POWER
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 strip.

CAUTION, REVERSING THE CONNECTIONS WILL SHORT THE 6.3 VOLT SUPPLY AND WILL DAMAGE THE RECEIVER.

PROGRAMMING
Adjust 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 reads “FREQ”.

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 board must be ON.

Method 1)    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 ground 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.


Method 2)    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.

R3 IS THE TCXO CALIBRATION AND HAS BEEN SET AT THE FACTORY.
R10 IS THE DISPLAY CONTRAST AND HAS BEEN SET AT THE FACTORY.

SWITCH OPTIONS
S1-A    OFF = 100Hz Resolution    ON = 1KHz Resolution
S1-B    Turn ON To Select The TWEAK MODE To Calibrate For Accuracy
S1-C    Not Used
S1-D    Turn ON If You Are Using The High Impedance Interface Circuit

TWEAK MODE
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.

LOW ADJUST
Peak the 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.

HIGH ADJUST
If your receiver is double or triple conversion, repeat the above procedure using WWV on 10, 15, or 20MHz and adjust the High adjustment, R6 (RED DOT).

OPERATION
Operation is usually automatic.  I your frequency readout is not correct on the high bands, switch the rear mounted switch to the opposite position.