CABL Forum - Re: Mag 550 Mhz LEs & Amps

The DC CURRENT draw to the 8-PS power supply is .71A for the 6-T550 (power doubling trunk with the GOLD cover sticker) and 1.2A for the 8-T550 (feedforward trunk with the BLUE cover sticker).

Depending on if you are using a 8-PS, 9-PS (regulated) or a 7-PS (transformer with selectable taps) this could change if the 7-PS is not correctly set for the AC input voltage range for proper regulation.

If you are refering to the actual AC current draw of the above mentioned trunk stations, this will differ depending on the line voltage (AC) and if you are using a "Full House" (Trunk, AGC/ASC, Bridger and Return Amp). The entire loaded station would probably be in the 1.5A-2A AC range on a 60V system under normal circumstances and if you were using the 7-PS or the 8-PS. God help you if you have the 4-PS as it would bring in money at a museum!

The LE's will vary depending on if it has a return amplifier installed, is using any type of AGC/ASC or is just a standard unit. It would be safe to allow .75-amp (AC) draw or less for an LE at 60V.

Magnavox/Philips rated their amplifiers based on WATTS drawn and a calculation was necessary to get exact draw numbers with respects to AC current. The different DC power supplies were calculated based on a regulated DC window that would operate within the manufacturer specification limits. If you had a 7-PS (for example) and were using a NON-True RMS voltmeter, you voltage settings were incorrect causing poor regulation and HUM. That is another reason the 8-PS and 9-PS (regulated) supplies were introduced. Kind of like an automatic transmission in a car compared to a standard transmission, it keeps the engine (power supply) running at a more efficent level.

Sorry for the "soap box"! Good luck.

Greg Tobin
Interactive Broadband Technical Services, LLC
(Ex-Philips/Magnavox FE)

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Re: Mag 550 Mhz LEs & Amps