My first post has the dual conversion MB8719 chassis (Cobra 148GTL, Uniden Grant (XL), Cobra 2000GTL), so check there. I need to do up the PLL 02A Cybernet AM/SSB chassis.... I keep forgetting to post it! 
~Cheers~
~Cheers~
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MOSFET conversions for upD858 and MB8719 boards
- Thread starter ExitThirteen
- Start date
good luck finding even one radio on earth that shows 6db for a s unit. after I read an old thread about ham radois being as low as 1 to 2db an s unit ive tested mine with a couple gyus who can ajust there power and its more like double the power for a s unirt
im bumping this thread because its xlnt information
No; re-alignment is unnecessary when putting in the MOSFET.
If you have a 1307 final, I wouldn't change a thing.
If you want more power; then run a 200w amp . . .
Ok, I do have that final. I have an amp I have to replace the pills in, just curious as to what difference I would get. I'll be saving this info though in ase that final craps out on me. My buddy has the uniden washinton with 8719 pll and the 1969 finals.
1306 driver and 1307 final combo is just fine if it is working, and I doubt you will ever find those transistor`s any more....rare as hens teeth.
73
Jeff
73
Jeff
got a couple of those old nec (if they ain't nec they ain't real) hen's teeth here.
if your final craps out replace it with a 2sc2312 or 2sc1969 eleflow transistor. they work well and can be got on e bay cheaply.
That is E-bay gold right there Jazz.
Put them up for Auction with words like Vintage, rare, no longer made, new old private stock, stored in a temp controlled, moisture and smoke free environment.
Take pictures of you removing them from sealed 1 gram zip lock baggies while wearing latex gloves and holding them with a pair of stainless steel forceps, or even better yet, do a you-tube video with music playing in the background like the guys at cobraworxshops.
Add that they are Original replacements for Vintage, Rare No longer made, collector Radios, and start the bidding at $100.00 each with a $400 reserve.
e bay is just chock full of guys with $$ signs in there eyes for stuff like that.
73
Jeff
got a couple of those old nec (if they ain't nec they ain't real) hen's teeth here.
if your final craps out replace it with a 2sc2312 or 2sc1969 eleflow transistor. they work well and can be got on e bay cheaply.
HFR-20W (2SC1969) ELEFLOW HF/RF TRANSISTOR....1pc. | eBay
You using a 56k ohm resistor to the 13.8V on the RF choke? That should put the voltage at 3.65 volts or so. I still have the MOSFET in my President Washington from about a year ago, and it works great.
Just remember that you have to follow my instructions to the letter for optimum performance. Keep trying, you'll get it.
~Cheers~
Just remember that you have to follow my instructions to the letter for optimum performance. Keep trying, you'll get it.
~Cheers~
You using a 56k ohm resistor to the 13.8V on the RF choke? That should put the voltage at 3.65 volts or so. I still have the MOSFET in my President Washington from about a year ago, and it works great.
Just remember that you have to follow my instructions to the letter for optimum performance. Keep trying, you'll get it.
~Cheers~
Yes, I had to use a different companion part. (i had irf510's and 520's) But, after you get itall in, the resistor and the mosfet, I can't really tune up the tx as the instructions say. When I start to turn the tuning slugs, the voltage at the gate rises. The old VR for the final bias has no effect. So, IOW, I only get about 6 watts out of it with the tuning slugs in almost the stock location, so as to keep the voltage at the gate at 3.65 vdc. If I try and "peak" it like the sock finals, it smokes the mosfet.
Can you take a picture of the underside of the radio where you have the resistor mounted? Tuning the slugs shouldn't be raising the gate voltage. Mine stayed at 3.65V no matter what I tuned in the radio... I'm wondering if you're pulling voltage off a different source somehow, or you didn't remove a component that cuts off the original biasing circuit. Shoot me a good pic, and I can help troubleshoot.
~Cheers~
~Cheers~