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1A21 generator 24volt generator relay

dkamp

eMail NOT Working
Yep, thin PTFE would be great. I haven't been to a hamfest in quite a while, so my shelf is empty... they've already cancelled the Dayton Hamvention, and I wasn't planning on taking time off for it, but my guess is that some of the local spring hamfests may get cancelled, so I MAY take 'ya up on that.

I have some incredibly fine 60/40 left. I should get online and buy myself a hoard of stock of better-quality stuff, this silver is NOT gonna play well with the TenTec when I replace those front-end PIN diodes...

Here's the box... I'll get it to the USPS on Monday. Not sure how they're handling 'em nowdays, they may park it in a room for 3 days before touching it, which I totally understand, or mebbie they'll just dump it in the basket and roll it on... but it's on the way!
ship.jpg
 

Zephyr7

Registered
Yeah, I saw about hamvention. I was thinking of going again this year too, I’ve missed going since they moved to Xenia since my daughter was born within a week of the first year they’d moved. Oh well, next year.

No problem sending you some if you want, just pm me. Freebie too for the good of the stak :) Teflon tubing really is the best product to use for this application.

You should try some wax paper to aid release of the coil next time so that you don’t have to trim anything away. If you want to have a former stay in place, I’d get some Nomex sheet and use that for a professional coil.

BTW, I see a 6m QSL there. Nice :) I miss my 6m beak (an M2 6M7). I don’t have anywhere to mount it on my new house yet. I hope to have a tower up at some point to get above the trees here (probably means a 100-120 foot tower). My best DX on that band was actually on a stacked pair of M2 loops though, that were on a mil surplus portable mast with the top loop at about 33 feet up using a homemade RG11 matching harness. I got out to the Azores with that setup on my K3 with my new (at the time) KPA500. That was on sideband too and especially fun for me because I’ve always thought the Azores are a very interesting place.

Bill
 
Regarding solders.....


When I was making those Delco coils, I was running very low on my real, 60/40 American rosin core lead solder. I jumped on Epay and found solder....from China.....in small, affordable rolls so I ordered several. When heated, it seemed to flow "okay" but with a bit of effort. When it cooled the appearance was a dark gray color, which most of us know as a "cold" solder joint. It wasn't really, but the look bothered me so I went back to genuine rosin filled 'Murican solder. Looks like I'll be looking for some Kester somewhere...........
 

Zephyr7

Registered
There have been many reports of Chinese solder not working right.

You can buy Kester solder on amazon, techni-tool, probably digikey and mouser too. I personally really like the multicore brand solder (now a brand of loctite), but it’s expensive and harder to find.

I recommend not trying to save money on solder. Cheap solders tend to be unreliable. With a roll of solder usually lasting a REALLY long time, it’s best to just spend a little more to buy quality.

Bill
 

Kohlerallen

Registered
There we go. I had some brown scrap and two terminals. Unfortunately, this so-called 'electrical' solder is silver- rather than lead-based, and in most applications, it really sucks. Anyone else had that experience?

View attachment 385500

My apologies to any of you who happen to be stuck there...
Lead is a compound known to the state of California to cause Cancer.
California is a state known by the world to cause rampant stupidity.... (sigh).

Being outside in sunlight can cause cancer... so let's ban that, okay??
I'm impressed. That coil is looking good. With our present shelter in place situation I will have plenty of time to get it installed and do a test run.
 

dkamp

eMail NOT Working
I'm pretty certain the way USPS has been, that I can roll it out'a here on Monday, Allen- it'll be at your place in a day or two after, probably oughta hose it down good before cutting it open, but It will have been inside the bag and packaging for at least three days when you get it. Nobody sick here, btw.

Bill... I've got an M2 5el on 6m up right now, the tower is actually mounted on the west side addition roof, tiltover with winch in the attic lays it down in perfect maintnenace position on the garage roof- very handy. That beam puts it about 45 feet off the ground, which is in clear view of all horizons right now, but once there's leaves on the catulpa trees on the west edge of my property, it's a bit shrouded, but totally insignificant for E, F2, and tropospheric ducting. My prior house was right ON the river bank, I had a 86ft Rohn45 tiltover with 25ft of 3" mast on dual bearings, with a rather rare Telrex 6-element beam (what a beast!).

Most of those cards, believe it or not, were done using AM at 50.400, with a Comet GP15 vertical... and a Gonset G50 with the power supply modified- replaced the vacuum rectifier with a solid-state. The resultant change in voltage raised plate, and consequently output power by a fair chunk. My best DX on six though, was a ZL4 using split-mode... I was listening SSB on my Icom 551, and transmitting CW through the Heathkit Seneca... into the TELREX. When I heard it, I was pointed long-path... or better put... 'wrong path'... my strongest signal was bearing 353, which means it was bouncing off of something in a curve. He was running a quad 10 element EME kit with 1500w, so HIS end was clearly doing all the work. When I FIRST heard it, I was listening through the Gonset and vertical, RX was dialed down to 50.1ish... with it's wide front-end, I could hear activity, so went into spin-and-hunt mode, and there he was, working someone in Alaska... with a pileup forming up there. I started tapping out my (long back then) callsign, he heard it, and cleared a path through the pile for me. I banged out my answers in CW while hearing him clearly on SSB. Local DX'ers were all over the local repeaters telling me I was nutzo... and they did for another 5 minutes... 'till they saw the DX cluster explode. ;-D
 

Zephyr7

Registered
Guys, the OLD SCHOOL lead solder is STILL available in non-RoHS countries which includes the US! You don’t need to get old stuff, you can get new stuff from regular suppliers!

60/40 is the old lead/tin alloy. 63/37 is the “eutectic” solder, and many (including me) like it better. It is 63% tin and 37% lead.

The new lead-free solders will be labeled as “lead free” or “RoHS” or something like that. They are mostly tin with a little copper and silver thrown in along with a few other things. It’s really easy to tell them apart from the labeling.

Bill
 

dkamp

eMail NOT Working
So I'm feeling a combination of excitement and impatience to get Allen's measurements of AC, DC, and current readings... first, so I can compare the math and get an estimation of what the windings' survival time will be, and second, so I can get a really good concept of what they're being subjected to.

A relay is a gadget that has an electromagnet that pulls in contacts... but there's more. The coil is a conductor, which means current will pass through in either direction according to the limits identified in Ohm's Law with respect to resistance... that's where I calculated my 452 ohm result. But it's a coil of wire wrapped around a polepiece, which means it is also an inductor, which means it will pass in both directions, and in AC, up to a certain frequency, after which, it becomes more-or-less a 'brick wall'... because the magnetic field of that coil and polepiece is too dense to allow the current in the coil to change direction fast enough to allow current flow.

And here's where it gets interesting- An inductor can carry both AC and DC current at the SAME TIME. In this generator, the control system works on the principle that they're putting 24v across the plug, and sensing current flow through a light bulb. IIRC, it's a 40w minimum lamp required for it to 'sense' the presence of a load. With that load in place, a little bit of DC current flows through the lamp. Let's figure out how much current, at 24v, would flow through a 115v 40w lamp:

40w/115v = .347mA. That means the lamp's resistance must be 330 ohms.

If we apply 24vdc to a 330 ohm lamp, the current flowing is 0.073 amperes... 73mA.

In comparison, the 452 ohm coil winding, at 24v, would carry 53mA (and disspiating 1.27 watts)

Now, the coil winding would develop full magnetic draw at 53mA, applying 73mA means that the coil is at full capacity only two-thirds-of-the-way to the bulb's draw. This works out just fine, because they're not trying to 'illuminate' the lamp filament, they're just trying to determine wether it's THERE.

Now, once this generator starts, it's applying AC across that lamp, at the SAME time there's DC flowing through it. The presence of DC ON the AC load is irrelevant to an incandescent lamp... but what about the AC coming BACKWARDS into the relay? wouldn't 115vac burn up the relay coil? After all... 115v across a 452ohm resistance is about 255mA... that would be over 29 WATTS of dissipation, through tiny little wire...

Well, if the relay has lots of inductance, AC won't flow THROUGH the coil, so long as the coil's 'frequency limit' is lower than the frequency being applied. The magnetic field can only build and collapse so fast... Mebbie that coil will pass AC if it's flowing at say... 5hz... but at 20hz, it might as well be a brick wall... so at 60hz, there's no AC flow through the relay.

I could have bench-tested the coil... put an oscillator on the coil in my lab... and varied the frequency to 'look' for where it's cutoff point would be, but it would not have yielded a valid result- The relay's iron polepiece adds a substantial amount of magnetic density to that coil, so attempting to measure without having it in-situ would be pointless. A 450-ohm 3300 turn coil in free-air might pass AC up to oh... 300khz before hitting FCO (frequency of Cut Off), but inside that iron polepiece... it comes WAY down.

Henceforth, I await Allen's numbers, so I can do some more forensic engineering...
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
The coil of the Generator Relay which you repaired is never in the AC circuit.

It’s circuit consists of Exciter, normally closed auxiliary contact on the Cranking Contactor, Resistor, and the Generator Relay coil itself.

Likewise the load is never exposed to AC and DC at the same time. The Generator Relay switches between the two.

There are two separate load sensing coils on the Main Relay. The DC one and the AC one. The DC coil is in series with the battery and load through a normally closed contact on the Generator Relay. When the Generator Relay pulls in, it disconnects the load from this DC circuit, and connects it to the generator AC output through the AC load sensing coil of the Main Relay.

Clear as mud? ;)

Keith
 

Zephyr7

Registered
Could you put two twelve volt coils in series, you could parallel the contacts for extra load.
Yes, you can put two coils in series as long as they are identical in terms of resistance.

It’s generally not recommend to parallel contacts to increase current capability because they don’t make and break at exactly the same time, which tends to result in excessive arcing and premature failure of the contacts. If you don’t expect the relay to be switching under load then it doesn’t really matter, but if you’re using the relay to control a load you could potentially have problems.

BTW, dkamp, I doubt your coil will carry any current at 60Hz, especially with the core material in place. 3300 turns is a good amount of inductance even in air.

Bill
 

dkamp

eMail NOT Working
I agree, Keith- they SHOULDN'T be, but in many circuits, they ARE used this way, in the event that anyone in the future happens to read this, and attempt to replicate the coil reproduction that I've done, in a similar, but not identical application. I agree, Bill... at that frequency, especially with over 300ohms R, that there's enough XL to put the fCo way down into the single Hz.

And the 'surface level' point here, is that while this machine seems really old, and really low-tech, it's not. It's incredibly high-tech, even for today's time. To make an automatic start unit nowdays, you need a microprocessor and a mess of supporting circuitry, sensing lines, appropriate isolation, transient suppression, and a constant source of power. This happens with just wire, iron, and physics.

JB... yes, you could... but it'd take some tinkering, and perhaps swatting off frustration... to get it to react like the original part. One could make a 24Vdc relay using fewer turns of thicker wire, yielding a higher pull-in current at the same voltage, or more turns of smaller, yielding a lower pull-in current... or a different pull in point in voltage curve... which may, or may not cause an operational difference. I don't think this relay was ever in a circumstance that required more contact capacity... it just needed to be able to pull in, and drop out, at the right signal point.
 

Kohlerallen

Registered
So I'm feeling a combination of excitement and impatience to get Allen's measurements of AC, DC, and current readings... first, so I can compare the math and get an estimation of what the windings' survival time will be, and second, so I can get a really good concept of what they're being subjected to.

A relay is a gadget that has an electromagnet that pulls in contacts... but there's more. The coil is a conductor, which means current will pass through in either direction according to the limits identified in Ohm's Law with respect to resistance... that's where I calculated my 452 ohm result. But it's a coil of wire wrapped around a polepiece, which means it is also an inductor, which means it will pass in both directions, and in AC, up to a certain frequency, after which, it becomes more-or-less a 'brick wall'... because the magnetic field of that coil and polepiece is too dense to allow the current in the coil to change direction fast enough to allow current flow.

And here's where it gets interesting- An inductor can carry both AC and DC current at the SAME TIME. In this generator, the control system works on the principle that they're putting 24v across the plug, and sensing current flow through a light bulb. IIRC, it's a 40w minimum lamp required for it to 'sense' the presence of a load. With that load in place, a little bit of DC current flows through the lamp. Let's figure out how much current, at 24v, would flow through a 115v 40w lamp:

40w/115v = .347mA. That means the lamp's resistance must be 330 ohms.

If we apply 24vdc to a 330 ohm lamp, the current flowing is 0.073 amperes... 73mA.

In comparison, the 452 ohm coil winding, at 24v, would carry 53mA (and disspiating 1.27 watts)

Now, the coil winding would develop full magnetic draw at 53mA, applying 73mA means that the coil is at full capacity only two-thirds-of-the-way to the bulb's draw. This works out just fine, because they're not trying to 'illuminate' the lamp filament, they're just trying to determine wether it's THERE.

Now, once this generator starts, it's applying AC across that lamp, at the SAME time there's DC flowing through it. The presence of DC ON the AC load is irrelevant to an incandescent lamp... but what about the AC coming BACKWARDS into the relay? wouldn't 115vac burn up the relay coil? After all... 115v across a 452ohm resistance is about 255mA... that would be over 29 WATTS of dissipation, through tiny little wire...

Well, if the relay has lots of inductance, AC won't flow THROUGH the coil, so long as the coil's 'frequency limit' is lower than the frequency being applied. The magnetic field can only build and collapse so fast... Mebbie that coil will pass AC if it's flowing at say... 5hz... but at 20hz, it might as well be a brick wall... so at 60hz, there's no AC flow through the relay.

I could have bench-tested the coil... put an oscillator on the coil in my lab... and varied the frequency to 'look' for where it's cutoff point would be, but it would not have yielded a valid result- The relay's iron polepiece adds a substantial amount of magnetic density to that coil, so attempting to measure without having it in-situ would be pointless. A 450-ohm 3300 turn coil in free-air might pass AC up to oh... 300khz before hitting FCO (frequency of Cut Off), but inside that iron polepiece... it comes WAY down.

Henceforth, I await Allen's numbers, so I can do some more forensic engineering...
It looks like you hit the nail right on the head. Got my infrared thermometer back this morning, went right out to the garage. Temperature in garage was about 55 degrees, started the generator, measured running (loaded) voltage at the new coil, varied between 35.6 and 36vdc. Tried getting an ac voltage, could not get a reading. Multimeter ran all over from out of limit to a multitude of different numbers. So apparently no ac voltage. Temperature of the coil went up to about 58-59 degrees, but I think that was just as much the heat of the whole unit as anything else.
 

Kohlerallen

Registered
It looks like you hit the nail right on the head. Got my infrared thermometer back this morning, went right out to the garage. Temperature in garage was about 55 degrees, started the generator, measured running (loaded) voltage at the new coil, varied between 35.6 and 36vdc. Tried getting an ac voltage, could not get a reading. Multimeter ran all over from out of limit to a multitude of different numbers. So apparently no ac voltage. Temperature of the coil went up to about 58-59 degrees, but I think that was just as much the heat of the whole unit as anything else.
More numbers. I realized that I was taking the reading incorrectly, had positive lead on hot side of coil, negative lead on the other terminal of the coil. When I connect positive lead to hot side of coil and negative lead to the common ground of the unit I have a reading of 61vdc. This corresponds to the 60 volt unloaded reading I had before. If I connect the positive lead of the meter to the other lead from the coil the reading is 26 volts, a drop of 35 volts through the coil.
 

dkamp

eMail NOT Working
Hmmm... okay, so if the drop across the COIL is 26, that means it's carrying 58mA. If it's 36, it'll be carrying 80mA, and if it's 60v, it'll be 132mA.

A wild-running AC indication confirms that Keith's note (and the schematic) is true in that there's no AC going through the coil... and I'll note that... while the schematic indicates that there's no AC connection, that doesn't mean there's no AC to be found. Realize that this is a whirling ballroom of magnetism that (by virtue of it's vintage) is dancing the Charleston through it's bones. AC appears EVERYWHERE, and just because it's not 'supposed' to be part of a circuit, doesn't mean it won't BE there. I had a drill press that melted it's motor-start capacitor... and when I went to fix it, I found that it had 90vAC between it's top cover and iron base when it was totally DISCONNECTED from the wall... because there was a 7950v power line 5 feet above the roof of the garage directly overhead... )

I doubt the coil would last long, and would heat up LOTS at over 100mA. the voltage that matters here, is how much is being applied to the coil, so one lead on one side, one lead on the other... I think that's 26, not 35, and not 60ish. Especially if it's remaining ambient...
 
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