Asymod III schooling (snake oil?)

If you use it right the power output from the the radio is lower than factory settings for a cb set and lower than spec for exports. The finals are safe. Cranking up the power to 11 defeats the purpose of installing it because the audio will sound like poo.

The only people that think the voltage of the external power supply is a problem have trouble comprehending high level modulation. From experience I will tell you that one of the opamps on the board will croak long before the final in a cobra 148.

The am regulator on the board will run cooler on a cobra 25/29 with a bipolar final. A lot of ssb rigs run the final in class B in AM mode. The instructions with the asymod tell you how to change it to class C like an AM only rig would be.

711 said:

All of Asymods boards are off MMM's old board. Jose stuffs a cheap Chinese buck converter on top of the board to run off of single radio supply. Jose's knock off works but I've seen his converter board fail often. I've had both MMM's boards and an Asymod. Jose adds a few more parts to dress up his units but they work the same. MMM's buddy Dave designed the circuit , the schematics been floating around. A few parts on the schematic are incorrect but the thing as a whole gets you the idea. To each his own, I like the new MMM board better. NPC and some mods to the darlington gets you close.

Click to expand...

Hello All.. This is Johns buddy Dave mentioned above. I wanted to thank all in here for saying it like it is and being fairly neutral. Usually when this topic pops up it turns into a Ford vs Chevy argument that is not really that useful and I don't want to be involved. I think the technical discussion in here was accurate, unlike some of the wild stuff I see sometimes. As for asymmetry levels, anything over 150% is ridiculous. These circuits are meant to just give a little more punch on the positive peaks, and have a relatively flat passband so that your processing efforts are passed on with fidelity.

The direct injection mods that use NPN Darlington configurations like the 148 can have pretty good sounding audio. Of course the won't have any asymmetry other than what is already in the source material. The direct inject mods with circuits like the modulator on the Galaxy radios do not have a flat passband. There is a transistor in that chain that has a separate gain for DC and AC. This is caused by a capacitor in the emitter circuit that results in higher gain with increasing frequency. Good processing can weed this out, but I just feel better knowing that what I put in is what comes out.

welcome to the forum Tink!

it'll be nice to have some new perspectives on DI radios in general, and i for one am hoping you enjoy this place enough to stick around and tell us about whatever tinkering you are currently doing.

Are you interested in talking about other DI methods that don't necessarily involve external boards being installed in a radio?

If so, we can start another thread on that and im sure there will be lots of questions.
LC

DI isn't just one thing. It's a whole catalog. At one extreme is the MMM-type solution, replacing every part of the radio's transmit audio circuits.

At the other extreme is a jack and a switch to feed external audio into the same mike-gain control that your mike socket feeds into.

In between are setups that feed audio halfway down the audio chain, after the mike amplifier, but before the radio's AM modulator circuit.

The differences are what you're injecting, and where in the radio.

Lotsa differences.

73