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July 2006 QST Feedback

The two Maine hams who worked on the Field Day tower base [Up Front in QST, Jun 2006, p 20] are Ben Benedetti, N1HPU, and Ken Orne, K1BEA.

In May 2006 "Hints & Kinks" [pp 62-63], the references in the equation and the examples to "pF per inch" should be "pF per foot."

In June 2006 Product Review, p 71, first full paragraph, the reference to a previous QST article by Ed Wetherhold should have been to the two-part article "Clean Up Your Signals with Band-Pass Filters," May and June 1998.

In "An Effective 160 Meter Receiving Loop" [Jun 2006, Figure 8, p 38], R4 should be between R3 and D5, not as shown following D5. Also, T1 is specified as center tapped. The center tap should be shown and indicated as "not connected."

In June 2006 "Technical Correspondence" [Figure 2, p 73], the spacing shown should be H Plane Spacing, as in Figure 1, not E Plane Spacing as indicated.

In June 2006 "The Doctor is IN" [footnote 1, p 55], Roy Lewallen's call sign is actually W7EL.

The name of former GE chairman Jack Welch was misspelled on page 104 of the June 2006 issue. -- tnx Bob Johnson, W4MKO

In "In Loving Memory: Father Moran, 9N1MM" [Jun 2006, p 49], Gus Browning's call sign was W4BPD. -- tnx Art Pahr, K9XJ

Update: Author Gary Richardson, AA7VM, reports that there have been some problems with excessive clock noise in generators built from his article, "A Low DDS Function Generator" [Nov 2005, pp 40-42]. He notes that he has been unable to entirely eliminate the noise from the outputs, but it can be reduced quite a bit by tacking a 0.1 µF capacitor across pins 4 and 8 of U2. For best results, keep the leads as short as possible. If in your circuit C4 and C9 are electrolytic capacitors, it may also be helpful to replace them with tantalum capacitors.

The output must be taken from pins 1 or 7 of the op-amp and AGND. There should not be a connection between AGND and DGND at the connector.

The best way to observe this noise is to set the frequency to zero. He reports seeing about 15 mV_pp spikes at the 10 MHz clock frequency. After making these changes, noise has been reduced to about 2 mV_pp.