Fw: [R-390] R-390A ....more AGC

[email protected] [email protected]
Sat, 22 Feb 2003 15:20:39 -0600


>I still have a problem with the carrier meter repeatability, crank
>the RF gain down and back up and you get a completely different 
>reading. Zeroing the meter varies also ...it's OK for a while, then
>it's off again. Anyone experience that ? 

Turns out that the meter is "sticky" put another uA meter in parallel 
and if you slowly turn the adjustment potentiometer up until the other 
meter reads "x", the carrier meter reads "20". If you turn the pot to 
full scale and slowly turn the pot down until the other meter reads
"x" again, the carrier meter reads "60". I took the meter apart (fun 
job) ....that ring with the 4 indentations is NOT threaded into the 
housing, its just a pressed in soft metal ring. I drilled through one 
of the indentations and pried the ring out. Will JB Weld it back. 
Also you can now clean the glass ...I don't know how a sealed
meter gets junk on the inside of the glass.

The carrier meter "zero adjust" is basically non functional, so I 
loosened one of the movement end screws a 1/4 turn and the meter 
now moves freely and the "zero adjust" works. Easier to tune up 
stuff on the R-390 if the carrier meter works. 

73  Kees K5BCQ