Page 1: ...adjusted except the audio gain control Front panel mounting of the controls permits a compact physical layout to be obtained wr FEATURES Simple to construct Uses inexpensive parts Has sideband reversing control Usable as emergency portable or home transmitter CONTENTS SSB Jr pages 1 9 Designer s Corner Notes on the design of the SSB Jr rig page 10 Sweeping the Spectrum page 11 Technical Informatio...
Page 2: ...mmer in parallel 1215 mmf 0 001 mf mica 5 with 50 380 mmf trimmer in parallel RFC R Rº Rs Radio frequency choke 0 5 millihenry 1 megohm potentiometer 10 000 ohm watt 750 ohm watt C 607 5 mmf S00 mmf mica X10 with 9 180 mmf trimmer in Parallel R Rs 430 ohm 3 1 watt 5 100 ohm potentiometer Cu n C 0 005 mf mica or ceramic R 1600 ohm A watt 5 C C 350 mmf 600 volt mica X10 250 mmf in parallel with 100 ...
Page 3: ...ed for a special transformer or the need for two non standard precision resistors Stable modulator balance is achieved by the balance buffer resistors R16 and R17 in conjunction with the ger manium diodes The audio characteristic of the SSB Jr is designed to emphasize the intelligence bearing frequencies from 300 to 3000 cycles per second This feature is obtained jointly by the action of C1 and th...
Page 4: ...ource of power supplying 300 volts and 60 mils or more may be used It is not necessary to use electronic bias either and a standard battery sup plying 10 5 volts may be used for bias 4 The power supply used with the SSB Jr rig pic tured is shown in Fig 7 and the circuit diagram given in Fig 6 A 5V4 G rectifier tube feeds a single section filter to supply 300 volts and a 6H6 tube acts as a bias rec...
Page 5: ... 2 SPACERS Ti STANCOR e No3c Sill L ____ _ T I i xi r 1 I I2AU7 t i i r 1 1 i 1 2 L___ J n 4 ii 1 XTAL FRONT SOCKET LI BELOW R5 USE SHAFT LOCK r II J I i 12AT7 i C2 a b c d CABLE OUTLET c 5 X 7 X 2 CHASSIS i AG7 KEEE L2 L3 L4 ABOVE BELOW ABOVE L5 BELOW Fig 5 Chassis layout for the 55B Jr top view 411 5 ...
Page 6: ...n an accurate bridge The adjustment of the phase shift network now consists only of setting the four capacitors C7 through C10 to their proper values Several methods can be used The most accurate will be described An audio oscillator capable of operation from 225 to 2750 cycles per second with good waveform is required plus an oscilloscope The oscillator should be carefully calibrated by the metho...
Page 7: ...As a double check if the deflection plates in the oscillo scope are skewed for instance connect lead 2 to terminal A If the circle changes to a slanting ellipse readjust C7 to produce an ellipse half way between the ellipse obtained by switching lead 2 and a circle Changing lead 2 from A to A and back again should give equal and opposite skew to the display when C7 is set correctly Failure to get ...
Page 8: ...in a crystal 3850 to 4000 KC or supply a signal to the crystal socket from a VFO at not less than a 10 volt RMS level set L1 and L2 for minimum inductance slug out counterclockwise and apply power The current drain should be about 35 to 40 MA at 300 volts under this condition with the oscillator operating If the current drain is over 45 MA turn off the B power adjust LI reapply power etc until the...
Page 9: ...g L2 will be degraded sideband suppression It is quite important therefore to adjust L2 very carefully It may be noticed that when large audio signals are applied the envelope develops some ripple There are two possible causes for this action The first is carrier unbalance carrier shift and the other is harmonic distortion in the audio circuits It is assumed that a pure sine wave of 1225 CPS is us...
Page 10: ... simplification which deserves comment is the balanced modulator used in SSB Jr Let s take a few moments to consider what takes place in the cir cuit Fig 13 shows just one modulator consisting of two germanium diodes G1 and G2 with associated cir cuits First suppose a high frequency signal of a few volts is applied at point R On the positive crest of signal current passes through G2 into the cente...
Page 11: ...k this new language into an inverted speech system what comes out is understandable English As an example metz pee wee means nuts to you and eee wye says oh yeah But you can go even further as Don and I did We decided that it would be nice to be able to recite the poem Mary Had A F Little Lamb in inverted speech and after an hour of intense concentration we succeeded in the decoding job We thought...
Page 12: ... 7 µµf DESIGNER S CORNER Cont band 3850 to 4000 KC There is no reason however to think that equally successful performance would not be obtained on 20 or 10 or even on what is left of 160 It s simply a matter of coil design The unit pictured in this issue of Ham News was the second one ever built Ten minutes after the last solder joint had cooled down the rig was perfectly adjusted and was deliver...
