just picked up a ranger radio it has the channel mods done and rb mod echo and clarifier mods done to it but heard can put a npc mod in does anybody know where it goes on board ? thanks..........
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Ranger 696FD1
- Thread starter dejaskysdad
- Start date
there is a little more to the npc/rc mod than just putting a part in it. 1st off check to make sure there has not been a mod to R264 resister by adding a diode to it. the resister is by VR14. the mod would have to be reversed to do the npc/rc mod.
for the npc mod you have to put a diode and resister soldered together and install it to a capacitor. then the center pin at the mirror board jumper has to be removed then you solder a wire for the full 13.8 volts to the location of the center pin you would remove. then the bias has to be set . you have to make sure no one has removed the limiter also or the radio would splatter on ssb.
if you have the means to do this I could get you the actual info to do the mod. let us know if you can do the mod and I will round up the info.
In order to do the NPC mod you MUST have a scope, and I would suggest the non-volted final version called PPE. That said here is some good information from one of the better techs in the country on this mod.
Written by SS8541 Richard Byrd-
The npc mod is the most used mod in export radios today. it has been around for yrs, but it is set up wrong and actually labeled wrong (depending on form used) by 90% of the techs using it.
The npc where the limiter is removed and the final/s volted -is- an actual npc. but after reading this i hope you all will see that unless you have the right equipment it is unaceptable for a clean signal (which is the reason for using the npc instead of clipping the limiter). even when set right, a 1w carrier with 35-45w (single or dual final)of swing is not good.
For the npc where the limiter is left intact and and the final/s is not volted, a stock radio set at 100% mod by the factory, needs nothing but the npc components. well, the high power carrier needs reducing to keep the pos peaks from flattopping, but the lower power setting needs nothing but the npc components. this mod is also not truly a npc mod, but a ppe (positive peak expansion) mod. there is no compression of the negative peaks, since the neg peaks still hit 100% mod without the amc being adjusted, but the pos peaks will hit 125-300% pos mod (depending on resistor value used).
The reason is because the amc is only triggered on the neg peaks. the amc is turned off on the post peaks, but it tracks on the positive peaks by an rc circuit.
Here is a galaxy 77hml at 100% mod and a 1.25w carrier as an example....
For a 1.25w carrier the collector of tr51 is at 2.50vdc. the emitter of tr49 is at 2.54vdc. when audio is applied for 100% mod, the collector of tr51 swings from 0-5v (5vp-p). the emitter of tr49 swings from 2.49-2.59v (.1vp-p).keep in mind that the emitter of tr49 only swings .1vp-p as this will be revisited later. the amc samples the neg peaks to keep it at 100% mod.
Now when a 1n914 diode/390ohm res npc (ppe)is used, things begin to change. the banded end of the diode goes to the collector of tr51 and the res goes to the emitter of tr49. the neg peaks still hit the 100% mod i had set the radio for in the last step, but the pos peaks go to about 200%. remember how the voltage on the col of tr51 goes to 0 but the voltage on the emit of tr49 only goes to 2.49v. so when the col of tr51 goes .6v lower than the emit of tr49, the diode is turned on and -tries- to pull the col of 51 back up. but the amc is set to -make- the voltage of the collector of 51 hit 0 (100% neg mod). to do this more audio must be dumped into 49. this is evident by remeasuring the voltages at the emit of 49 with a scope. it was .1vp-p with audio, now it is .2vp-p. since the amc only samples the neg peaks, that same .2vp-p is present on the pos peaks. and since only .1vp-p is needed here, the pos peaks go past 100% (about 200% here). so as you can see, there is no compression of the negative peaks (npc). there -can't- be if the neg mod is hitting 100% before and after the mod without amc being adjusted. but there is positive peak expansion (ppe). this is all done by a way of fooling the limiter/amc. and you can add this to any stock radio and it will work properly as long as it was properly set at the factory for 90-100% mod. you also need to keep the carrier at no more than 3.5w for single final radios and 5w for dual finals for the 390/914 npc(ppe). for a 560/914, 5w carrier for single and 7w carrier for dual finals.
As for the npc where the limiter is removed and finals volted, there -is- neg peak compression since there is no limiter present to react and -force- the neg peaks to 100%. BUT you have to have a scope to set it correctly. and how many of you have that??? you may also have to play with resistor values or mic gain to get it to work properly (once again you still need a scope).you might as well just clip the limiter, since if you don't have the right equipment your in the same shape, but with about 5min-30min (depending on your soldering skill level) more work. also, why volt the finals when with both mods you have to reduce the high power carrier for it to work properly? the reg is being "spared" by reducing the carrier power (which is the reason for "volting" the finals).
Anyone who wishes to post this on other forums has my permission. I'm not doing this to call anyone out or for self recognition, but i'd like to see this get around for techs who don't quite understand what is going on with this/these mods (especially since this is the most popular mod out there). this mod was meant to run clean radios with increased pos mod, so it should be understood how to do it properly. I'm not a "mad scientist" saying it works because I say so. I laid down the facts to prove it.
by
SS8541 Richard Byrd
Also there are many many old threads here if you do a simple search for NPC mod. Here is one.
http://www.worldwidedx.com/cb-radio-modifications/133882-npc-mod.html
Written by SS8541 Richard Byrd-
The npc mod is the most used mod in export radios today. it has been around for yrs, but it is set up wrong and actually labeled wrong (depending on form used) by 90% of the techs using it.
The npc where the limiter is removed and the final/s volted -is- an actual npc. but after reading this i hope you all will see that unless you have the right equipment it is unaceptable for a clean signal (which is the reason for using the npc instead of clipping the limiter). even when set right, a 1w carrier with 35-45w (single or dual final)of swing is not good.
For the npc where the limiter is left intact and and the final/s is not volted, a stock radio set at 100% mod by the factory, needs nothing but the npc components. well, the high power carrier needs reducing to keep the pos peaks from flattopping, but the lower power setting needs nothing but the npc components. this mod is also not truly a npc mod, but a ppe (positive peak expansion) mod. there is no compression of the negative peaks, since the neg peaks still hit 100% mod without the amc being adjusted, but the pos peaks will hit 125-300% pos mod (depending on resistor value used).
The reason is because the amc is only triggered on the neg peaks. the amc is turned off on the post peaks, but it tracks on the positive peaks by an rc circuit.
Here is a galaxy 77hml at 100% mod and a 1.25w carrier as an example....
For a 1.25w carrier the collector of tr51 is at 2.50vdc. the emitter of tr49 is at 2.54vdc. when audio is applied for 100% mod, the collector of tr51 swings from 0-5v (5vp-p). the emitter of tr49 swings from 2.49-2.59v (.1vp-p).keep in mind that the emitter of tr49 only swings .1vp-p as this will be revisited later. the amc samples the neg peaks to keep it at 100% mod.
Now when a 1n914 diode/390ohm res npc (ppe)is used, things begin to change. the banded end of the diode goes to the collector of tr51 and the res goes to the emitter of tr49. the neg peaks still hit the 100% mod i had set the radio for in the last step, but the pos peaks go to about 200%. remember how the voltage on the col of tr51 goes to 0 but the voltage on the emit of tr49 only goes to 2.49v. so when the col of tr51 goes .6v lower than the emit of tr49, the diode is turned on and -tries- to pull the col of 51 back up. but the amc is set to -make- the voltage of the collector of 51 hit 0 (100% neg mod). to do this more audio must be dumped into 49. this is evident by remeasuring the voltages at the emit of 49 with a scope. it was .1vp-p with audio, now it is .2vp-p. since the amc only samples the neg peaks, that same .2vp-p is present on the pos peaks. and since only .1vp-p is needed here, the pos peaks go past 100% (about 200% here). so as you can see, there is no compression of the negative peaks (npc). there -can't- be if the neg mod is hitting 100% before and after the mod without amc being adjusted. but there is positive peak expansion (ppe). this is all done by a way of fooling the limiter/amc. and you can add this to any stock radio and it will work properly as long as it was properly set at the factory for 90-100% mod. you also need to keep the carrier at no more than 3.5w for single final radios and 5w for dual finals for the 390/914 npc(ppe). for a 560/914, 5w carrier for single and 7w carrier for dual finals.
As for the npc where the limiter is removed and finals volted, there -is- neg peak compression since there is no limiter present to react and -force- the neg peaks to 100%. BUT you have to have a scope to set it correctly. and how many of you have that??? you may also have to play with resistor values or mic gain to get it to work properly (once again you still need a scope).you might as well just clip the limiter, since if you don't have the right equipment your in the same shape, but with about 5min-30min (depending on your soldering skill level) more work. also, why volt the finals when with both mods you have to reduce the high power carrier for it to work properly? the reg is being "spared" by reducing the carrier power (which is the reason for "volting" the finals).
Anyone who wishes to post this on other forums has my permission. I'm not doing this to call anyone out or for self recognition, but i'd like to see this get around for techs who don't quite understand what is going on with this/these mods (especially since this is the most popular mod out there). this mod was meant to run clean radios with increased pos mod, so it should be understood how to do it properly. I'm not a "mad scientist" saying it works because I say so. I laid down the facts to prove it.
by
SS8541 Richard Byrd
Also there are many many old threads here if you do a simple search for NPC mod. Here is one.
http://www.worldwidedx.com/cb-radio-modifications/133882-npc-mod.html
It is important to both note and realize that removing the AM limiter isn't necessary to make the NPC mod work correctly. It is a myth to continue thinking that it is necessary. Because the AM limiter can also be simply made ineffective and left in the circuit by placing enough resistance (usually 1.5k ohms will do) between its voltage source to the base lead of that same transistor. This keeps the SSB circuit intact and allows for proper SSB function to work as it was designed. While removing the limitations that the transistor would otherwise provide if unaltered. No need to sacrifice the radio's overall usefulness for just AM mode of operation. You can have your AM cake and eat SSB too.
Few people who do the NPC mod operate or adjust it correctly. As adjusting the driver current to render the best scope reading is essential for success. Not to mention, adjusting the AM modulation level so that the waveform stays symmetrical - is also just as important for overall success. There are simply too many people just swapping out parts and just turning up the mic gain without any regard to what they are really trying to accomplish. The AM freqs are full of them. One would think that enough info has been out on the net and enough people have gripped it by now. Apparently, they just haven't.
Otherwise, having an open clarifier and access to the freeband (which is SSB above ch 40) will be useless, as other stations will have a difficult time understanding you if the SSB modulation is all foxxed up.
Few people who do the NPC mod operate or adjust it correctly. As adjusting the driver current to render the best scope reading is essential for success. Not to mention, adjusting the AM modulation level so that the waveform stays symmetrical - is also just as important for overall success. There are simply too many people just swapping out parts and just turning up the mic gain without any regard to what they are really trying to accomplish. The AM freqs are full of them. One would think that enough info has been out on the net and enough people have gripped it by now. Apparently, they just haven't.
Otherwise, having an open clarifier and access to the freeband (which is SSB above ch 40) will be useless, as other stations will have a difficult time understanding you if the SSB modulation is all foxxed up.
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limiter is there r264 not touched it has only one 1969 final I would like to add another one or go fet I saw on cbtricks how to do the dual fet but would it be better to go fet or go dual 1969's yes I would like more info on the npc mod thank you.
here is a link to the mod for the 959 galaxy which is the same board as the 696 ranger radio.
RF Intensive Study Group • View topic - NPC/RC Modification for 6900xxx Style Boards
RF Intensive Study Group • View topic - NPC/RC Modification for 6900xxx Style Boards
I have tried the dual final mod and replaced every part in the final area even to match the dual finals radio and it would never do the same out out as a factory dual final. for the time and cost I do not feel it is worth the effort.
some one else here may feel it is worth it but I do not. best I ever got out of it was 25 watts peak. the single final does about the same, just a little less.
To be honest I had the exact same radio. Complete tune and alignment, audio mod for AM, receive mod, and a Viagra board for 120 channels. The SSB drift was so bad I had to keep wondering if it was a Galaxy radio. I ended up moving it down the road for a 40 dollar loss.
All that said this would not be the radio I dumped alot of money into by doing worthless dual final mods and such. It is what it is, give it a basic tune and alignment and if you need MOPOWA add an amplifier.
All that said this would not be the radio I dumped alot of money into by doing worthless dual final mods and such. It is what it is, give it a basic tune and alignment and if you need MOPOWA add an amplifier.
Had one of these radios too. Just sold it a couple of months ago. Not a bad radio at all. No Viagra board; just the P5/P6 mod. Also did the Schottky mod. Was very stable even with the clarifier mod I did on it that I got from ExitThirteen (thanks dude; it worked out great!!!). Radio peaked up very well.
The clarifier mod is pretty simple. First you must do the standard clarifier mod which means you clip two diodes and add a jumper wire to get +8v for RX and TX. Then you just jump R114 and retune the Loop Mixer cans. Slides 3kc to the right and 11kc to the left. Stable mod and far better than adding a 5.6uh choke to the veractor diode. Very stable! Thanks, Exit!
Since then I have also worked on a couple of these radios for some locals; they turned out very nice.
Same chassis as the Galaxy DX-959
The clarifier mod is pretty simple. First you must do the standard clarifier mod which means you clip two diodes and add a jumper wire to get +8v for RX and TX. Then you just jump R114 and retune the Loop Mixer cans. Slides 3kc to the right and 11kc to the left. Stable mod and far better than adding a 5.6uh choke to the veractor diode. Very stable! Thanks, Exit!
Since then I have also worked on a couple of these radios for some locals; they turned out very nice.
Same chassis as the Galaxy DX-959
I have the 696 and 959 myself and both seem to work nice. the best increase I found on them was changing a couple caps in the mic circuit. these are choked off for cb use. changed the caps to be like the export radios and the audio and swing came up nice.
change C171 and C235 which are 0.047uf stock, go to 0.1uf on both to make them as the export radios. will increase mod and swing on the 595 and 696 radios.
change C171 and C235 which are 0.047uf stock, go to 0.1uf on both to make them as the export radios. will increase mod and swing on the 595 and 696 radios.
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The one I had was bought from Doug at Custom CB Radio, this was back when they had that X-Mas sale for 89 or 99 dollars. Doug did all the work except the Viagra board, Jim at Key CB added that.
Great AM talker, very punchy on AM, sounded kinda tiney on SSB and the clarifier just would not settle down. I have no doubt that the work was all done up right, two very good techs. For mobile use in a winter weather area it was just a drifter.
Great AM talker, very punchy on AM, sounded kinda tiney on SSB and the clarifier just would not settle down. I have no doubt that the work was all done up right, two very good techs. For mobile use in a winter weather area it was just a drifter.
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