TRC 474 swing kit or mod?

[Night Crawler]

D19 is correct it is the AMC diode for the 474 the one I have had it already removed when I got it so I left it out in any case in or out it's up to you.
There shouldn't be any problems with it being removed.

Check your PM.

[dime196604]

just checking with you on one more thing. I will be cutting the trace on the back of the board. the leg from L8 that faces the front of the radio, the trace to that leg on the back side leads to the back of the radio. it a small curved trace about 3/4 inch in length. i use a light to see the traces trough the board. just wanted to mack sure it was the correct one

[Night Crawler]

That is the correct trace another thing to add make sure you cut it as close as possible to L8 because that trace also feeds the modulated B+ to the final I explained how I did it in the PM. If you decide to use the variable mod with the transistor you will find that it works much better then a fixed resistor and capacitor and it is adjustable from 0 watts to the full output of your radio.

[dime196604]

Ok thanks again very much

[tubehead]

can somebody explain what exactly happens when you do this mod? hows it work?

[Night Crawler]

Here's a video from one of the members on the forum that will show you.
http://www.youtube.com/watch?v=BHA7aY9IbtU

[dime196604]

ok mod is done but i'm not liking it too much. my dk is 2watts and swings to 5 and the capacitor gets hotter then hell after only 2 or 3 seconds of keying up. I'm thinking i'm just gonna pull the plug on this. i have tried a few different caps and resistors but the only thing i get is a lower DK. Before the mod my radio DK was about 3 to 4 watts and swinging to almost to 8 sometimes so i'm just gonna put it back the way it was. it was a interesting project though

[Night Crawler]

I never used the cap and resistor did you try the variable one with the transistor that's the one I used and it worked fine for me.

[dime196604]

No but i planed on trying it. what is the dk of your radio? and what does it swing to?

[dime196604]

is the "Ultra-Mod Variable Power" you talked about in another persons post the same thing you showed me how to build? if not how does that one work?

[Night Crawler]

what is the dk of your radio? and what does it swing to?

With the variable using the transistor I can take it down to zero watts or set it anywhere inbetween 1,2,3 watts etc on peaks it does maximum output.
Don't expect it to give you anymore output then your radio already does the swing kit will not increase the output wattage of your radio.

I'm curious you said that the capacitor was getting hot that shouldn't happen are you sure it wasn't the resistor and if it was what size wattage did you use? You need at least a 1 watt resistor to handle the current.

is the "Ultra-Mod Variable Power" you talked about in another persons post the same thing you showed me how to build?

It's the same thing I cracked one open to see what was inside it also goes by the name of "Super Talk"

[dime196604]

i first started with a 100ohm 1 watt and that cut my dk to .20 watts a the swing was only 2 watts so i when with a 68ohm and that did a dk of 2 watts and swing of 6 watts, but my output before the mod was about 7.8 so almost 8 watts. and with every one the resistor got very hot i tryed a 220uf 16v a 470uf 16v and a 32v and even a 1000uf 16v. i might try 2 of the 100ohm 1 watt resistor next just to see what happens. Does this radio have that black diode next to the modulation transformer you talk about in another post? if so how would i go about putting the mod there?

[Night Crawler]

Does this radio have that black diode next to the modulation transformer you talk about in another post? if so how would i go about putting the mod there?

It does it's marked on the the PCB layout that I posted on the first page as D18 but I don't remember if it's using the same number in the 474 but it will be in the same location on the board.

The positive side of the cap and resistor would go to the banded end of the diode and the negative side to the empty hole. If I were you I would use the variable with the transistor you'll find that you will have better results.

[dime196604]

The only reason i'm thinking about putting the mod there is that i ahve put in and taken out so much i don't wanna solder on them traces no more i don't wanna ruin them.

[Night Crawler]

I understand put it there then it will work fine if the resistor gets hot use one of these RS# 271-133 if 50 ohms is not enough put two in series which will give you 100 ohms if too much put the two in parrallel which will give you 25 ohms I'd be surprised if they get hot.

[dime196604]

Ok thanks much once again, so if i put one resister after another, it doubles, and if i put them parallel it cuts in half, right? I'm new to electronics and can't really read schematics too good but that why i like the one you sent me because it shows the exact place of parts and that one shows you plus the number not just symbols and the number, those kind just leave me lost and confused.

[dime196604]

If i do put it in place of the diode would i need to hook it in to the diode as you said or could i just remove the diode and put it in its place? would that make any difference?

[Night Crawler]

Ok thanks much once again, so if i put one resister after another, it doubles, and if i put them parallel it cuts in half.

You got it but only with equal value resistors it won't if the resistors are of different values.

Resistance Calculator
Series http://www.csgnetwork.com/ser ... tcalc.html
Parallel http://www.csgnetwork.com/par ... tcalc.html

[dime196604]

hey nightcrawler could i use a volume control from a old cb for the pot? i have a few vol, and squelch knobs just laying around you think i could use them for the control of the variable swing. they have three connectors just like the digram shows.

[Night Crawler]

That should work I used the tone control in the 474 I have and it works fine.
One thing I wanted to mention when I first tried that mod I had it connected to the Flyback Diode (as they call it the anti-spiking diode)and it worked fairly well what you could do which will give you a watt or two more is remove that diode and solder the #4 wire in the empty hole where the banded end of the diode went and the #3 wire to the empty hole where the unbanded end went.
I also tried that before I moved it to the coil going to the collector of the driver which seemed to be the best way to do it.