----- Original Message -----
Subject: [softrock40] Anomalous R 32 and R 33 voltage versus frequency values
> Hello group. After assembling my ensemble 2 receiver, I tested the voltages on resistors R32 and R33 versus frequency. The R32
> voltage values changed considerably, while the voltage vs frequency for R33 remained very close to the nominal 2.50 volts. The V
> vs Freq remained within 0.3 V for R32 & R33 up until filter bands 2&3, when they began to diverge. There was a big broad dip
> between 8 MHz & 16 MHz bottoming at about 1.83 V @ 13.2 MHz for R32. R33 @ this freq was 2.42 V on a Fluke 289 VOM.
> At 16Hz, R32 = 1.86 V, dropping from 2.18 V as the Freq passed into filter band 3.
In fact this is not unusual. It is said to be due to a slight imbalance of stray capacitance in the mixer.
> All other voltages are normal. The receiver works very well on the lower bands, but degrades with respect image suppression on 20
> meters and above.
> I reflowed T3's solder points to no avail. All pin/pad voltages are nominal. Soldier joints look good. Clock performance okay on
> my Tek 454 scope.
Uncorrected image rejection may reduce at higher frequencies due to them being more affected by stray capacitance and tolerances.
73 Alan G4ZFQ