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Discussion in 'General CB Services Discussion' started by DIRTY HARRY, Feb 11, 2008.
ABOUT 7.3 VOLTS, I DID TRY INCREASING IT TO 8.5V BUT IT DID'NT MAKE MUCH DIFFERENCE WITH THE SWING,I EVEN TRIED THE TRICK WITH PUTTING A RF CHOKE INLINE WITH THE VARACTOR DIODE, WHICH I THINK IS D31 & THAT ALSO DID NOT WORK, IM WONDERING IF SOME OTHER COMPONANTS ARE SUPPOSED TO BE REMOVED LIKE THE SLIDE MOD FOR THE STALKER XX HOMEBASE? EXCEPT THEY ARE TOTALLY DIFFERENT PCB BOARDS..
to mod clarifier:
There should be an orange wire going from the clarifier pot to R168 on the PC board. Remove this wire from the PC board and connect it to the cathode of D44 (7.5 constant volts)
There is a resistor (R231, 6.8K ohms) going from the violet wire to PC board ground. this value can be lowered to get more slide, and some people just replace it with a jumper, but to protect the power supply; a diode should be used instead.
you can also increase the B+ voltage to the clarifier to increase slide.
after doing these mods, you can try adding about 5.6uH to the varactor diode (D31). or you can try replacing it with an NTE612, 613, or 614.
they are supposed to be the closest thing we have to a super diode, but i have had mixed results (mostly bad) in using them.
VR11 AM power
VR3 FM deviation
here is a link to a good schematic:
does this also work for broadbanding the VCO's on the MB8719 radios?
(cut trace to pin 6 of VCO and add "super diode")
thanks for any info you have on this,
d44 has 1.62 volts d.c constant.
Hi freecell,not cheap to buy the mv1404 in the u.k & how much slide would this give me??? cheers again
it is a 7.5 volt zener diode according to the schematic.
are you sure you measured on the right side of the diode?
it looks like there is 8 volts constant available at the junction between R56 (1K) and VR2.
i have never had one of these radios; this info is out of an old book.
im sure you can find a constant 8 volt source by tracing around the radio with the schematic if that one doesnt work.
either way it's the one to use.
says he uses the SVC251 or the BB809 for these kinds of things.
are they the same as an MV1404?