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President Richard stock mic substitute

Well fellas the road devil arrived so I rewired it 6 pin for the president and think it's superior to any dynamic mic I've tried. On a receiver radio I have set up across the shack I tested it with several other mics and it seems promising with a better feel than the stock. The mic has a much cheaper build quality than ones I've owned years ago but what can I do right.. I modified the gain control by cutting it shorter then sanding it down then a little heat to keep it looking stock. Why did I cut it shorter? Well in a truck installation and hanging from a gearkeeper, there would be too many times I could accidentally move the control so I've eliminated that. It's still accessible, you just have to use your fingernail to move it. Now on to the gearkeeper. Well I built a a small device from a firestik replacement microphone button, an aluminum piece of strap and the gearkeeper D-ring. It'll go into testing tomorrow but I've attached some pics for now.
 

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Reactions: tecnicoloco, Handy Andy, Slowmover and 2 others
@Eldorado828 - Welcome back from the Trip!

Sounds like a Gosh Darn Good Idea...
upload_2020-3-23_7-37-41.png​

I too went on one, and came back better informed about your radio...

We lost Smokin' Joe - but he left behind some good clues - I'll PM you some concepts.

Let me know when you have time...
 
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Thank you gents, I get to daydreaming behind the windshield and once back home I put the daydream into action. Sometimes it's good and sometimes not so much, I've ruined things before putting daydream to reality ha. With everything going on in these strange times, work has almost put on the brakes compared to the barely keep up busyness we were at. After a surprise meeting Friday it looks like I'll be home more, less equipment deliveries, stocks are down, you guys know how it goes... but I have a job for now. 15 years for the same company so I've seen this before and made the cut last time(2008). One day at a time though. I'll look at the bright side, the family is healthy, more time with my family, and more time to put the "daydream" to reality.

Andy, yes unfortunately we lost another of the tech greats....
I appreciate it sir and would love to see what you've uncovered in your search.

I have to say, the little radio is loaded with really nice features, looks sharp, has a great build but the transmit performance has not been impressive at all.

After an email to president I was able to get into the service menu and turn up the amplitude modulation but even after that the limiter circuit is super heavy..

As some would say, it's a real turd on transmit
 
The mod is what @NZ8N was talking about - but one thing we all missed...

Recognize this...schematically...
upload_2020-3-23_15-46-58.png
The Red circled item is the "lag resistor"

The Richard has something similar...​

upload_2020-3-23_15-43-21.png

It's located here...
Blue Arrow...
Eldorado838RichardMod.jpg
​
It was a throwback to the old days - in the Grant and 148's there was a 1Meg resistor used in the Limiter circuit that helped (if that is the word) keep the Limiter from staying on all the time. But it worked In a coupling stage area that was NPN to PNP - so you really just couldn't tailor R127 to meet the needs of how Hot or Cold the limiter was...R131 is what others usually took out to affect on AM side, R127 affected both SSB and AM limiter actions.

R339 is a 1Meg, a 105 on the chip itself...that is the main one you have to change to obtain better gain and AMC action.

The problems are

D300 - you can't remove it, but NZ8N's dropping resistor - is needed right where it stands - but - you have the power flow arriving from the Stage just ahead of the Limiter - which can put a lot of current thru the part and with the shunt installed at the limiter - it can fail and you may or may not be able to talk again because the limiter got cooked at the same time. That was one of the main quirks about the repair - we have had only one return but the Boss kept us in the loop and warned us about the Q313 Solder Blob problem as he called it.

So to reduce that current - if you use the 1K - it will not hold up well - but if you use TWO of them - it will - you use the 1K (just one) at NZ8N mod spot, and place 1K over the top of the 1 Meg resistor (105 R339) just line it right up top of the 1 Meg and tack solder both sides. You don't anything else. You've brought the limiter action down and you even have some limiter action still but allows you to attain 80+ watts (as shown on MFJ meter in Smokin Joe's shop...) if the thing can really attain it.

The D300 is a fail-safe device - one-way valve - but the Q313 and EDIT (308) Q312 (Limiter) clamp so hard - its' for that reason so it (the Fail safe) doesn't engage that fail-safe mode, the radio can go into that mode if it gets too hot or shutdown - but you didn't hear this from me ok? I get yelled at otherwise...
 
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In the 148/Grant, I put a 22k in parallel with C109 (sample and hold), to cause it to release faster, bleeding off the voltage difference. I do not see anything like that in the Richard.

If you follow Q309 back to the Mic amp circuit, you will see that this path limits the positive peaks, where the path to Q110 from the Modulator, this limits the negative peaks.
 
Last edited:
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Handy Andy said:
The mod is what @NZ8N was talking about - but one thing we all missed...

Recognize this...schematically...
View attachment 35589
The Red circled item is the "lag resistor"

The Richard has something similar...​

View attachment 35588

It's located here...
Blue Arrow...
View attachment 35592
​
It was a throwback to the old days - in the Grant and 148's there was a 1Meg resistor used in the Limiter circuit that helped (if that is the word) keep the Limiter from staying on all the time. But it worked In a coupling stage area that was NPN to PNP - so you really just couldn't tailor R127 to meet the needs of how Hot or Cold the limiter was...R131 is what others usually took out to affect on AM side, R127 affected both SSB and AM limiter actions.

R339 is a 1Meg, a 105 on the chip itself...that is the main one you have to change to obtain better gain and AMC action.

The problems are

D300 - you can't remove it, but NZ8N's dropping resistor - is needed right where it stands - but - you have the power flow arriving from the Stage just ahead of the Limiter - which can put a lot of current thru the part and with the shunt installed at the limiter - it can fail and you may or may not be able to talk again because the limiter got cooked at the same time. That was one of the main quirks about the repair - we have had only one return but the Boss kept us in the loop and warned us about the Q313 Solder Blob problem as he called it.

So to reduce that current - if you use the 1K - it will not hold up well - but if you use TWO of them - it will - you use the 1K (just one) at NZ8N mod spot, and place 1K over the top of the 1 Meg resistor (105 R339) just line it right up top of the 1 Meg and tack solder both sides. You don't anything else. You've brought the limiter action down and you even have some limiter action still but allows you to attain 80+ watts (as shown on MFJ meter in Smokin Joe's shop...) if the thing can really attain it.

The D300 is a fail-safe device - one-way valve - but the Q313 and EDIT (308) Q312 (Limiter) clamp so hard - its' for that reason so it (the Fail safe) doesn't engage that fail-safe mode, the radio can go into that mode if it gets too hot or shutdown - but you didn't hear this from me ok? I get yelled at otherwise...
Click to expand...
I appreciate it Andy, I'll try to jump back into it when I park the truck Friday night because it's back in service until then. The road devil really helped the radio, getting better reports from the other drivers on the audio.
 
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NZ8N said:
In the 148/Grant, I put a 22k in parallel with C109 (sample and hold), to cause it to release faster, bleeding off the voltage difference. I do not see anything like that in the Richard.

If you follow Q309 back to the Mic amp circuit, you will see that this path limits the positive peaks, where the path to Q110 from the Modulator, this limits the negative peaks.
Click to expand...

(y)(y)

There's more to this - but being conservative on the radio work - keeps it in the cab a lot longer.
 
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