just was wondering if the NTE 236 can perform as well as the 1969 final when it comes to mod's ? as well as the NTE295 verses the 2SC2314 drivers ?
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Transistors ? 2SC1969 Verses NTE 236
- Thread starter Switch Kit
- Start date
you let me know when you see over 40 watts pep out of an NTE236. like when hell freezes over. if it can do that AND sell for less than $3.95 apiece then I'LL BUY THEM!
So I guess what your saying here Freecell is that "they" do not compare ? ...makes me wonder why Toshiba would stop production of the 1969s in the first place ? thanks for the reply S-K
Toshiba stopped making that kind of transistor 20-plus years ago. The 2SC1969 is made by Mitsubishi Semicondutor. A division of the same outfit that made the famous "A6M", or "Zero" single-engine fighter aircraft of WWII.
And an NTE 236 is a "re-marked" part. NTE is like Sears. They don't MAKE anything. They just buy in quantity, scrape the original markings off, and print their number on the part.
Odds are that a NTE236 will have started out its life with the number "2SC1969" on it before NTE scraped it off. Or it could be any one of a dozen other "close enough" types that NTE found for sale cheap in quantity. The problem with an NTE part isn't that the quality will be bad. The problem is with establishing the exact identity of the part BEFORE the number got scraped off. For a lot of transistors, in audio and DC power-supply circuits, the small differences aren't often a big deal.
RF circuits are different, and substituting a transistor almost NEVER works better, or as good as the original. It's like playing craps with your eyes closed. If the NTE "sub" is good enough everybody is happy. If it's only close, then the result you'll get will only be "close".
73
And an NTE 236 is a "re-marked" part. NTE is like Sears. They don't MAKE anything. They just buy in quantity, scrape the original markings off, and print their number on the part.
Odds are that a NTE236 will have started out its life with the number "2SC1969" on it before NTE scraped it off. Or it could be any one of a dozen other "close enough" types that NTE found for sale cheap in quantity. The problem with an NTE part isn't that the quality will be bad. The problem is with establishing the exact identity of the part BEFORE the number got scraped off. For a lot of transistors, in audio and DC power-supply circuits, the small differences aren't often a big deal.
RF circuits are different, and substituting a transistor almost NEVER works better, or as good as the original. It's like playing craps with your eyes closed. If the NTE "sub" is good enough everybody is happy. If it's only close, then the result you'll get will only be "close".
73
I stand corrected on Mitsubishi and not Toshiba .....why in the hell would they stop making the 1969 in the first place ? but then again ...why in the hell did they stop making the Grant XL's ? seems like such a popular transistor ...and what will happen now when it comes to these 1969 AM radio mods ?
Hi Switch Kit,
The real question isn't why did they quit making them, but why did they stay in production for so ridiculously long?
Most semiconductor products have a pretty short life. New technology displaces old stuff in 3 or 4 years or less, in most industries. The need for government approval "freezes" parts of the design for a CB radio, just so it will be legal to sell. Until you get a new one approved. It's just business. Most "old" device designs get sold off to a lower-cost vendor who buys the manufacturing license from the folks who invented the part. The "RCI8719" is an example. There was enough of a market for the chip that RCI could hire a "generic" manufacturer to make a copy, long after Fujitsu stopped making ANY analog chips.
The 2SC1969 is a 25-plus year-old component design. That's an insanely long life for a transistor type. The reason is always the same. Mitsubishi couldn't make money making them any longer. Just business.
Gotta figure some lower-cost (lower-quality) outfit will either license the original part, or just make their own "clone". In China, spending money on a manufacturing license is considered silly. Who's gonna take them to court in China? ? ?
Besides, if there are any patent issues, that patent has either expired, or will soon. Mitsubishi recovered their up-front cost to develop the part 20-plus years ago. When making it stopped being a low-cost cash cow, they stopped. Just like the D-104.
Same reason again. The bandit radios with more power, channels and knobs were kicking their ass in the market. A legal radio with high manufacturing quality (and cost) just doesn't compete with cheaper stuff.
Kinda like buying a 8950 tube. A big, loud CHA-CHING ! !
73
The real question isn't why did they quit making them, but why did they stay in production for so ridiculously long?
Most semiconductor products have a pretty short life. New technology displaces old stuff in 3 or 4 years or less, in most industries. The need for government approval "freezes" parts of the design for a CB radio, just so it will be legal to sell. Until you get a new one approved. It's just business. Most "old" device designs get sold off to a lower-cost vendor who buys the manufacturing license from the folks who invented the part. The "RCI8719" is an example. There was enough of a market for the chip that RCI could hire a "generic" manufacturer to make a copy, long after Fujitsu stopped making ANY analog chips.
The 2SC1969 is a 25-plus year-old component design. That's an insanely long life for a transistor type. The reason is always the same. Mitsubishi couldn't make money making them any longer. Just business.
Gotta figure some lower-cost (lower-quality) outfit will either license the original part, or just make their own "clone". In China, spending money on a manufacturing license is considered silly. Who's gonna take them to court in China? ? ?
Besides, if there are any patent issues, that patent has either expired, or will soon. Mitsubishi recovered their up-front cost to develop the part 20-plus years ago. When making it stopped being a low-cost cash cow, they stopped. Just like the D-104.
Same reason again. The bandit radios with more power, channels and knobs were kicking their ass in the market. A legal radio with high manufacturing quality (and cost) just doesn't compete with cheaper stuff.
Kinda like buying a 8950 tube. A big, loud CHA-CHING ! !
73
I enjoyed reading your post there ,makes sence I suppose. About a year ago I was able to get 1969s for about 2.00 ,now there 5.00 ,I wonder if it might be profitable to get about a dozen of them and put them away for safe keeping ? I suppose there really not that important to me. 8950s!!! CHA-CHING IS RIGHT !!!!! thanks for the reply nomad.
someone is charging you way too much for 2SC1969's. RF Parts still sells them for $3.95 a piece.
RF Parts is good enough but you have to spend over 25.00 + Shipping for them to do business with you. I suppose one's got to do what ones got to do .
2sc1969 mosfet replacement
I've put an IRF510 mosfet in a Cobra 25, cost 50 cents. I had to change a couple of caps and put the tuning slugs back in the coil forms. It's dead keying 4 watts and swinging to 17. The IRF510 is rated at 100volts so my next mod is bypassing the 13.8 volt supply to the final. Then ........... 20~30 volts.
Monk
I've put an IRF510 mosfet in a Cobra 25, cost 50 cents. I had to change a couple of caps and put the tuning slugs back in the coil forms. It's dead keying 4 watts and swinging to 17. The IRF510 is rated at 100volts so my next mod is bypassing the 13.8 volt supply to the final. Then ........... 20~30 volts.
Monk
A 510? No joke?
I thought that one ran out of steam above 10 or 15 MHz.
Did you use the stock thermoplastic shoulder washer to hold it down? If the efficiency is too low, the heat will catch up with it, even if the wattmeter looks good. If it reaches the melting temp of the nylon shoulder washer, it pulls away from the heat sink, and POOF.
The IRF510 is an enhancement-mode device. Seems to me you would need to place some DC voltage onto the gate to get full power gain. Trouble is, you'd have to switch off the bias for receive, like in a SSB radio.
Gotta wonder what the optimum value for the resistor on the (now) gate? Pretty sure the stock resistor to ground on the (stock) base leg of the final is 22 ohms. That might be the best choice for the 510, or you might get more drive from it with a different resistance value.
IRF510s really are cheap and widely sold. Gotta buy a few and try this. Even if it's no good on a SSB radio, this could be a useful answer to the disappearing 1969/2312, even if it's only useful for AM-only models.
73
I thought that one ran out of steam above 10 or 15 MHz.
Did you use the stock thermoplastic shoulder washer to hold it down? If the efficiency is too low, the heat will catch up with it, even if the wattmeter looks good. If it reaches the melting temp of the nylon shoulder washer, it pulls away from the heat sink, and POOF.
The IRF510 is an enhancement-mode device. Seems to me you would need to place some DC voltage onto the gate to get full power gain. Trouble is, you'd have to switch off the bias for receive, like in a SSB radio.
Gotta wonder what the optimum value for the resistor on the (now) gate? Pretty sure the stock resistor to ground on the (stock) base leg of the final is 22 ohms. That might be the best choice for the 510, or you might get more drive from it with a different resistance value.
IRF510s really are cheap and widely sold. Gotta buy a few and try this. Even if it's no good on a SSB radio, this could be a useful answer to the disappearing 1969/2312, even if it's only useful for AM-only models.
73
Norm,
I mounted it just like the regular final, no leg twisting. I used the insulator, grease, and collar.
I didn't think the 510's went this far into the HF until I ran across an article on the web about eight 510's on 6 meters. The guy built a amp using four of the mosfets in parallel on each side and then the regular input and output transformers.
On the mosfet thing I went to the RF Parts site yesterday and the have a new listing for a 16 watt 12.5 volt HF in the 220 case.
I suspect that RM of Italy is using the standard off the shelf mosfets in their line of amps, KL40, KL60, KL203 because they grind off the part number.
Monk
I mounted it just like the regular final, no leg twisting. I used the insulator, grease, and collar.
I didn't think the 510's went this far into the HF until I ran across an article on the web about eight 510's on 6 meters. The guy built a amp using four of the mosfets in parallel on each side and then the regular input and output transformers.
On the mosfet thing I went to the RF Parts site yesterday and the have a new listing for a 16 watt 12.5 volt HF in the 220 case.
I suspect that RM of Italy is using the standard off the shelf mosfets in their line of amps, KL40, KL60, KL203 because they grind off the part number.
Monk
rm-3 are the 510's been using them as replacements in klv amps now for over a year never hed one come back. also in the 2000 arrl handbook there is an amp plan that uses them. the klv amps are almost the same design but without the filtering and biasing.