I guess that I am making some kind of mistake here??

Well, keep going - some assembly required - that means you...as in ...have to do it...

Just remember the MRF497 is a BEC not a BCE pinout. Meaming if you try to wire this up without making the proper changes, BOOM.

That means the Emitter is to the TAB and Center leg, not like the older parts they replace which a 2312 uses BCE and the 1969 is also BCE - get a datasheet for these parts as you can - it helps to review them when you want to go big, you can wire it up right and not go boom...

PDF's attached...look for them at the bottom of this post before the next post...The 2312 and 1969 are also included - and you'll see by the detail drawing they use COLLECTOR to TAB - while the MRF-497 is EMITTER to TAB - meaning it is not a drop-in working part.

Verify the parts you get are genuine.

And more than likely without additional parts changing those finals won’t get you where you think they will. Probably. Maybe.

Doc: Unless it Broke...don't though money down the drain on that radio to mod it...Just buy a real radio!~~~~ And be done with it!
Plenty of good equipment out there that will out preform anything made by Galaxy/RCI...etc...
Then put up a decent antenna farm...And have fun.
All the Best
Gary/W9FNB

I don’t care what YouTube tech told you that you’d gain power by just swapping in those finals and those finals only, I’ll say he’s wrong. I don’t care if he has 125yrs of experience. That circuit is designed for the transistors that are in it from the factory. And you won’t have the gain needed to reach some massive power level, not without additional work.

If you could, everybody would just build the same radio, the same way. I’ve personally seen those very transistors swapped into a radio and there was very minimal power gained because nothing else was changed. And if you only gain 5, maybe 10 watts peak, what have you actually accomplished? Nothing.

I wasn’t trying to be condescending in my comment, I was only making a statement, typing what I was thinking. It’s your radio and you already have the transistors, swap away. But when you don’t see massive power gains don’t be surprised. Now possibly if you rework the entire output side to supply enough drive to those transistors then you’ll possibly see a big enough increase to make it worth your time and effort.

Otherwise, I agree, if it’s not broke then don’t try to fix it and if it’s not doing what you want then don’t throw money at it (down the drain). You’d be better better off getting an amp or just buying a totally different radio.

RPC,
Was your Post #41 directed toward me or Doc?
Just curious.

Doc: Unless the mod will more than DOUBLE the power output...it is not worth the effort...Doubling your power increases your signal only 3db...which by most standards is One Half of one "S" unit and barely detectable by the human ear...The masses don't believe this but TRUE...to truly gain anything on a 25 watt radio you need to jump to 100 watts for it to be worth anything...MHO
All the Best
Gary

Riverman71 said:

RPC,
Was your Post #41 directed toward me or Doc?
Just curious.

Click to expand...

Doc. It was just rambling basically. I meant it humorous but I guess you’d have to have seen Billy Madison to get the way I meant. I wasn’t trying to be hateful to him.

TheRealPorkchop said:

Doc. It was just rambling basically. I meant it humorous but I guess you’d have to have seen Billy Madison to get the way I meant. I wasn’t trying to be hateful to him.

Click to expand...

No, I got it.
It just showed up shortly after my humorous post and I thought it was for me.

FULL _MEDIC,

Replacing the finals in your radio is not going to make one hill of beans of difference to any receiving radio. not to mention that you need to modify the circuit to be able to get the power out of those 497's. they are not just a drop in replacement.
also, are you sure the 497's you got aren't fakes? 99% of the 497's available and 100% of the 497's available on ebay are fakes.
could you post a picture of the ones you got so that we can confirm whether or not you got the real deal?

here's the straight scoop when it comes to increasing your power output.
you have to increase your power by a factor of 4 in order to increase your signal by 1 S unit in someone's receiver.
that means that if you deadkey 10 watts now, and hit someone with an S-5, you will have to deadkey 40 watts to hit them with an S-6. this holds true regardless of how much power you are talking about.

the diode you referred to is being used to vary the bias on the driver or final depending on the temperature. it is not a varactor diode. A varactor diode varies it's capacitance based on different voltages coming into it. the NTE610 that was recommended to you is a varactor diode and is not the right part to put in the bias diode spot.

LC

Well in the voice of James Earl Jones, “just what is it that we still never know”?

Is it that each of those is 40w so you’re thinking together you’ll end up with 80w? Ain’t gonna happen brother, so you’re not gonna get your moneys worth. What exactly are you expecting from them, you’ve never said I don’t think?

I think what you’re gonna do is butcher a radio and in the end have one that works just about the same as it does now or won’t work at all. Is it worth that? Not to me. Been there, done that.

But in the words (more the voice) of Bobby Boucher’s momma...”you go have fun playing the foosball with ya friends”. Or in your case, putting your finals in your radio. Good luck.

When someone has loosened the mounting hardware on those transistors. It means several things.

One, they swapped in part to "try and see if it works"

Two - the radio may work with them in, so let's push it off to someone else that can take care of this.

Three - the radio is toxic...

Toxic means it's been exposed to and worked on by other people that don't know what they are getting into - and now it's transferred over to you.

It's like a patient that was in for a simple appendectomy - has now turned into a bleeder that needs a crash cart and 2 liters of blood to replace what the darn triage trainee left for you to fix. The Anesthesiologists just went outside for a cigarette and your left with a mess and nurses that are looking for a trash can to lose their cookies in...

Good luck Doctor.