First, set the BFO frequency, peak the 455 KHz IF Strip, and adjust the BFO Amplifier.Set the BFO Frequency____Connect a 40 or 20 meter antenna to the receiver.  Note: If you do not get a rushing noise out of the receiver, the first place to check is the BFO. It is very easy to accidentally ground the BFO tuning capacitor. Click here for diagnostic information. TroubleshootingPeak the 455 kHz IF strip____Adjust the "Filter Tune" pot on Board 1, until you hear a noise peak. Both 40 and 20 meters have very good peaks.____Readjust the BFO 455 KHz IF can where you hear the band noise and set to zero beat with the BFO cap half meshed. ____Go back and forth between the two adjustments, if need be, to get it right. ____Adjust the BFO tuning cap for one of the sidebands, at a higher tone than zero beat. ____Peak the first two 455 KHz IF cans on the 455 KHz IF Strip for best reception/noise. The white core will be 3/4 turn down from the top (first IF can). The yellow core will be two turns down from the top (second IF can) (approximately). The peak is not real sharp, but is easy to define. ____Run the core all the way up on the third 455 KHz can next to the AGC detector. There is tons of gain here. You can adjust it for a peak when listening to a strong signal for maximum AGC action.TroubleshootingAdjust the BFO Amplifier____Adjust the "Gain Adjust" trim pot at the BFO until the LED just begins to light. It should be at full brightness when the receiver is first fired up. The best setting for minimum noise is where it just begins to turn on. This is not critical at all and can be set where you get the best audio.____Run the core all the way up on the 455 KHz IF can at the BFO Amplifier, next to the Product Detector. There is tons of gain here. It is not necessary, but you can use an oscilloscope to peak this can, connecting to the output side of the 47pf capacitor below the can. TroubleshootingAudio Pre-Amplifier/Audio AmplifierUse a 4" or 6" 8 watt, 4 ohm speaker (or larger) for best results. TroubleshootingThird, Adjust the S-MeterDouble check that you have installed the proper MTR1 and MTR2 resistor values for the S-Meter you are using. 50uA Meter Multimeter - Values shown on the Board. The adjustment for the Zero Adjust pot will be near 3/4 of the way counter-clockwise. Dimming the IF LEDs will shut off the IF strip! ____Disconnect the Antenna from the receiver.____Have a clip lead connected to one of the Bold AGC boxes, the other end will be grounded to adjust the S-Meter. ____Adjust both the Zero Adjust and the Sensitivity trim pots all the way counter clockwise. The S-Meter should be reading almost full scale. ____Move the Zero Adjust trim pot counter clockwise until a zero reading is obtained. NOTE! You may not get the S-meter all the way to zero until the Sensitivity pot is adjusted. ____Ground the AGC line with the clip lead, the S-Meter should be off scale to the right. ____Move the Sensitivity pot till full scale reading is obtained. ____Remove the clip lead from Ground. The S-Meter should be off scale to the left. ____Move the Zero Adjust pot counter clockwise until a zero reading is obtained. ____Ground the AGC line with the clip lead, the S-Meter should show full scale reading. Your S-Meter Zero and Sensitivity adjustments should be close to what is shown in the picture below. |
____If more sensitivity is desired, turn the Sensitivity pot counter-clockwise until the desired sensitivity is obtained. Having a signal tuned in will make this adjustment easier. At the more sensitive positions, the S-Meter will read past full scale when the AGC is grounded. Readjust the Zero pot so that it reads zero at no signal.Troubleshooting |
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