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. All types as standard have the BBC 1-7 scale.
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: |
White characters on black background |
| Pointer: |
White (except types 74 – see below) |
| Performance: |
Type 32 conforms to BS 6840, part 10, 1991 and IEC 268-10:1991. Type 74 conform to BBC specification ED1542. |
Transparent acrylic case front, for back-of-panel mounting. Front zero-adjust screw. The bezel is matt black finish die cast alloy, and clamps onto the meter movement using two simple screw fixings. These are vertically offset to permit close lateral positioning of more than one meter. These may be illuminated with a white LED array, supplied as a complete bracket/LED assembly which mounts directly onto the meter, available in both 12 or 24 volt versions (60mA).
Twin movement meters for back-of-panel mounting only. Type 74A has one white and one orange tipped pointer, and is usually used for sum/difference monitoring, with white for sum and orange tipped for difference. Twin PPM drive card 58-322 is specifically designed to fit onto this meter, and offers left/right and sum/difference metering.
Note: Sifam have ceased manufacture of PPM’s. There is no equivalent product. These items are suitable as replacement parts only (available whilst stocks last) due to a lack of available drive cards and some illumination kits.