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Winter QRPp 2N2/40 Article Corrections - V1.5
Page 17 - Capacitors C67 and C68 are missing from the drawing. C67 is a 4.7uF electrolytic which goes between the pad containing the connections to R59, R60, and C66 and ground. C68 is a 0.01uF ceramic connected between the key jack, J2 keyline and ground, to bypass r.f.
Page 19 - Capacitor C7 is missing from the drawing. This capacitor (0.2uF) connects between the pad with VCC4/VCC5 and ground. The rig will probably work fine without it, but it should be included.
23 - The connection from transformer T1, pin 4 is missing. Pin 4
should connect to the pad at the junction of capacitors C1 and
C2. Without this connection, no input signal will get into the
receiver. In addition, transformers T1
Page 25 - There is a missing pad and parts between the emiter of Q6 and the output, pin 4, of T7. The required emitter resistor is 47 ohms, (R66) and this resistor is in parallel with a 0.2uF capacitor (C18). These parts are also not shown on the schematic, as the schematic is an out-of-date version, but has been updated on the K8IQY web site. ( http://www.qsl.net/k8iqy ) The parts list has also been updated to show R66, instead of the duplicate R65 designations in the article version. An alternative to adding R66 is to substitute a 1N4148/1N914 diode for resistor R20, (3.3K) and change resistor R21 (47K) to a 6.5K value. This will provide the correct bias to Q6.
Page 31 - Transistor Q12 is not drawn in the correct orientation, nor are the "c" and "e" labels correct. It should be in the same orientation as Q13, with the base lead going to the original pad, e.g. to the right as shown in the illustration. The collector is soldered to the pad currently labelled as the "e" designation, and the emitter is soldered to the pad currently labelled as the "c" designation. The amplifier will not work with the transistor installed as illustrated. The electrolytic capacitor connecting to the pad containing R37, R38 and the emitter of Q12 is not C38, but C40. Capacitor C38 is already shown connected between the pad containing the center terminal of the volume control, and the pad connected to the base of transistor Q11.
35 - Transformers T12 and T13 are wound on T37-2 toroids, not FT37-2
cores as shown in the detail insets. In addition, there is a pad
and a part missing. Another pad is needed to which resistor R44
is connected. The other end of
37 - Transistor Q17 is a 2N2222A, TO-18 device, not a plastic version
as illustrated. The transistor should also use a heatsink.
Install Q17 in the same orientation as Q18-Q20 e.g. emitter to the
left, base down, and collector right. Update the "NOTES:" section
to include Q17 along with Q18-Q20. The Q19 emitter capacitor,
labelled as C61, is acually C62. The Q20 emitter capacitor,
labelled as C62, is actually C64. The capacitor labelled C56
There is a general problem with many of the transformer illustrations in the article in that either the primary or secondary designators are reversed. For example, the T1 illustration on page 23 shows the windings drawn correctly, i.e. the winding direction on the secondary continues from the direction of the primary, but the secondary numbering is reversed. The "start" of the winding is labelled "4", but should be "3", and the finish of the winding is labelled "3", and it should be "4". If you look at the illustration for T2 on the same page, the primary is labelled correctly, and the secondary winding direction is correct if the secondary numbered labels are reversed.
If anyone finds anything else, please e-mail it to k8iqy"at"k8iqy"dot"com. Your help is greatly appreciated. Sorry for any inconvience these errors may have caused.