I can't tell from your photo, but has the fork just come off the end of
the threaded portion of the drive screw? If that's what you're
referring to, just guide it back on while turning the drive screw.
It's just been driven past the stop, usually because the spring loaded
stop pin has been gunked up with grease and is either slow or not coming
out at all. Once you get it back on the drive screw, you'll have to
press the stop pin back in to get the mechanism back 'inside' the
stops. Then set with a counter for 5.455 and 4.955 MHz at the two
ends. There is a procedure on the CD in the MISC directory. It's for
the TR-4, but the mechanism is the same. I find it easier to do with a
counter, especially outside of the radio!
The PTO is designed to be run from a current limited source. The
internal Zener diode is 10 V, and there may or may not be a small
decoupling resistor in series with the input. I just connect a DC
source and increase it to 10V, note the current, then increase the
voltage for about 10 mA more. You can put a series resistor and
calculate a higher voltage input if you are more comfortable with that.
Get as much grease off of the nylon gears as you can. The metal gears
just need a drop of oil for the anti-backlash action
--
73, Garey - K4OAH
St Charles, IL
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Paul Gerhardt wrote:
OK I got the 'spare' PTO out to test and it has a loose 'tuning shaft'
The tuning shaft is loose from the 'fork' piece. It appears as though
someone had tried to solder it on to the fork piece. Was it orginally
a 'press' fit? Has anyone ever repaired this problem before.
I posted of pix of the Assy on my blog at pgerhardt.blogspot.com . It
is marked as a T4XB unit.
After fixing the shaft to the fork I would like to test it for
operation on the bench. I see a ground wire (green black) and another
wire a red white). There are also two solder lugs one near the white
red wire and another at one of the spring clips. How much voltage
should I put on the PTO to check the oscillator?
There is also some small amount of grease on the gears but it feels
'OK' turning. I will probably just brush off the gears with an old
toothbrush and getting them as dry as possible. Is any thing else
recommended?
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