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 (except Type 14) have taut band movements (ligament suspended), which is extremely robust and shock proof. All types as standard have the BBC 1-7 scale.
||1mA ± 1%
||600 ohms ± 5%
||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.
||White characters on black background
||White (except types 74 – see below)
||Type 32 conforms to BS 6840, part 10, 1991 and IEC 268-10:1991. Types 22 and 24 conform in all details other than scale and pointer lengths (the BS and IEC specifications define this as 80 ± 5 mm). Type 74 conform to BBC specification ED1542.
Types 22A and 32A
Transparent acrylic case front, for front of panel mounting. Front zero-adjust screw.
Types 22AF and 32AF
Similar to types 22A and 32A, but adapted for back-of-panel mounting. 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. A lampholder and mounting bracket assembly is available to allow meter illumination, this is supplied without lamp, 12 or 24 volt festoon bulbs should be ordered separately as required. Alternatively, 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 and 24 volt versions (60mA).
Twin movement meters for back-of-panel mounting only. Type 74B has red and green pointers, and is usually used for stereo monitoring, with red for left and green for right channels. 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. 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. Twin PPM drive card 58-322 is specifically designed to fit onto this meter, and offers left/right and sum/difference metering.
Scale plates and spare glasses
Alternative scale plates are available for certain meters, and can be retro-fitted (with care!). Spare front glasses/plastic covers are also available.
||Calibrated –12, –8, –4, TEST, +4, +8, +12dB
||Calibrated –36, –30, –24, –18, –12, –6, TEST, +6, +9dB.
Note: Sifam have ceased manufacture of PPM’s. There is no equivalent product.