DFD2 is designed to display the carrier frequency for units consisting of a crystal (or phase-locked) controlled converter in front of a tunable IF such as the Collins S line, KWS-1, Yeasu FT101, Heathkit SB301, Yaesu FT301 and Kenwood TS520. It measures the HFO (crystal oscillator), the VFO (tunable oscillator) and optionally the BFO. It then computes the RF frequency as RF=HFO +/- VFO +/- BFO. If BFO is zero it computes RF = HFO +/- VFO +/- IF where IF can be adjusted from 0 to 16MHz, in 1KHz increments, by the offset trimpots.
Custom units are available for particular model radios.Collins S line, 75A4,KWS-1,R-390/A, Yaesu FT101, Heathkit SB series, HW-101, and Kenwood TS520S/SE.
DFD2 displays the exact carrier frequency of the signal. When someone says "meet me on 14.225.150MHz USB" you'll be right on frequency.
DFD2 has 100Hz resolution. Custom DFD2s are jumper programmable for either 10Hz resolution or 100Hz resolution.
When BFO is more than 1 KHz greater than IF it displays LSB (lower sideband). When BFO is more than 1 KHz less than IF it displays USB (upper sideband). When BFO is less than 1 KHz from IF it displays CW.
When BFO is zero, as for AM and FM, or when not used no mode is displayed. When BFO is zero custom units display AM mode.
This automatic mode display from BFO frequency does not work for some units, particularily the FT-101 and SB-301 which use the same BFO frequency for CW and USB. A custom unit for the FT-101 and SB-301 displays CW/USB for that BFO frequency.
DFD2 is for the more technically inclined since it is often necessary to modify the radio to bring out the signals. The VFO is usually available but the HFO and BFO may not be. Notable exceptions are the Collins 75S-1, TS-520SE and Heathkit SB-301 which have these signals brought out to RCA jacks on the rear panel. DFD2 is essentially PLUG&PLAY for those units.
The advantage of DFD2 is that the accuracy of the frequency displayed is dependent only on the accuracy of DFD2's reference oscillator which you can set. Setting it for any one frequency sets it for all frequencies. Errors in the frequency of the HFO crystals are accounted for in the measurements. A good HFO crystal might have an accuracy of 50 parts per million which can be 1500Hz for a 30MHz crystal. DFD2 provides the maximum accuracy of operating frequency.
Custom microcontrollers are available for the FT-101, Collins S line, Heathkit SB-301 and TS-520 at no extra charge. If you have a fairly common rig of this type design for which I do not have a custom microcontroller as yet, send me e-mail and we will work togather to develop one.
PRICE 49.95 + any options you order as listed below.
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By Mail Almost All Digital Electronics, 1412 Elm St. S.E., Auburn, WA 98092
Same physical size as DFD
LED Backlit Display module also available.
This module is the same size as the non-backlit module and replaces it directly. You will have to supply a dropping resistor to set the current from your primary power source. The forward voltage drop of the LEDs is 4V and the maximum current is 200ma. The unit lites up pretty good with 30ma. At this setting it can be powered continuously from the on-board 5V regulator through a 33ohm 1/4 watt resistor. From 12V you need an 80ohm/2W resistor for 100ma, or a 160ohm/1W resistor for 50ma.
For LED backlit module
instead of regular module add $7.50
BIGGY lcd display module option
L/C Meter IIB you will love this one.
DFD1 for single conversion and direct conversion
DFD3 multi use user programmable unit (auto-programs itself for many radios)
DFD4 0-3GHz (build a bench-top frequency counter for about $70)
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