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My old friend President Jackson.

sonoma said:
am I looking at the pic of the 477 final without a screw and heat sink grease and a insulator on it.
I just ordered one of these to see how it does. I am going to see if AM can wake up a little by changing a couple resisters.
R258 to a 1.5k
R261 to a 3.9k or 4.7k to see if ether will pick up the modulation.
Click to expand...

Did that for two reasons:

1) To show the output device and identify its make/model. It also shows that it is a 'blue dot'; not a 'green dot'.

2) To remove/replace the old, dried out heat sink compound. This was also done to the other three devices (driver, voltage reg, & audio IC) as they also had dried out compound. The old compound came off as a dry, flaky powder; which cannot provide any heat dissipation.

There is no problem getting more modulation out of this radio. I can get more than 100% out of it with the mod I did to the AM Limiter. The problem is that it will get negative peak distortion after 100% is reached; as any radio will when the AM Limiter has been removed. Removing the limiter is bad because it has a direct bad effect on SSB TX. So keeping the AM Limiter installed -but effectively disabled- by adding the 1.5k ohm resistor keeps SSB TX unmolested. What is needed is to add the compression for the negative peaks so that the positive peaks/amplitude above 100% can be raised up w/o distorting the AM TX.
 
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bob85 said:
if you want to play with the jacko have a look what people do with the lincoln,
its a similar low level mod radio set out differently,
we don't use AM so no need for npc mods, i used to do tx/rx tone mods and filter mods for friends but nothing for AM.
Click to expand...

bob85:
Anything that you can give to describe these mods will be much appreciated. Little info of these Jackos are known of here in the States; and I distrust some of the stuff found on the net. Experience speaks volumes.

Also; what about changing out R258 & R261 values as 'sonoma' mentioned above?
R258 to a 1.5k
R261 to a 3.9k or 4.7k
Click to expand...
http://www.cbtricks.com/radios/president/jackson/graphics/president_jackson_pb-042_sch.pdf

Thanks once again!
 
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Robb said:
Anything that you can give to describe these mods will be much appreciated. Little info of these Jackos are known of here in the States; and I distrust some of the stuff found on the net.
Thanks once again!
Click to expand...



the info I left you on R258 and R261 came from the UK from Rick J. he is very knowledgable on these type radios since they get more of them than we do. I am going to try it when it comes in this week plus I have the mod for the controlled carrier Low Boy was talking about. I just got the part in that was needed to do the mod. I have a old Jackson I am going try it on 1st. just have to get the time to go out and do it.
 
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sonoma said:
the info I left you on R258 and R261 came from the UK from Rick J. he is very knowledgable on these type radios since they get more of them than we do. I am going to try it when it comes in this week plus I have the mod for the controlled carrier Low Boy was talking about. I just got the part in that was needed to do the mod. I have a old Jackson I am going try it on 1st. just have to get the time to go out and do it.
Click to expand...

Links?
 

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