Small Broadcast station troubleshooting

[AdvancedDataServices]

Can anybody point me in the right direction on where to learn about head end broadcast equipment? As the local IT guy, i've been able to replace ends and splitters, but recently the troubles have become more complex and are dealing with GainMasters and A/V Modulators. Everybody i've talked to locally says they had OJT and were unhelpful with me aquiring my own knowledge. Any recourses (books, online universities, etc) you can direct me to, free or paid, will be greatly appreciated.

Thanks