NorCal 20 double regulator mod trouble


From: Terres Family (
Date: Wed Jun 05 2002 - 22:34:21 CDT

Hi All,

This is a Larry East NorCal 20 mod where he described adding a low dropout
9 volt regulator ahead of the 78L08 using a TK1190 with two 1N914's in
series between its ground lead and the rig ground to make it into a 10 volt
regulator instead of a 9v. This is
suposed to absolutely cure sagging VFO voltage related chirp and also
provide a constant voltage for the AGC independent of varying power suppply
voltages. Looked like a neat mod and i wanted to try it and had ordered the
parts a long time ago.

I am having a little trouble:
I have one of the TO92 sized TK11690 devices and have hooked it up like
Larry said and it puts out abit over 10 volts like its sposed to until i
hook it's output to the line that feeds the 78L08 and then the voltage out
drops to a bit over 0.9 volts. I am kinda stumped.

Confession: now i do have a second TK11690 and have not tried it yet. I did
a beautiful job of hooking up the first one but had the pinout wrong with
the ground lead and the output lead switched (not worth telling).

This did not work and I de-assembled it and all the parts seem ok, and it
makes 9v from 12 and with 2 diodes it makes a little over 10v but when
hooked up to power the 78L08 it makes ~0.9v. So before i put my second
TK11690 in harm's way i figured I would ask you all if i am overlooking
something obvious or perhaps previously discovered.

Thanks for whatever help you can come up with &

jerry aa1of franconia nh

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