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The President Bill FCC (AM) and President Bill ASC (AM/FM) are two different models, I don't know how much actually differs between the two, but yeah I figure I'd add this to the thread. As far as I know, the schematic and or factory service manual have not been released. I haven't looked for...

I guess the link to that document wasn't easy enough to find in my original post..

Fair enough, why add more parts than necessary! (y) I've been specifically playing with AM only radios that came with BJT final transistors, and adding the MosFet and bias circuitry, and I agree I see no reason to over complicate things. The adjustability of the regulator is very "smooth" IMHO...

I found this on Google; And apparently the new and old PLL function the same? (early 2000's to 2015?) http://downloads.cobra.com/CB/TSB/TSB10085.pdf I don't know if the datasheets are easily found. Edit: I also found this but I don't know if it is very relevant to what you're doing.. ~All...

Good morning y'all! :coffee: To reiterate, if i use a regulator, I should have a (large value) discharge resistor to ground, like 20K or higher? :oops:

The voltage goes to about 0 during receive at the point where I grab it. 8 Volts during TX, this spot would be a good place to connect hard key circuit relay, and feed a jack on the rear of the radio, for those candle boxes i'm fond of. :) (thanks for the idea Tallman!)

No worries, good luck with it.

Tallman, any concerns with the gate voltage being present all the time? I like to switch the bias voltage on for transmit only.

Have you just got this radio recently? If so, I'd have a look at this area: I had a Grant that had a super diode and choke added, and it was one channel off as you describe, I can't remember if the crystal frequency was changed also.. A "super diode" may appear to be factory, but the one I...

That is a fair question, it doesn't take much current. Of course it will dissipate more heat the higher the input voltage. The reason I can say that it doesn't take much current without giving you an actual measurement, is because I've gone down the lazy path on some of my personal projects...

I sometimes just use a regulated bias supply (w/ a choke) with an adjustable voltage regulator, and circumvent the whole "companion component", the voltage present at the "Gate" pin turns on the device. As Andy pointed out, a variable resistor offers the advantage of adjustability, but you'd...

Yeah, I would if I was trying to make my own EKL EN-369. (y) EDIT: Look for less than 4 volts @ the Gate pin when it is all said and done, closer to 3.7 Volts would be better.

VGs on voltage is listed in the datasheet for the device, usually 3.5-3.7 Volts at the Gate pin is okay for most of the common devices used, IRF520, ERF2030, FQP13N10..

I believe 6.3 V was a common filament voltage, time to hit the parts bin!

(y):ROFLMAO: & three out of five times it was likely an "operator error", not every radio is "fool proofed". Add a "power mic" and enough echo, and you can just about overdrive anything, hell even a "stock radio" can sound bad if the user operates in a reckless way (overdriving the audio input).

No winter field day for me. I'm loving the sunshine state.

Enjoy your experimentation also.. I don't "sling solder" until I've had my morning coffee, cheers! & Kind Regards PS this thread has served its purpose. PM's work great for shout-outs too. Edit: the PC-122XL modulator is not setup like the 148, compare the schematics. Look where the audio...

I've played around with & without the 220 Ohm from emitter to collector, I should try 390 Ohm just to see if I observe any changes in the way it operates. The regulator runs cooler with the resistor. It seems (I'm bad at recording data at home) I had more average power with the resistor, but...

Cool, I didn't know that a copy was floating around of his early build. Yeah I never got an opportunity to join the CB Tricks forum, so I don't know anything about the discussions that took place there. The modulator more closely resembles what is found in the Grant XL/Cobra 148 GTL, looking...

Okay no worries, I must've misread or misunderstood something.