Power for the
dial is from the 6.3VAC filament supply, or 9 to 12VDC can also be used.
The power cable
has a red and a black alligator clip. To connect to the 6.3VAC
supply without soldering, the insulation on one of the wires going to
the receiver’s dial lamps can be removed just enough to allow the red
alligator clip to be attached. The black clip should be grounded.
A better way is
to remove the alligator clips, route the cable under the chassis,
locate a 6.3VAC source, and make a solder connection. The wire
with the stripe is the power wire. Ground the wire without the
CAUTION, REVERSING THE CONNECTIONS WILL
SHORT THE 6.3 VOLT SUPPLY AND WILL DAMAGE THE RECEIVER.
potentiometer R7 (BLUE DOT) until the dial reads your model number,
then turn it a little more. If you using the dial on a single
conversion receiver other than Hammarlund, adjust R7 until the dial
CONNECTING TO THE VFO
Two methods for connecting to the VFO are described below.
Method 1 is the best if it works over the desired frequency
range. It is easy and does not pull the oscillator. Method
2 is also easy but it does pull the oscillator a little.
To connect to the VFO without soldering you will use the small
interface circuit and tube shield assembly included with the
DD-101H/U. Position D of the 4 position switch on the counter
must be ON.
Remove the tube shield from V2, the oscillator tube, and replace it
with the shield and interface circuit assembly. Don't push it all the
way down. It must not
to the chassis. Clip the BLACK wire to ground. Now plug one
end of the gray cable into the interface circuit and the other end into
the black RCA jack on the electronics board. The extra cable
length is not important. Turn the level control R4 to maximum and
check if the display is counting over the desired range. If it is
working over the desired range, this is the best method to use.
The RED wire is not needed with this method and can be cut off.
Remove the interface circuit from the tube shield. There is a loop of
green wire on the interface circuit board. Cut the loop at the
top. Now twist the green wires together one half turn to form a
very small capacitor (called a gimmick). Clip the RED alligator
clip to the stationary plates of the oscillator section of the
bandspread tuning gang capacitor. It is usually the section
nearest the front panel. Clip the BLACK one on the frame of the
tuning gang. Adjust the input level control, R4, to maximum, and
check if the dial is counting. If it is not counting or
is not counting over the desired frequency range, twist the wires
another half turn. Continue this procedure one half turn at a
time until the dial is counting over the desired range. Don’t
twist them more than necessary. Insulate the interface board
after the final adjustment so it doesn’t short to the chassis.
NOTE: When a
connection is made to the oscillator it will have the effect of
lowering, by a small amount, the maximum frequency that can be tuned on
each band. It is a problem only if a frequency that you want is
at the extreme high end of the band. The problem can be corrected
by realigning the high frequency trimmer for that band with the dial
connected, or tuning the frequency on the low end of the next band.
IS THE TCXO CALIBRATION AND HAS BEEN SET AT THE FACTORY.
IS THE DISPLAY CONTRAST AND HAS BEEN SET AT THE FACTORY.
OFF = 100Hz Resolution ON = 1KHz Resolution
Turn ON To Select The TWEAK MODE To Calibrate For Accuracy
Turn ON If You Are Using The High Impedance Interface Circuit
The tweak mode
is used to calibrate for inaccuracy of your receiver’s IF
frequency, or for setting the IF to a nonstandard frequency. The
frequency can be adjusted to 455KHz + or - 12.8KHz. Unless you
require extreme accuracy, this adjustment
will probably not be necessary. There is a High and a Low
adjustment. If your receiver is a single conversion, the
Low control is the only adjustment that applies. The High
adjustment is for double and some triple conversion models.
receiver on a known frequency below 7MHz. An AM broadcast station
will work on general coverage receivers. Now adjust the Low
adjustment, R5 (GREEN DOT) for the correct reading on the
DD-101H. Do this on all receivers.
If your receiver
is double or triple conversion, repeat the above procedure using WWV on
or 20MHz and adjust the High adjustment, R6 (RED DOT).
usually automatic. I your frequency readout is not correct on the
high bands, switch the rear mounted switch to the opposite position.