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G8MNY > TECH 30.12.02 21:01l 22 Lines 901 Bytes #999 (0) @ WW
BID : 35057_GB7CIP
Read: GUEST OE7FMI
Subj: 12V System Surge protection
Path: DB0MRW<DB0ERF<DB0MGB<DB0TGM<DB0IUZ<DB0GOS<ON0AR<WB0TAX<GB7ESX<GB7MAX<
GB7COV<GB7CIP
Sent: 021230/1016Z @:GB7CIP.#32.GBR.EU #:35057 [Caterham] $:35057_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
On 24cms ATV repeater GB3HV, we used the high current RS diode protectors,
RS 239-494 which is a 15V diode, designed to blow S/C & can handle pulse
currents of 75A. This was even thought we had a car battery connected as well,
we were worried about lightening spikes.
When the SMPSU blew up some years ago it put it's 60V rail on to the battery
blowing the series 30A bolted in fuse, & applying the 60V to all the 12V kit.
The spike zeners did their job & blew all the individual unit fuses. Only the
odd unprotected control transistor got zapped.
This protection certainly saved 300 pounds worth of expensive 23cm silicon
from burning out!
The SMPS is now crowbar protected with extra fuses so there is a fuse on PSU
+60V rail, then the Crowbar, PSU-Batt fuse, fuse for the battery to load
wiring, & individual unit fuses.
73 De John, G8MNY @ GB7CIP
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