President Richard stock mic substitute

[NZ8N]

I am not a proponent of removing or disabling the AMC circuit, as that is the leading reason there is so much hash, trash, splash and bleed over on the air.

'Twere me, I would modify the timing so it releases faster, such as this:

Adding a 4.7k (to 1k) from the base of Q313 to ground (Emitter leg) will (should) increase the release speed and decrease the "hold time" of the circuit.

Adding a resistor between the red circles (trace for the Base of Q313) to the green circle (Ground trace), (if you have a chip resistor), or if you use a non Surface Mount resistor, the red circles on one side of the resistor to any part of the large green trace above that, after scraping the green coating away to expose the copper trace underneath, should do the job.

 

[Eldorado828]

I've never removed a limiter other than for Guinea pigging on any radio and so that's why I'm so hesitant. Now the method you're suggesting looks like what is done on the stryker 94hpc to make those come alive. Never did it on mine but I remember seeing that discussion in a thread here. I feel ignorant asking so many questions but I do so because I'm absolutely ignorant to these modern beasts. Give me a 3600 or 6900 pcb and I'm really familiar but here not so much. It's definitely a learning experience for sure. I'm really appreciative for the knowledge and patience you seasoned gurus have for my questions.

 

[Handy Andy]

... when you said "On these - it may not be as easy - for they did set these up with circuits that "hang up" if they have no place to go - so if you remove a part - that may make matters worse and the radio won't even work at all."

That is what my former boss would say.

And as you look thru the Schematic, there are a few "time bombs" in them - referring to If you do this - You get This.

So I'm cautioning you it is easier to "tack on" a simple resistor than to remove the part - why? They have an epoxy "Seat" to keep the part in place while wave-flow soldered. then they spray a epoxy sealant on the board - that's the shiny stuff to keep it sealed from the factory.

When you try to remove it can scorch the board and you have to repair the pads.

This is the "time bomb" I'm referring to...

See Feature Toggle?
That is driven by Logic setup - so they can control how the part toggles on or off...
IF the VCO ever quit or something, it thinks, has gone astray
- MICMUT engages and kills audio to TX with.

There is more...think back to the days of using R131 approach to the AMC but keeping the ALC working...

But todays version is a little different

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They still use PNP to "invert" the signal used to drive the Limiter.

But how it collects the power to do this - is what I am concerned about...

That "envelope controller" part where when you raise or lower the DC Bias for carrier power - that circuit "follows" the Bias line and applies the drive needed to maintain Limiter control in both ALC and AMC - Note AMC Enable - that is how it selects the Envelope - Off, the AMC follows Envelope - ON? Then the Radio is expecting FM or SSB - no need to use envelope control.

So to me I would NOT do the mod unless you have a pot of 20K and you are able to "tack" solder on the two leads to the board as a means to make a shunt one lead (wiper arm) to that resistor the other lead side to ground then install a 220OHM in series as a current buffer resistor to protect the pot as well as give you a SOLID leg lead to tack on with.- to the 1K part and adjust - pare down the signal drive and observe the results - because if you can reduce the signal drive - you can make the limiter work less on the audio signal.

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You can even use a DVM Test lead tip for the probe leg - just use this setup to locate and verify the Limiter will act on your level - not the OEM full force design.

The Cobra 148 and others - remember those discussions - the Resistor Divider it uses provide the Threshold and Drive level the PNP used to push against the Limiter and the Audio in the Mic Line arriving to the Mic Amp.

In the above Pic graphic, locate the AM MOD Tap and see the diode, but then too - look at the part it's buffered before it arrives to the PNP - a 470 ohm resistor - so it's going to act hard and fast to pull energy from that dropping bias the extra mod does to the AM Mod line. So I'd try to locate that PNP and look for the 471 resistor off it's Base lead and tap that and adjust the Pot to try and drian off power the AM Mod line sends to the Transistor - do the tap between the 471 (470 Ohm) and the BASE lead. Because - they use that 470 ohm resistor to buffer the Base so design your Resistor Divider starting there...


But its in finding the right spot to attach or remove - is what your need to be careful with.

Don't do the mod if you're not comfortable.

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[Slowmover]

The info SimonTheWizard has posted about a German operator with President microphone mods & kits might be worth a look.

Search that site under “Ralf”.

.

 

[Handy Andy]

(So you know...It may be easier to Remove the LIMITER therefore the Mic Mute by removing Q313)

But you didn't hear that from me...

 

[NZ8N]

Rather than REMOVING Q313, why not just short across the Base (red circles) to Emitter(Green circle or Ground), so it is easily restored? This effectively disables the MicMute and AMC circuits rather than removing the transistor all together.

Again, this is why I suggested putting a resistor from Base to ground in this circuit to change it's release time, rather than disabling or removing it.

 

[Handy Andy]

I was referring to those that would rather just eliminate the whole mess altogether...

That why I said what I said...

There have been several returns of this radio chassis due to what we are just talking about.

A lot of current can be shot thru the MICMUT line - it's as if it's a "Self-destruct" feature - design to blow - even if it's shorted - and take out the parts around it much like shrapnel...not physically, but electrically.

How is that done? It's why you have that diode in there - it's a one way valve - and it can easily shoot 8 volts into the Limiter - destroying it too. The "Buffer resistor" it has on that line - is simply there to keep the current down, but in the event of VCO or other failure it sees during a self-test on power up, the MICMUT stays on - prevents any audio. The line is active elsewhere in the radio too.

I've seen this chassis and the Boss cursed it because of it's level of intricacy - He can deal with a Galaxy with a removed limiter - but these just cost too much to repair - to him its' a loss leader.

You're not the first one to do this - I've heard the grumbling of the techs on the bench complaining about these things. The techs hands are tied on the choices they have to make, a choice of removing the limiter even disabling it. Only answer - simply, they can't - they have to submit the radio back to a factory repair site. It's too late for warranty. They also have seen "solder blob shorts" across the very two leads you show...both ways the MICMUT switch amp was affected.

All this boils down to my mess I just quit messing with - Because the Boss is not going to invest in to fixing them and all that extra effort into someone elses misgivings

I was only suggesting a different approach, that being we need to look at AM MOD line and some how develop a resistor divider across the SENSE line to lessen the limiter action. The energy of the limiter action is party from this radios' chassis approach of AM MOD being thrown directly on the line. There is no accommodations for divider networks to soften the action or provide a way out - only thru. There are no true dividers in many of these trigger lines - the techs know this too and it's why they hate radios like these. There's no provision for analog in there like a Divider would provide.

So - no, you are correct in the approach, I'm saying what others will do is not unique, nor does this (suggested) action make it right either.

 

[Eldorado828]

Gentlemen I appreciate all of your help and knowledge but I ran out of time over the weekend doing family things. The covers have to go back on and back in the truck it goes as I need it for the week starting early in the morning. I'll have another week to decide if or which way I'll go to get the president to a more suitable performance. In the meantime I've got an astatic road devil coming so I hope that part at least pans out so I'll report back. Again, I really appreciate you gents sharing your wisdom with an everyday trucker always looking to learn about an evolving hobby I really enjoy

 

[Slowmover]

The previously-mentioned kit also involves physical changes internally to the mic, not just circuitry.

BELLS CB offers the Road Devil wired for the Richard.

Big Kahuna mentions using a multi-channel equalizer with a McKinley to give the radio the punch wanted. (Others also review the product as good). Thread: “Personal Review”.

Yup, just what I need. One more item to Velcro up and then play with while mobile once I order a Lincoln.

Should I add a studio mic on a boom?.

Or just Nitro Knob the hell out of everything, ha!

.

 

[Handy Andy]

There's my initials again - this time, after Nitro Knobs...

Went to visit the site, Found Ralf, and his effort for the Mic handset reminds me of the earlier versions of the Emperor series both the 5010 and 3010 series with the Channel Up/Down.

Ok, so you know where I'm coming from...

it was the Element design that struck me. It would be kinda' cool if that concept got used more often.

The idea on a "stainless steel (or aluminum) doughnut" although not a novelty - it's been done before. But this concept needs to be used more because of the performance "capture" that does for the damping effects as well as the tensile stiffness the cradle provides the element in making the response - as I call it - clearer.

Good call...appreciate the visit.

Sorry, can't help you with your knobs, you'll have to figure that one out yourself...

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[Slowmover]

While at Larry’s CB Shop yesterday I broached this question per President Radios. (He’s got one BIG stack of those).

His off-cuff response was that the Workman 452 was surprisingly long-lived and had a bit of punch. Use Echo, or not.

(Okay, so I added one to my buys. Must be microphone #12 or #13 in my collection). Cheap, too.

 

[Handy Andy]

Recognize that Good Case, but are the Innards like those older Diesel and Workmans...?

 

[Eldorado828]

While at Larry’s CB Shop yesterday I broached this question per President Radios. (He’s got one BIG stack of them). His off-cuff response was that the Workman 452 was surprisingly long-lived and had a bit of punchch. Use Echo, or not. (Okay, so I added one to my buys. Must be microphone #12 or #13 in my collection).

Cheap, too.

View attachment 35300

I've got one myself that I've modified to prevent the squealing they're prone to. It's an ok mic not my favorite and in most cases not really needed with most of today's radios. It crossed my mind for the president but the background noise they pick up won't do well in my application.

Andy, other than the cheaper microphone cord it's still the same workman 452 that they label as superstar.

 

[Slowmover]

Recognize that Good Case, but are the Innards like those older Diesel and Workmans...?[/QUOTE]


9-volt powered
WORKMAN 452
WITH SLIDING ECHO & INDICATOR LAMP

(Pics deleted)

An unloading at a Wally. Can’t really have tiny parts loose as will have to pull away soon.

If further dissection is wanted, say so.

.

 

[Handy Andy]

If further dissection is wanted, say so.

No, you're ok - I have the discrete version - made with real parts...

SMD tends to take the Joy away, but I'm glad to see they still have that thing around.

KEWL!

Thanks!

To all - Happy St. Patrick' Day!
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