DDS VFO Instructions
Pushbutton Operation
Starting at the rotary encoder, the switches are labeled 1, 2, and 3.
Operation when Listening or QSOing
When the receiver is first turned on 40 Meters will be the displayed band. After the first turn on, the last band/frequency will be saved and loaded on start up. To change bands, hold down Button 3 (right button) and turn the encoder to the band you want. You will be at the start of the band - XX.000
The default digit will be the .01 digit, and tuning will be fairly slow through the band. If you want to scan the band quickly to find signals, push button 2 (middle button) and it will move to the .1 digit for quick tuning through the band.
When you find a signal you wish to tune in, push button 3 (right button) to move the cursor to the .01 digit and you can tune in the signal precisely.
If you wish to transmit on this frequency, push button 2 (middle button), or push the mechanical encoder knob (the switch on the encoder is attached to push button 2), and tap your key. You will see that the Band number will now be displayed on the bottom line of the display and will show your Transmit frequency. Your transmit frequency will remain the same until you hit Button 2 (or encoder switch) and hit your key at a different frequency.
Once your transmit frequency is set, you have RIT and can move your receive frequency anywhere you like - transmit frequency will remain the same.
When you set your Transmit frequency, Rcvr will remain on the display. When you transmit, Xmtr will show on the display and the transmit frequency, even when returning to receive, until the encoder is moved to a different receive frequency. The receive frequency will remain the same even though the transmit frequency will be shown during the QSO, unless you RIT and the new receive frequency will be shown until you transmit again.
If you finish your CQ or QSO and move to a different frequency and transmit without setting the new frequency first, your old transmit frequency will show on the display. Push Button 2 (or encoder switch) or move the encoder slightly to go back to the new frequency, then push Button 2 (or encoder switch) and tap your key to set the new transmit frequency.
PB1
PB1 is used for the transmit function. When grounded, it removes the offset and outputs the correct frequency used for transmitting. The change to transmit frequency and changing back to the receive frequency with the offset is very fast. Up to 40 wpm has been no problem.
Used with PB2 to set Transmit Frequency
Pressing PB2 (or encoder switch) and PB1 at the same time sets the transmit frequency. After setting the transmit frequency, you are free to turn the Rotary Encoder to any receive frequency you desire. For working DX up1, you move the frequency up one 1kHz, set the transmit frequency and then move back to the DX station frequency. See PB2 for more information. PB2 is connected to the mechanical encoder push switch.
PB2
Cursor to Left
Momentary depression moves cursor to the left one decade position. The cursor will wrap from highest decade to 1 Hz decade. Holding down for one second will start automatic movement of cursor to left every 1/8 second.
Transmit Function
When you transmit, the Transmit Frequency and Xmtr will remain on the display. The receive frequency will stay the same. If you move the Rotary Encoder, the Receive Frequency and Rcvr will be displayed and changed to the new frequency displayed.
Set Transmit Frequency
PB1 is connected to your key. You press PB2 (or encoder switch) and hit the key, the transmit frequency is set to the frequency on the display.
The transmit frequency will not be transmitted or displayed when you set it. If you want to check the transmit frequency, send one dot (will be transmitted) and Xmtr with the transmit frequency will be displayed. You can move the receive frequency as desired (for RIT function); the transmit frequency will remain the same.
If you finish your QSO and move to another one at a different frequency, remember to reset your transmit frequency to the new frequency.
If you forget and see that you are transmitting at the old frequency, press PB2 (or encoder switch) and the new receive frequency will come back, then press PB2 (or encoder switch) and hit the key to set the correct transmit frequency.
PB3
Cursor to Right
Momentary depression moves cursor to the right one decade position. The cursor will wrap from the 1 Hz decade to the highest decade. Holding down for one second will start automatic movement of cursor to right every 1/8 second.
Band Change
Depressing PB3 and moving encoder before one second will enter band change mode. Moving the encoder will cycle through all the bands configured and releasing PB3 will select last band displayed.
Key Connection
The "KEY" notation on the board is where a key, either hand key or an iambic keyer, is connected to send CW. This "KEY" connection is grounded to activate the transmit function, activate the T/R switch, and send the signal to the transmitter. A diode, the anode connected to the output of the PIC to PB1 is used to isolate it from the keying line. Also, a diode (anode side) is connected to the PNP switch of the T/R switch. Then both cathodes are connected together for the connection to the keyer, which grounds the two cathode diode connections when keyed. There are two KEY connectins, one on the DDS VFO at PB1, and a second one at the T/R switch labeled "DDS VFO Key" at the edge of the board. This second connection is the easiest to connect the line to the keyer.
Tuning Range of the DDS VFO
The bands are chosen with the DDS VFO by pushing Button 3 and turning the DDS VFO knob within one second. The DDS VFO will scroll through the bands until it reaches the one you want and quit turning the knob.
The bands on the DDS VFO are 160/80/60/40/30/20/17/15/10. The next band is 200kHz, which does not have the offset programmed and is a signal generator that outputs the exact frequency it is showing. It is used to determine the center frequency of the crystal filters so it can be programmed into the offset frequency if the crystal filter frequency is changed.
To use this function, tune the 200kHz band near the frequency of the Crystal Filter frequency and peak the output at the S-Meter. Use the 100 Hz or 10 Hz tuning digit to find the peak. The peak frequency is then the offset frequency put into the programming for the bands.
The next band shows 0 and is a general coverage band that has the offset programmed (plus 3.546 MHz) and can be used to go to any frequency between the limits of the Bandpass Filters, below 60 to 10 Meters.
The Band numbers showing on the display go from 1 to 9, 3.500 to 24.890 (80 to 12 Meters). On 10 Meters it shows :, on General Coverage band 0, it shows ;, and on 200 kHz, it shows >. I guess the original programming didn't go above a one digit number. This will probably be fixed in a future release, but it doesn't effect operation.
Bandpass Filter Tune Potentiometer
 Ham Radio Bandpass Tune - Width 1.6" by 1.4" 40/30 Bandpass coils 35 turns
The image above is a .gif file that can be right clicked and downloaded. Open it in a picture program, resize, print and trim to help find the bands.
Some of the bands will have two peaks, one at the indicated marks and one slightly off to one side. Either works fine.
BFO Adjustments
BFO -Width 1.25" by 0.9"
Put the BFO cap in the middle of its range and then adjust the BFO coil for Zero Beat.
Audio Control
Width 1-3/4" (1.75) by 1-11/16" (1.7)
This potentiometer can be either 5K or 10K. As the pot is turned clockwise, volume should increase. If it decreases, switch the leads to the outer ends of the soldering tabs.
A plastic/insulated knob should be used, as hum and commercial stations could be picked up through your hand into the pot to the audio amplifier.
If the pot has a metal case, a ground wire soldered to the case of the pot will reduce pickup problems. Ground connections were placed in the area for this reason.
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