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MOSFET conversions for upD858 and MB8719 boards
- Thread starter ExitThirteen
- Start date
Shouldn't be... I can take pics of my Washington inside, and show you what mine looks like.
~Cheers~
~Cheers~
Did you even get a chance to snap a few of those pics? I am still having issues with this Washington, good thing I have the Saturn to talk on. I would like to convert the driver and finals to mosfets, cheaper. The 1306 and 1307 are long gone. I think when I did the conversion at first, I have a different circuit than u. Seems someone before changed a few things. I have a factory schematic, but I am almost afraid to put it back to the schematic. 
The driver and final circuit look like a cross between a 139lxr service bulletin and stock.
I plan on ordering the parts and trying it exactly like the schematic says, but it doesn't include the 47Ohm resistor from the base to ground on the schematic.
Anyhow, if you could take a few good pics of what you have I would appreciate it! Thank you
The driver and final circuit look like a cross between a 139lxr service bulletin and stock. I plan on ordering the parts and trying it exactly like the schematic says, but it doesn't include the 47Ohm resistor from the base to ground on the schematic.
Anyhow, if you could take a few good pics of what you have I would appreciate it! Thank you
$15-$20 is too much for a 2SC1969? I would pay that any day instead of a mosfet conversion for $4. You will go through 6-12 mosfet finals before blowing a 1969.
I still don't see the problem even if that was the case... You can buy 25 International Rectifier IRF520 mosfets for around $15 SHIPPED... in general most radios only need a handful of inexpensive parts to get up and running... and USUALLY you will see better numbers on the meter. In some cases even doubling peak power output.
I mean let's say that you have an Cobra 29 LTD. In this 29, you install a 2sc1969 and let's say you get 25-30 peak... On the same radio with an IRF520, and the correct companion parts, guys are getting 35 on the low end and as much as 50 watts on the high end.
To me that seems like a good reason to look at mosfets. My personal best on a mosfet Cobra 29 was 48 watts. (last I heard it was still working and the owner is quite proud of it.) Mosfets run pretty cool from what I have seen. They are also dirt cheap even for the quality ones.
Another thing to consider is as of late China has been working very hard to produce FAKE NEC 1307 and 2sc1969 finals. I have even seen some that were 'NEW', but it was easy to tell that they had just been carefully cleaned up and sold as new.
If you go with mosfets, just make sure you buy from a quality company and a quality brand, I normally go through Jameco. Further more make sure you use the correct companion parts. As for old school transistors, just make sure they are real and there is nothing to worry about.
Either way, eventually you will not have a choice, eventually the transistor, like the dinosaurs will simply go extinct.
ALSO this might be useful to some of you guys. The EKL parts are quick and usually get you close, but sometimes you get better results by changing a few values.
CBTricks MOSFET Experimenter's Information Notes
lol, to each their own. But you should just get used to it. Transistors are on their way out
Think he was talking about these:
These are the 'companion parts' that are needed to make the MOSFET work.
CBTricks MOSFET Experimenter's Information Notes
Since the Eleflow company now makes the CB-20w/2SC1969 as a replacement part, MOSFETS aren't all that necessary to use. But it is still nice to know there is an option just the same . . .
Yes, Robb is correct. Those are the companion parts that I am speaking of. They can be bought thru Copper, H&Y, RF Parts and some CB shops.
I've been doing MOSFET mods on these boards for a few years now, but I wasn't going to post information about it if I didn't think it wouldn't be reliable, or if the mods caused the radio to perform poorly. Certainly nothing new, but useful if someone wanted to experiment, or wanted to keep costs down when replacing finals.
The first D858 Washington I did is still in service today, it's been over 3 years. Still sounds good, still puts out about 25W on SSB.
~Cheers~
I've been doing MOSFET mods on these boards for a few years now, but I wasn't going to post information about it if I didn't think it wouldn't be reliable, or if the mods caused the radio to perform poorly. Certainly nothing new, but useful if someone wanted to experiment, or wanted to keep costs down when replacing finals.
The first D858 Washington I did is still in service today, it's been over 3 years. Still sounds good, still puts out about 25W on SSB.
~Cheers~
