor amplifiers were subject to same potential to fry if run with no load or an improper load.

[vk6zgo]

That's not a great idea because it's very easy for an output transformer with no load to generate high voltages. Some equipment is notoriously liable to damage in this way, such as the CR88/AR88. In that case the output transformer is very easily damaged by being run with no load. If the speaker leads slip off it dies very quickly. Also it's a special transformer with a feedback tap so it can't be properly replaced by a transformer from a domestic radio. Spares are nearly unobtainable these days.

As you say, why risk it when it's easy to use a suitable resistor. I'm surprised that Carlson suggested that.

Most output transformers of the classic tube era were "tough as old boots", so you could pretty much get away with it.
I remember one time my rather bodgy connections to a "free range" (no enclosure) 12" speaker fell off, seeing nice big "car CD ignition style" sparks zapping across the pins of the output tube of a "Mullard 3-3".

I was worried, but there was no sign of damage.
That was a serious Hi-Fi transformer with a lot of copper & iron in it, so it's "Q" as a high voltage producer would have been much higher than the usual domestic "mantel set" of the 1950s.

The default breakdown of mantel set output transformers seemed to be shorted turns in the primary, with the speaker & secondary still intact.
Speakers died from time to time without killing output transformers.

It seems that the AR88/CR88 was more an exception from the general rule, but these days, with "speaker transformers" mostly languishing deep in landfill worldwide, instead of being on the shelves of every electronics shop, it is probably better to err on the side of caution.

[Zenith]

Yes but in the 70s and 80s domestic valve radios were being thrown out. The transformers were then 20 to 30 years old. The tone correction capacitor was typically rated at 1000 volts and absorbed some of the volts if the speaker was disconnected. Now they are are 60 to 70 years old, and they haven't improved with age. Replacements are not that cheap or easy to find.

Some valve hi-fi amplifiers have transformers which are prone to failure with age. There are replacements - at a price - and some of those have problems, such as high frequency resonances.

The point is why risk it, when a moment's carelessness which causes mains hum to be picked up, can cause disaster?

[vk6zgo]

Yes but in the 70s and 80s domestic valve radios were being thrown out. The transformers were then 20 to 30 years old. The tone correction capacitor was typically rated at 1000 volts and absorbed some of the volts if the speaker was disconnected. Now they are are 60 to 70 years old, and they haven't improved with age. Replacements are not that cheap or easy to find.

Some valve hi-fi amplifiers have transformers which are prone to failure with age. There are replacements - at a price - and some of those have problems, such as high frequency resonances.

The point is why risk it, when a moment's carelessness which causes mains hum to be picked up, can cause disaster?

Your last point is pretty much what I said in the last sentence of my post.

Thinking about it, though, plain old domestic radio transformers are probably candidates for rewinding in the home workshop.
I doubt if they used any fancy winding schemes, the main difference between them & power transformers is probably core material. (Indeed, small power transformers have been used as output transformers in non-critical applications with varying measures of success.)

Hi Fi output transformers are a "different kettle of fish"!

[bd139]

Interesting about the domestic radio transformers. During the early to late 80s I was forever hawking for old valve radios being discarded because the transformers were easy to rewind, or at least unwind. I couldn't afford batteries so the mains was the place to get your juice from for early transistor experiments. Unfortunately 6v was a little too low and 150-200v or so was more than a little too high. 15-25v was about right. Didn't need a lot of current so the winding would take it fine. So the trick was to carefully unpick the HT secondary and unthread it until you got the volts you needed. Due to the not too high price of copper at the time, the wire was thick enough to be able to do this without breaking it so it'd get unwound a few turns carefully, then measured via a rectifier and smoothing cap until it was about the right voltage.

Typically those transformers are pretty expensive now and the transistor ones are the ones in the trash! I dread to think how many I mutilated!

[Zenith]

A difference between radio output transformers and mains transformers is that the o/p transformers always carry DC, so they had a gap in the core, usually a piece of paper. So while they were more or less interchangeable, there was a difference. Removing windings from a radio o/p transformer seems like a lot of hassle.

I find I have an occasional need for mains transformers to produce 6 to 24V RMS no load, for replacements in various things I come across, e.g. the Ballantine 323. If you have to buy them new they are surprisingly expensive. I watch out for bits of junk, such as ancient and useless modems, at rallies. They are worth a couple of quid for the transformer, possibly the case, and other bits and pieces. Discarded burglar alarms are also worth looking out for, although I haven't seen one for a time.

Another candidate for a mains power supply based on a transformer of that sort, is a battery only HP427A I picked up. It needs 16 to 22.3V DC, but it only draws a few mA. A possible approach is a voltage doubling rectifier. That's one for the winter when there's nothing much else to do.

[bd139]

I have a mains / rechargeable HP 427A in my possession that the battery died in (well melted). Got it from Robert at a hamfest. I replaced the battery and charger with a simple battery eliminator circuit (LM317) and used the existing transformer. Worth noting that the transformer on the mains variety is actually in a well shielded container in the bottom of the meter so the magnetic field doesn't futz with anything else.

They are very nice little meters.

[Zenith]

Interesting.

In this one it was a 22.5V dry battery, an Ever-Ready 637??. I believe you can still get substitutes at a price. Because the current draw is so low, a couple of PP3s would do at a pinch. There was no mains option. Rechargeable for that era implies what was once a NiCd battery, but is now a grotty mass of hazardous waste, which has corroded various other parts. If you are lucky, some sensible soul removed it years ago, before it leaked and caused damage.

I could just use a wall wart to avoid magnetic fields inside the instrument. Some of those are AC.

A previous owner had codged it with red and black sockets on the back, with 22.5 Volts written between them with a marker pen. The battery connectors were soldered to the sockets. The battery regulator may have been damaged by over voltage or reversed polarity.

My impression of it is that it's an interesting piece of classic HP gear. In the 60s, a portable Valve Voltmeter (equivalent - it uses a FET) must have been quite something. These days, not so much so. I've seen £40 asked for them at swapmeets, but I wouldn't like to think I'd paid anything like that for one.

I sorted out the problem with the battery regulator and put contact cleaner on the wafer switches. Then I saw it had a few other problems. The ohms function doesn't do anything. The DC reversed range is pretty accurate but the normal DC range reads about a third of what it should. Odd, because as far as I can see, the difference between the two is that the meter connections are reversed.

There are lawns to be mowed and hedges to be cut, so I put it back together to wait for a dark winter day.

[tggzzz]

I had a Tek 1502 with a buggered transformer and battery.

I removed the transformer, inserted an AC->12V converter, and connected that to the battery terminals.

Perfect, except you couldn't use it in a field in these conditions...

[bd139]

Interesting.

In this one it was a 22.5V dry battery, an Ever-Ready 637??. I believe you can still get substitutes at a price. Because the current draw is so low, a couple of PP3s would do at a pinch. There was no mains option. Rechargeable for that era implies what was once a NiCd battery, but is now a grotty mass of hazardous waste, which has corroded various other parts. If you are lucky, some sensible soul removed it years ago, before it leaked and caused damage.

I could just use a wall wart to avoid magnetic fields inside the instrument. Some of those are AC.

A previous owner had codged it with red and black sockets on the back, with 22.5 Volts written between them with a marker pen. The battery connectors were soldered to the sockets. The battery regulator may have been damaged by over voltage or reversed polarity.

My impression of it is that it's an interesting piece of classic HP gear. In the 60s, a portable Valve Voltmeter (equivalent - it uses a FET) must have been quite something. These days, not so much so. I've seen £40 asked for them at swapmeets, but I wouldn't like to think I'd paid anything like that for one.

I sorted out the problem with the battery regulator and put contact cleaner on the wafer switches. Then I saw it had a few other problems. The ohms function doesn't do anything. The DC reversed range is pretty accurate but the normal DC range reads about a third of what it should. Odd, because as far as I can see, the difference between the two is that the meter connections are reversed.

There are lawns to be mowed and hedges to be cut, so I put it back together to wait for a dark winter day.

The ohms failing happened to mine as well. Check the electrolytic capacitors. They go short. That and some crusty trimpots and the dead NiCd was all that was wrong with mine.

They are a very nice design actually. The FET input leakage is compensated using a temperature compensated diode to reinject the leakage current back in. That gives it a "stupid high" input impedance.

I paid £10 for mine so a good deal

[Zenith]

The ohms failing happened to mine as well. Check the electrolytic capacitors. They go short. That and some crusty trimpots and the dead NiCd was all that was wrong with mine.

They are a very nice design actually. The FET input leakage is compensated using a temperature compensated diode to reinject the leakage current back in. That gives it a "stupid high" input impedance.

I paid £10 for mine so a good deal

Worth remembering as that sort of tip can avoid a lot of messing about.

Offhand I remember the manual saying that the input impedance was 10MegOhms, but it's not a point I'd defend vigorously.

I paid £10 for mine, in a moment of weakness. I'd always been curious about them and that's the main reason I bought it. I'm not suffering from major purchaser remorse, but I've had better value for a tenner or less on several occasions. It's small and light which is an advantage. There'll be several hours of innocent amusement in sorting out its problems. I'm not noted for my enthusiasm for cleaning things, but it's very satisfying when you take some of this TE which is in a grotty state, with mould, grime and stickers, dose it with kitchen cleaner and maybe IPA, rinse it off and dry it, and it's transformed.