[Hallicrafters] SR-150 RIT Adjustment

[Sandy, W5TVW]

The RIT controls and the "CAL" control does esentially the same function.
I assume you have checked the VFO alignment with the "CAL" control in
the center of its range?  If it zeroes off to one side or near the end of the 
rotation stops, the RIT   control will do the same thing.  The CAL and 
RIT controls both vary the bias on a varactor diode CR4 which shifts the VFO
frequency appropriately in receive or transmit mode., switching done by
relay K1.  The CAL pot. R80 should swing the VFO thru the same range
as the RIT control R82 if things are working and aligned properly.
The small JAICO relays in the SR-150 are impossible to find.  I subbed
some reed relays which fit into the space available and worked very nicely.
The T/R relay arrangement in the SR series is sort of oddball in that K2
and K3 are actuated with the potential across the cathode resistor of the
AF output stage V13.  These are keyed by  relay K1 which is in turn keyed
by V19B.  Sort of a round about way of doing things.
I have the modification information for replacing relays K2, K3 for those
who might have SR-150's with these needing changing.
73,
Sandy W5TVW