2N2/40+, A 40 Meter CW Transceiver

Transcription

1 N/0+, A 0 Meter CW Transceiver B T TP-0TS/T7- C Rx Input Filter pf C 00pF TC -70pF TC -70pF C 00pF T C7 0TP-TS/T7-0.0uF L 00uH R 8 T ::T/FT7- T Q. RF Amp +db T T. FB Mix.9 C 0.uF R.K D8 v C 0.0uF C 0.uF T 0T Trifilar/FT7-.9 R 7 DB Mixer D N8 D N8 D N8 D N8 T 0T Trifilar/FT7- C.9 D N7A 0.7 D N00 C R 0 A POT 0K-0T C B R0 K Varactor Tuned, Buffered VFO C C 0.0uF R 7K TC -0pF C7 0pF D7 MVAM09 D C8 0pF L T/T0-7 C 0pF C9 7pF TC 8-0pF R.K R 0K. Q. C0.7 R 0.00uF 0K C 0.00uF.9 R K R7 K.9 Q. R8 TP-8TS/FT7- T 0K VFO C 0pF...9 Q R9 90 Note: TC is optional C0 & C are % polyester C8 is polystyrene; C is NPO C7 & C9 are NPO Note: Select C from 70-90pF for max outpu N0+AA.SCH; 0000

2 N/0+, A 0 Meter CW Transceiver C L 00uH C D N8 R Mixer Amp +9dB R.7K 0.7 Q. L 00uH C9 R8 70 R9 00K Y.9MHz C 80pF Variable Xtal Filter 0-70 Hz R9.8K C Y.9MHz D9 MV POT 0K R0 00K Y.9MHz D0 MV.0 D v.0 D v C 80pF T7 TP-TS/FT7- C8 R.7K C8 R 7 IF Amp +0dB R 7K. 0.. Q C 80pF R K.8 C R 80 R T8 0T Bifilar/FT7- C 0.0uF.9 T9 0T Trifilar/FT7- Q7 R7 7 Product Detector D7 N8 D N8 D N8 D N8 R K C8 0.uF C7 C C7 0.uF.7 Audio Pre-Amp +0dBv R K R 0K C 0.0uF. R K. 0. C0 Q R 00 R8 90 R7 0 C.7uF Rx Local Oscillator Y.9MHz L 9uH R 0 R8 0K TC -70pF R7. K. C0.7 00pF C 80pF R 0 Q8 R 70 C7 L uh C9 7pF D9 NA D0 NA R 0K Rx D8 N8 C Rx Mute R0 M D G S Q J7 C 0.uF R M POT 0K.9 C.9 R7 9K C.7uF C9 70uF Q9. 70 Q0 9K R9 C0 70uF.9 R.9 R8 70 R0 70 R.7K Audio Amplifier. Q R.7K C. Q.9 C 0.08uF C 70uF T0 00CT - 8 LS SPEAKER Note: Select R0 for desired audio level N0+BA.SCH; 0000

3 N/0+, A 0 Meter CW Transceiver Y.9MHz Local Oscillator R0 0K L7 9uH R 0 C R9 K 0.0uF C8 00pF C9 80pF Q R K VFO C0 7pF SB Mixer C 0.00uF T 0T Trifilar/FT7- D N8 D N8 D N8 D N8 T TP-TS/T7- TC7-70pF 90pF C C 70pF Cascode RF Amp C 0.0uF R 0K R.K R0K R7 00 R 0K C7 0.0uF Q7 Q C 0pF T TP-TS/T7- POT 00 TC8-70pF TC -70pF R8.8K C8 0.0uF R9.K R0 0 C9 RF Driver C0 0.0uF T 0TP-TS/FT7- C Q8 NA D N8 R 8 L8 7T/FT7- C R 00 A C D N7A R. L9 7T/T7- C7 0 SM Q9 NA Output LP Filter C C8 80 SM R. L07T/T7- Q0 NA C9 0 SM C R. Antenna Q NA C Note: NA is a TO8, metal case device RF Final Amplifier(s) N0+CA.SCH; 0000

4 N/0+, A 0 Meter CW Transceiver Rx/ Driver (J7 Rx Mute) Rx T/R Switch Rx R9.7K R8 7K R.7K Q Q R7.7K C7 0uF A TC9-70pF D7 N8 L uh D8 N8 B POT K Key Line C70 0.0uF Note: This capacitor mounts at connector for keyline TC9 can be 7pF, L 0uH, for fixed tuned input Adjustable Span RIT POT "A" +.8 vdc Gnd F A Input Power S SPST D9 N7A Note: S part of POT C7 0.00uF R70 0K R7 K R7 K Q N7000 R7.K R7 K R7 7K C7 0.0uF R7.K POT "C" L "D" TC0-0pF D0 MV09 Note: TC0 can be fixed 7pF for fixed RIT span N0+DA.SCH; 0000

5 N/0+ Receiver Alignment Overview: This procedure is used to do the alignment of your N/0+ when you have the receive portion of the rig completed. Correct alignment is necessary to obtain the best performance from the receiver, and done incorrectly, may render the receiver incapable of hearing any signals except for the very strongest. The basic process is to adjust the receive local oscillator so that it is about 700 Hz below the center of the filter pass band, when the filter is adjusted to its narrowest bandwidth, at around 0 Hz. A diagram is provided for reference. It shows the extremes of the filter; when it is adjusted as wide as it will go, and at the narrowest bandwidth. These extremes are at 70 and 0 Hz pass band bandwidths. Referring to this diagram, please note these important features. The center of the narrow pass band is at about.90 MHz. That point is shown in this diagram as point A. This is typical of the filters using crystals with a marked frequency of.9 MHz. The center of the pass band of the filter is above the crystal s marked frequency by a few hundred Hz. The design of the N/0+ uses this filter as an upper sideband filter. That means the received signal will be somewhere in the pass band of the filter, above the frequency of the local oscillator driving the product detector. The product detector is the stage used to convert the received RF signal into an audio signal. The reason that an upper sideband configuration was chosen was to minimize receiver retuning when the pass

6 band of the filter is narrowed. As shown in the figure, when the filter is narrowed, the upper slope is the one that changes frequency. The lower slope changes its attenuation characteristics, but not where it is located in frequency. For the receiver to be properly aligned to hear CW at 700 Hz, the receive local oscillator must be below the center of the narrow filter pass band by the same amount as the note we desire to hear when receiving. If 700 Hz is the desired note, then the receive local oscillator needs to be lower in frequency than point A. The 700 Hz offset is shown on the diagram as point B. With these facts in mind, let s proceed to doing the alignment. ) Set the filter pass band to its widest setting. Set trimmer capacitor TC to its maximum capacity position by either listening to the receiver local oscillator on another receiver tuned to approximately.9 MHz, or by measuring the output frequency of the local oscillator. This measurement can be made by attaching a counter probe to the ungrounded end of L and adjusting TC for the lowest frequency obtainable. ) Tune the receiver to a signal, or if possible, generate a signal about mid-band, around 7.00 MHz. Tune across this signal by rotating the tuning potentiometer POT. Notice that as the tuning potentiometer is rotated clockwise, the audio pitch of the received signal goes lower. ) Listen for a peak in the audio response as the signal is tuned. We want this peak to occur at about 700 Hz. With TC set for maximum capacity, the peak is probably upwards of 00 Hz. Slowly rotate TC to a lower capacity setting. Go a little at a time, and return the receiver, listening for the audio peak. You will hear it progressively moving to a lower pitch. As the pitch comes down, you can start narrowing the filter pass band too, to begin homing in on the very best setting. ) Repeat the adjustment of TC and retuning the receiver until the pitch is where you like to listen to CW, the filter is as narrow as it will go, and the audio is the loudest you can make it. That s it..the receiver is aligned.