March 2008 QST Feedback
The photo caption of President Joel Harrison, W5ZN, with Senator Mark Pryor [January 2008, p 13] identified the senator as a Republican. He is in fact a Democrat.
In “2007 ARRL International DX Phone Contest Results [Oct 2007, pp 95-100], KA5PVB was incorrectly listed in the Single Operator, Low Power category. He should have been listed in the Single Operator QRP category. This change puts him in fourth place overall in his correct category. The ARRL regrets the error.
In “Building the Tinker Box” [Jan 2008, pp 35-38], the schematic in Figure 1 is authentic based on the original; however, it introduces a safety risk not acceptable in peacetime. There is no bleeder resistor in the power supply to discharge the filter capacitor after turning the set off. We suggest that those building copies insert a bleeder of around 40 kW at 10 W in parallel with C11. As with any safety device, always assume it has failed and ground the positive side of C11 with a shorting stick to be sure.
In “Product Review—ICOM IC-R9500 Communications Receiver” [Jan 2008, pp 69-73], Table 1 on p 71 has two errors. The correct value of the measured IMD DR for 14 MHz at 5 and 2 kHz spacings is 92 and 81 dB, respectively.
In “Feedback” [Feb 2008, p 44], pins 4 and 5 of the opto-isolator are reversed.
In “Hints & Kinks” [Feb 2008, pp 80-81], the item “Two Speed Soldering Iron” actually reduces power by 50%, not 75% while the diode is inserted in the circuit. This is a result of the duty cycle being reduced by 50%.
In “Old Radio” [Feb 2008, pp 96-97], the modified electronic keyer schematic did not show the pin connections for the change to the 6C4 triode. The pins are as follows: filament, 3 and 4 (not center tapped); grid, 6; plate, 5 (or 10) and cathode, pin 7.
Page last modified: 01:20 PM, 04 Feb 2008 ET
Page author: qst@arrl.org
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