HP 8340B Manual page 182

5-14. UNLEVELED RF OUTPUT ADJUSTMENTS (Cont'd)
Remove jumpers A28W1 and A28W2 if they are installed on the A28 assembly. These jumpers
must be removed to set the V/GHz circuit to 0.5V/GHz.
6. If the A26 assembly has been replaced, preset the following pots to the position stated (see Figure
5-41):
Set the following fully clockwise:
A26R88 (MO)
Center the following:
A26R7 (BAL)
A26R49 (X3)
0.5 V/GHZ ADJUSTMENT
7. On the OUT, press [CW][1][0] [MHz].Adjust A28R67 (V/GHz) for a DVM indication of 5 mV + 0.5
mV.
SYTM TRACKING AND UNLEVELED SRO BIAS ADJUSTMENTS
8. On the OUT, press the following key sequence:
[STARTFREQ] [6]
[STOPFREQ] [1] [3]
[POWER LEVEL] [0] [dBm]
(SWEEPTIME] [2] [0] [0] [msec]
[XTAL]
[SAVE][1]
9. Connect the oscilloscope and detector as shown in Figure 5-40. Set the oscilloscope to A vs B
mode, horizontal sensitivity (CHAN B) to 1 V/Div dc, and vertical sensitivity (CHAN A) to 0.05 V/Div
dc. Adjust the horizontal and vertical position controls to view the entire swept RF output
response on the oscilloscope. Readjust the vertical sensitivity if necessary so that the trace
covers the maximum number of divisions possible.
Band 2 Adjustments
10. Adjust A28R82 (GAIN) to peak the power across the entire band (readjust the scope's vertical
position and/or sensitivity if necessary).
In the following adjustments, turning the X2A/B, X3A/B, or X4A/B con-
trols clockwise when in the appropriate band will increase the SRD bias
and be closer to the squegging region'. If squegging occurs, turn the
above controls counter-clockwise until the RF output power is reduced
0.5 dB below the squegging region.
1. The squegging region is an area where undesired oscillations of the YIG sphere or Step Recovery Diode (both internal to the SYTM) are
produced. Symptoms of squegging are power reversal (actual RF output power decreases as selected RF output power is increased), power
holes in the RE output, and spurious responses on the RE output.
5-76 Adjustments
A26R43 (HET)
A26R51 (X4)
[9] [GHz]
[.]
[5] [GHz]
[.]
NOTE
A26R45 (Xl)
A26R91 (GAIN)
A26R47 (X2)
HP 8340B/41B