Frequently Asked Questions

1. In what rigs has the N4YG DDS system been installed?

The N4YG DDS system has been installed in the Heathkit HW-101, SB-101, SB-102 and SB-104 Ten Tec Corsair I, Corsair II, Argosy and OMNI D, Drake TR7, RV7 and TR-4. It has been used to construct a standalone VFO.

2. What do I need to purchase and what else will I need in order to install the N4YG DDS system in my particular rig?

Complete kits are available for purchase on this site for Ten Tec rigs with PTOs and the Drake TR7/RV7. For Heathkit transceivers, kits are available which include all of what is required, but some construction is required. You may download the installation instructions from the download page. This will show you what is required to complete the installation.

3. Is there a kit which requires minimal effort to install?

Yes. For those not particularly proficient in soldering, a kit which includes the completed DDS board which has been tested and is fully functional. The board is fully connectorized, meaning that no interconnecting wires are soldered to the board. All that is required is to connect a few wires to points within your rig and plug the connectors into the board.

4. I have noticed some differences between information provided on the N4YG DDS system in "QST In depth" and some of the material on this web site. Which is correct?

There are several errors in the material on the ARRL web site. Always download the latest instructions and reference material from this site.

5. What is the power source for the N4YG DDS system?

Since the board was originally designed for the HW-101, it was designed to receive power from a 12.6 (approximately) VAC source. Since only the older rigs have such a source, a retrofit modification (for no additional charge) is available which allows the system to be powered from DC voltage, 8 to 13 VDC.

6. Can I purchase the PC board and parts and assemble the board myself and save some money?

You sure can. If you are comfortable with a soldering iron, you should be able to assemble the board and save some money.

7. I am good with a soldering iron, but I have never soldered a surface-mounted TSSOP chip like the AD9835. Should I attempt to mount it on the circuit board?

If there is any concern, attaching the AD9835 to the circuit board should not be attempted. The TSSOP chip is tiny, only 0.2 inches by 0.2 inches. The tiny leads are spaced 0.0256 inches apart. You may purchase the board with the AD9835 already attached for an additional $10.

8. I am ready to assemble a circuit board and I am having trouble seeing the small details. Any suggestions?

Yes, I highly recommend that you purchase item number 38896 from Harbor Freight. It is a Magnifier Head Strap with lights and the cost is only $6. One of the most useful tools I have ever purchased.

9. I have heard that DDS systems have numerous spurs in the output. Does the N4YG DDS system have spurs?

All DDS systems have spurious outputs. The spurs are very narrow band and move around in frequency as the DDS is tuned. In the N4YG DDS system, all spurs are at least 60 dB down from the desired output.

10. Will I be getting reports of spurs in my transmitted signal?

Absolutely not. Most commercially available amateur transmitters have spurious output specification in the -50 dB range. With the DDS having a spurious output of less than -60 dB, DDS spurs will never be heard in your transmitted signal.

11. Will I hear spurs in my receiver?

Yes, you very likely will hear some low-level spurs. These will be like low-level birdies, but they have a much more narrow-band character. Depending on the rig and the receiver architecture, the spurs may be barely detectable, while in others they may be noticeable, particularly with quiet band conditions or with no antenna connected. In many transceivers, the VFO is input to a mixer, the output of which goes into an IF amplifier. If the VFO frequency is near the IF frequency, that can be problematic. The HW-101 is an example of this situation. In this case any spurs that occur at or near the IF frequency tend to go directly through the mixer and into the IF amplifier. Luckily a trap tuned to the IF frequency will remove the offending spurs. This is done with the HW-101. The IF frequency of the Drake TR-7 is far removed from the VFO frequency and offending spurs tend to be smaller and not a problem. Overall spurs do not tend to be a problem for most receivers.

12. I have installed the N4YG DDS board in my rig according to instructions but I hear noise when I rotate the tuning control. What can I do to eliminate this?

In some rigs, this may be caused by a ground loop. This has occurred in the Ten Tec Corsair II in particular. You can probably eliminate it by disconnecting the ground wire which come from pin 2 of J6 on the DDS board to the chassis ground of the rig. The board will still be grounded to the rig chassis through the standoff mounting through the regulator, U5.

13. Are the SMART Keyers still available? SMART Filter?

MSC not longer exists. N4YG is not in the business in the same way. Some of the key parts associated with the SMART Keyer series and SMART Filter are obsolete and either not available at all or the price has increased to the extent that it is no longer practical to produce them.

14. I have lost my manual for my SMART Keyer or SMART Filter. Do you have a replacement?

Check out Old Stuff on the downloads page.

15. My SMART Keyboard (or Key-n-Log) was working fine and all of a sudden it does not work right. Is it broken?

No, probably not. You are most likely getting RF into the USB cable. You need a shielded cable. If you ordered a parts kit from us, you most likely got shielded cable. Our shielded cables are white. You can check to see if the problem is RF by simply turning the drive to your transmitter down very low. If everything is fine, you have an RF problem. If you advance the drive you will reach a point where bad things begin to happen.

16. I have constructed the SMART Keyboard Interface Unit. I have it connected to my computer and have paddles plugged into the "PADDLES" jack, but when I close the paddles I hear nothing from the sidetone. What is wrong?

The volume is probably set to zero. Run the GUI. You should get the message, "Firmware Version 0.2.0", in the Alert Area. If you do not get that, the host computer is not finding the Interface Unit. The problem is either with the Interface Unit or the computer operating system. Remember, the operating system must be Windows 98 Second Edition(SE) or more recent. If you do get the message above, increase the volume to about 20 and type something in the Keyboard window. You should hear CW.

17. How do I connect the SMART Keyboard Interface to my rig and paddles?