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John,
There are 5 different types of tubes in the set. Two types are used twice.
0Z4: Metal cold cathode full wave rectifier. Works a bit like a neon bulb and only allows electricity to flow only one way due to the ionization of the argon gas inside it. Main tube in the HT power supply.
12SK7: Metal remote cutoff pentode. In this set they are used simply as amplifiers, the first one takes the received radio waves and boosts them to a useable level for the next stage. The second is the second stage amplifier.
12SA7: Metal pentagrid converter. Specially designed for this type of radio circuit, it does two things; first it has an oscillator section that runs at 252kHz, the second takes that and mixes it with the boosted RF signal from the first 12SK7. This Intermediate Frequency (IF) mixing means that the overall amplitude of the circuit doesn't change across the tuning dial. Without it, signals at the low end of the dial would be loud and signals at the top would be quiet.
12SQ7: metal duplex-diode high-mu triode. One is used as the secondary detector (if you take the radio signal amplitude as an entire wave, the peak of the top wave cancels that if the bottom and your net energy delta is zero. If you remove half the wave then zero plus the change in amplitude can be used. It also has audio pre-amplification stage. The other one is the primary detector diode and the phase inverter for one half of the output.
14C5: Loctal variant of the 12V6, akin the the famed 6V6. Pair of these connected to each side of the output transformer. One is fed the preamp signal, the other the opposite of the preamp signal. As one pushes, the other pulls* the loudspeaker.
Learned a lot in school, the rest just from playing about with old junk.
Phil
*This is a lie but it makes sense to say it
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Volume and tone control. So far all the resistors have been at least 50% high in value and the capacitors all leaky. Phil
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Been busy. Stopping for tonight. Just got the top right corner to do.
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fascinating .. i am getting very tempted to take my sun tester apart and pester you
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May 24, 2020 12:52:04 GMT
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I've been taking it slow and trying to make sure it's done tidily and correctly. I've made a couple of position revisions to some of the components; now that they're smaller they can all fit in more akin to how the schematic says they're connected. Where it's not critical that the piece connects directly to the past of the circuit the diagram says it is, often the component you're searching for is connected a few inches away on a physically connected but totally different part of the circuit.
Also, removing all the old bits of leg of component you just removed, removing the old solder to expose the hole in the connector tang takes time.
I also had a "52 card pick-up" moment that took a bit of time to resolve when I dropped the open box of resistors on the floor and they all scattered. It was not long after that I called it a night...
That wasn't the worst part though. The worst part is dealing with those old yellow capacitors. They're cardboard, dipped in wax. Over time the wax has become unstable and it is nasty, dirty and sticky. I accidentally cut my finger yesterday morning cleaning the washing machine, and since then I've managed to make it hurt by getting lemon juice, floor cleaner and that old wax in it. Not ideal, really.
Phil
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Last Edit: May 24, 2020 12:54:41 GMT by PhilA
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May 24, 2020 13:24:57 GMT
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that sounds like a "i wonder what would hurt most" 11 years boys competition .
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May 24, 2020 21:44:26 GMT
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It is complete. It plays. Phil
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Static tastic ! well done phil ,bit of copper wire up the wall for an aerial ? or does it need ground plane and all the sort of thing like a cb aerial.
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May 25, 2020 12:17:24 GMT
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Static tastic ! well done phil ,bit of copper wire up the wall for an aerial ? or does it need ground plane and all the sort of thing like a cb aerial. Just a length of wire up the wall. Sounds a lot better with the battery charger disconnected. Get a lot of trash from the power line in so I'm going to work on filtering that, and the heater circuit which only has a rudimentary hash choke. Phil
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May 25, 2020 22:25:44 GMT
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Fixed the nonsense issues.
Plays good. Might get a more modern 6x9 with a mid and a tweeter because the power section is certainly capable of being fully HiFi.
Phil
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Super cool! And thanks very much for the education.
May I ask another question?
I was annoyed today because an LED 110V small work light I bought some months back at Home Depot continues to cause awful interference on the FM reception on my cheapo but reliable late 80's Sony dual cassette boom box I have in the garage and listen to (radio) while wrenching/spannering. Plugging in to an outlet of a different circuit helps a little, but not enough. Other than not using the lamp or listening to the radio, any suggestions? Are LED lights known to create radio interference?
Thanks, John
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Super cool! And thanks very much for the education. May I ask another question? I was annoyed today because an LED 110V small work light I bought some months back at Home Depot continues to cause awful interference on the FM reception on my cheapo but reliable late 80's Sony dual cassette boom box I have in the garage and listen to (radio) while wrenching/spannering. Plugging in to an outlet of a different circuit helps a little, but not enough. Other than not using the lamp or listening to the radio, any suggestions? Are LED lights known to create radio interference? Thanks, John Does it have the FCC Title 47 Part 15 statement on the back? (This device must not interfere nor accent interference from...) Or an Underwriter's Laboratories UL? If it does, then no. It should not cause an FM radio to hash. Unfortunately cheap light fixtures, particularly ones with diodes, cause a large amount of EMI and cancelling it out takes more electronics than a lot of Chinese curse word has in (oft just a dropper resistor and the CoB LED). If it has that statement it should have an FCC ID and you should be able to look it up. There's a lot of junk sold, even at big name stores, that doesn't conform to anything they print on the back. You might as well put the FCC statement on a potato in a lot of cases. Edit: It should have a sticker on it like this one. You can always contact UL and check if it's in compliance. Phil
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Last Edit: May 26, 2020 2:53:17 GMT by PhilA
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Phil H
Posted a lot
Posts: 1,448
Club RR Member Number: 133
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1951 Pontiac ChieftainPhil H
@philhoward
Club Retro Rides Member 133
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Bit like over here we have the “CE” mark.
Some cynics reckon it stands for “China Export”..
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Oh my. Phil
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really well done, Phil. Which resistor circuit allows that thing to play 60's, 70's & 80's music? JP
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I know its spelled Norman Luxury Yacht, but its pronounced Throat Wobbler Mangrove!
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The sneaky little addition bottom right. Phil
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Last Edit: May 27, 2020 3:46:10 GMT by PhilA
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that sounds plump and fruity , ,can't believe that all fits behind the dash , well done .
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Phil - Credit to you - you lost me at the start of the radio restoration when you took the cover off the set - 99% of other owners would have found a period looking radio off the shelf that is stuffed with modern workings - It's always nice to keep something has original as possible
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May 27, 2020 14:12:44 GMT
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Plays okay. Makes antenna go. Editing blip was to cut out the 6 second pause where my old phone decided at that point to be slow to pair the Bluetooth.
Phil
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May 27, 2020 15:26:01 GMT
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Does it get The Wolfman?
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