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> Digital dial for most hammarlund radios.
Digital dial for most hammarlund radios.
C-Hamm for most Hammarlund radios.
* HQ-110* IF=455KHz/3.045MHz
* HQ-145 IF=455KHz/3.035MHz
* HQ-160 IF=455KHz/3.035MHz
* HQ-170* IF=455KHz/3.035MHz
* HQ-180 IF=455KHz/3.035MHz
* SP-600* IF=455KHz/3.955MHz
*Does not work on 6 Meter band
You simply adjust a 15 turn trimpot
until the model of your radio is
No other adjustments required.
there is nearly a full turn of the pot
For those models that are dual
detects the band and changes the
IF offset. It has no controls.
Jumper selectable 100Hz/1000Hz
Digital filtering to eliminate flicker
provides optional accurate calibration capability.
The frequency (F) to which the radio is tuned is computed as F = Local Oscillator freq +/- IF freq
C-Hamm assumes the IF frequencies shown in the chart above are the actual IF frequencies of your radio.
However, 455KHz Ifs can be aligned to some other frequency and some types use a crystal filter or
crystal controlled second conversion which make the actual IF frequency a function of the frequency of those crystals which can vary a few hundred Hz from radio to radio.
A jumper on the PC board enables TWEAK mode. In TWEAK mode there are 15 turn trimpots which allows adjustment of the IF frequency +/- 12.8KHz in 100 Hz steps.
Top jumper decides 100Hz (off) / 100Hz (on) resolution
Bottom jumper decides tweak mode (on) / (off)
For dual conversion radios there is a separate TWEAK control for each IF frequency.
To adjust TWEAK mode, tune a known frequency (crystal calibrator etc.) for maximum
signal and adjust TWEAK control to cause correct frequency to be displayed on DFD.
C-Hamm assumes that the LO frequency is always greater than the received frequency so it subtracts the IF frequency.
This is not always true so a switch is provided on the rear panel that causes it to add the IF frequency.
If the displayed frequency appears to be in error by twice the IF frequency (ie: 910KHz for a 455KHz IF) then the switch is in the wrong position.
Check out the universal interface for tube type radios (Included).
Basically you simply slip a tube shield over the oscillator tube, usually a 6C4,
clip the power alligator to the dial light socket and
connect the supplied cable to the C-Hamm.
This is the recommended, and easiest to do option. Next best thing to plug-n-play.
Additional applications may be found at:
/applications2/app2.html
