N3ZI DDS 2


Display showing 1Hz resolution
(8 on the left is memory number)

Closed for the holidays, Reopening Jan 15, 2015
Paypal orders will be accepted, but not shipped until Late Jan 2015


My first DDS has been very popular, but there have been a few requests for improved performance. The chip I chose for that design was the lowest cost chip available for the HF frequency range. The initial request for expansion was the frequency range, the first version was limited to 20MHz output, but I was able to overclock that inexpensive get to get 30MHz out.

So I have redesigned my DDS, now called DDS2, using a different DDS chip, AD9834.  This has many improvements and is only slightly more expensive.
Download Manual
Includes improved firmware with quick tuning step change
Manual w/ Schematic

Click here for some photos of various LCD configurations


Basic Kit

Deluxe Kit
(DDS SMT Chip Soldered to PCB)
Photo here (7 Segment LCD)
Photo Here (Backlit LCDs)

Price

$45.00
PAYPAL
LCD
Your Callsign

Lead Time
(Business days)

3-5 Days

5-10 Days

Shipping
(PayPal)

$3.99 (US)

$4.99 (US)

Sales Tax

None, except Nevada

None, except Nevada

LCD Included

None

Choice of 7 Segment or
Alphanumeric w/ Backlight

DDS Chip

Not included

Included and Soldered to PCB

Number of Surface mount parts to solder

1

none

Programmed micro with universal LCD driver F/W

Included

Included

Top Quality US made PCB with plated through holes and silkscreen.

Included

Included

Encoder

Mechanical

Mechanical w/ Push Switch

80MHz Master Oscillator

Included

Included

Rig Control

RS232

RS232

Step Size

1Hz

1Hz

Tuning Speed

Fast and Smooth like analog VFO

Fast and Smooth like analog VFO

Freq Range

0.1 to 32MHz

0.1 to 32MHz

Features

RIT, FSK, PSK, VFO A/B, 10 Memories

RIT, FSK, PSK, VFO A/B, 10 Memories

IF Offset, One per memory band, VFO+IF, VFO-IF, or IF-VFO

Included

Included

User Settable EEPROM Parameters

Yes

Yes

Use Orange buttons above to order through paypal

Hardware now for sale

Info on Buffer Amp
Used Metal Optical Encoder Info (sold out)
New Plastic Optical Encoder Info (Sold out)


Significant Improvements:

1) 1Hz step size.  This was the most requested  improvement, and this chip has it.  Furthermore the LCD will display the frequency with 1 Hz resolution.  I'm going to set the step size to something higher than that, but those of you who demand precision will be able to change the default step size.  The LCD display will show 9 digits of frequency (a sign, 2 megahertz digits, 3  kilohertz digits, and 3 Hz digits.  

2) No (or very little) overclocking.  All these kits will be shipped with 80MHz clock modules.   This along with an improved output filter will allow operation up to 34MHz.

3) Fast RIT and FSK.  This chip has two frequency registers, and there is a direct connection to select between the two.  Switching is instantaneous and phase continuous, you can use it with CW QSK and even FSK (RTTY) is you want.  The push switch on the rotary encoder allows you to set the RIT offset, tuning speed, and calibration.

4) Vastly improved Encoder tuning.  The dial now operates much like an analog VFO dial.  I have an acceleration algorithm that works very nicely, so the push switch for speedup is no longer required.  New debounce and other changes make the action smooth like an optical encoder using an inexpensive mechanical encoder.  There is no lag for the LCD, and no queuing, no glitches,  and catch-up.

5) Phase continuos frequency changes.  The old chip had to be turned off then back on for a frequency change.  So there was a brief but noticeable glitch.  The new chip has phase continuous frequency changes meaning than the instant a new frequency is selected, the output waveform continues smoothly by sloping and the proper rate for the new frequency


Features and Specifications:

Feature

DDS
(sold out)

DDS2

Maximum Output Frequency

20 or 30 MHz

34MHz

Step Size

10Hz

1Hz

LCD Display Resolution

100Hz

1Hz

Tuning Speed

500ms per step

Instantaneous

RIT

None

+/- 1Hz to +/- 10MHz

QSK support

No

Yes

LCD update lag

500ms

not perceivable.

Cost

$50 to $70

 $45 to $85

Tuning

Discontinuous (glitch)

Phase continuous (no glitch)

Number of Surface mount parts

1 16Pin TSSOP

1 20Pin TSSOP

Memories

10

10

A/B VFO

Yes

Yes

FSK and PSK support

None

Yes

LCD Included

Yes

Yes

Works with 3rd party LCDs

Yes

Yes

Encoder Included

Yes

Yes

Chip Used

AD5932

AD9834