C-Hamm for most Hammarlund radios.
for HQ-105 use HQ-100
*Does not work on 6 Meter band |
It is easy and stable since For those models that are dual DFD1-Hammarlund uses a 20 MHz Jumper selectable 10Hz/100Hz Digital filtering to eliminate flicker |
TWEAK MODE
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 +/- 1.28KHz in 10 Hz steps for 455 KHz Ifs and +/- 12.8KHz in 100 Hz steps for the 3 MHz IFs.
Top jumper decides 10Hz (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.
A universal interface for tube type radios (Included FREE)
Additional applications may be found at:
www.aade.com/applications2/app2.html
(shipping is included in shopping cart value) |
|
|
|
|
C-Hamm plug-n-play
|
$150.00 |
|
|
|
