![cre 8900 mic wiring diagram cre 8900 mic wiring diagram](https://i.ytimg.com/vi/GRs7ebIk0tQ/maxresdefault.jpg)
- Cre 8900 mic wiring diagram install#
- Cre 8900 mic wiring diagram mod#
- Cre 8900 mic wiring diagram update#
- Cre 8900 mic wiring diagram mods#
- Cre 8900 mic wiring diagram plus#
Tweak L20 and L17 for best PEP when modulated. Gently spread L13 and L12 and tweak the spreads for best PEP when modulated. Remove R55 amd solder a 22pf cap in its place.
Cre 8900 mic wiring diagram install#
Remove R56 and in its place install a 470-ohm resistor in series with a common switching diode (1n914 or similar), with the banded end of the diode towards the front of the radio. MOSFET Supertune (29LTD classic and newer): Replace stock final with IRF520 MOSFET transistor (pin-for-pin match when installing). MAKE SURE to use heat-sink compound (a very light coating is sufficient) when mounting the new final, and MAKE SURE the final mount screw is tight! Spread Open L12 a tiny bit, and adjust L16 for best swing, using a loud, steady "aaaaaaah" sound into the mic (or if you have a function generator, set it up for 1khz at about 16mv output, and use that. If TR18 has been removed or cut, replace with a 2SA733. D11 is a simple small-signal swithcing diode like a 1n147, and C3 is just a 1uf electrolytic. If D11 or C3 have been removed, replace them. Set VR4 just a bit to the right of half-way open. Replace R 55 with a 10-15k resistor, and solder a 33-55 pf cap across that resistor. Solder a 68pf cap across C59 if there is already a 33pf across it. Solder a jumper across D8 (this may cause receive distortion at high volumes, remove jumper if it does). Supertune: Replace the stock final with a 2SC1969 unit.
Cre 8900 mic wiring diagram mod#
Use CARE when soldering to the PLL chip! If desired, this mod may be wired through a switch. The smaller the value, the more the receive is boosted. Install a 22k-220k ohm resistor between these two points. Receive Boost: Locate pin 14 of the PLL chip, and the Positive (+) side of C-12. You can also try removing R125 and increasing the value of R102. For AMC changes, place 5k variable resistor from base of TR33 to ground. RemoveC119, and run a 1000uf cap from negative side of C119's position to the base of TR34, with the positive side of the 1000uf cap going to the base of TR34.
Cre 8900 mic wiring diagram mods#
However, there are a few mods that will yield better over-all PEP and still keep decent quality sound. I have found that the best over-all sound and performance comes with nothing more than a standard tune-up, with the AMC circuit left intact.
![cre 8900 mic wiring diagram cre 8900 mic wiring diagram](https://m.media-amazon.com/images/I/61EqHQeRETL._AC_SX450_.jpg)
I do not recommend extensively modifying the 140/142, due to the type of modulation circuit used. Supertune: Many of you have asked about supertunes for these radio. You may need to re-align the frequencies a bit. Wire a switch from Pin 10 to ground(SW-2 on the chart), and another from pin 11 to pin 12 (SW-1 on chart).
![cre 8900 mic wiring diagram cre 8900 mic wiring diagram](https://www.aes.org/images/e-lib/thumbnails/1/9/19151_full.png)
Isolate pin 10 from ground (Cut the trace). Locate the MB8719 chip (usually right behind the channel selector). Reset the AMC level for 100% modulation.Įxtra Channels: Replace the 11.1125 mhz crystal with a 11.3258 crystal. RemoveC174, and run a 1000uf cap from negative side of C174's position to the base of TR41, with the positive side of the 1000uf cap going to the base of TR41.
![cre 8900 mic wiring diagram cre 8900 mic wiring diagram](https://www.worldwidedx.com/proxy.php?image=http%3A%2F%2Fblog-imgs-42.fc2.com%2Fh%2Fa%2Fr%2Fhardtrance303%2Fcre8900mic2.jpg)
I have found that the best over-all sound and performance comes with nothing more than a standard tune-up, with the mod level set for 100%. I do not recommend modifying the 148 very much, due to the type of modulation circuit used. Supertune: Many of you have asked about supertunes for this radio. Wire a single-pole, single-throw switch from pin 10 to ground (SW-2 on chart), and another from pin 11 to pin 12 (SW-1 on chart). For safest operation, do not jumper any diodes.Įxtra Channels: Locate the MB8719 chip (usually right behind the channel selector). This does increase the output by a small amount, but it also causes a risk of extreme receive distortion when receiving high signal levels at high volumes, as well as a slight risk of component damage in the event of an overly-high inductive kickback voltage spike. Note: Some tips mention jumpering a diode with a piece of wire. They are the result of my own experience and research. Note: These are NOT copied from any other source.
Cre 8900 mic wiring diagram update#
Watch for new content as I get time to update this page.
Cre 8900 mic wiring diagram plus#
Most of these will be categorized by radio brand and model, plus a category for miscellaneous tips.