Wavetek 147 Spezifikationen PDF herunterladen (Seite 338)

Application Notes: Forward Sweep and Balance

314

No Communication

• Verify the appropriate telemetry; keep it high and located in the

passband. Watch out for sharp diplex filter roll-off and old 550 MHz

passives in a 750 MHz system. The minimum level for telemetry is

approximately 15 dBmV and the max is approximately +12 dBmV. We

sometimes lose communication on input test points because of the lack

of gain from the active and the test point loss. Use the spectrum mode

with "max hold" on to verify the existence of the telemetry and the level.

Make sure test point compensation is 0.

• Verify test equipment connections, amplifier continuity, active gain, and

that no terminators are installed. Just use the "level" mode to see if

actual channels are present. If so, then there must be continuity.

• Verify the instrument is sweeping in the correct direction. Press the right

diamond key and look in the upper right corner of the field unit display.

• Press "Sweep" on the Tx. (Sometimes it’s the little things that kill.)

• Firmware versions must be the same on the transmitters and receivers.

Bad Response

• Verify accessories are operating correctly such as cable, push-ons,

DDC-20, pads, etc.

• Low sweep points may get confused with the noise floor, especially after

going through more actives with their associated noise figures. This

could cause the "grassy" effect on the sweep display. Increase the

sweep insertion level on the Tx to verify.

• Use "Stealth" sweep instead of "Sweepless" sweep. The wrong mode

could lead to problems.

• If input levels are too high, this could cause extreme intermodulation

distortions, which could affect the associated sweep points.

Faster Forward Sweep

CAUTION ! These are only suggestions and discretion

must be used.

• Disable the Reverse Sweep and Ingress Broadcast if present

(CONFIGURE; SWEEP TRANSCEIVER.)

• Don’t sweep the video frequency of a scrambled channel. Leave it

enabled, but don’t use it as a sweep point. Insert another channel at the

audio frequency, change the type to "single channel" instead of

"scramble", and use it as a sweep point. This assumes the audio is

stable.

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Wavetek 147 Spezifikationen Seite 338