The peak programme meter (PPM) indicates not average levels, but peaks. It is widely used to establish correct transmission levels and for equipment line up. It takes the form of a moving coil milliameter with an approximately linear scale, and is designed for use with an appropriate driver circuit to give a fast response and slow fall time, with the drive circuit PCB mounted directly onto the studs on the back of the meter. All Sifam PPM’s have taut band movements (ligament suspended), which is extremely robust and shock proof.
General characteristics:
| Sensitivity: |
1mA ± 1% |
| Resistance: |
600 ohms ± 5% |
| Dynamic characteristics: |
When a current of 0.93mA is rapidly applied to the indicator when connected in series with 100k ohm non-reactive resistance, the pointer over-shoot is not to exceed 5% of the steady reading. 0.93mA corresponds to 7 on the scale. |
| Scale: |
BBC 1-7, white characters on black background |
| Performance: |
onforms to BS 6840, part 10, 1991 and IEC 268-10:1991, BBC specification ED1542. |
Type 74B
Twin movement meters for back-of-panel mounting only. Red and green pointers, and is usually used for stereo monitoring, with red for left and green for right channels. Illumination is possible with a yellow LED array, supplied as a complete assembly which replaces the clear plastic window in the top of the meter case. Requires only 4mm additional clearance above top of meter. Requires 12-15 volts DC, 80mA.
Note: Sifam have ceased manufacture of PPM’s. Their replacement is the "Fast Response" series, which have a similar performance although do not fully conform to the IEC/BS standards. There is no equivalent to the twin needle type 74’s in the new series. Meters and accessories are only available whilst stocks last.