voltage regulation

[tin man]

Need another opinion, this problem surfaced in the last 25 hours
Battery and connections in excellent condition
Newer Vans Alternator (100 hours)
Newer Vans cheapo voltage regulator (100 hours)
System charge fluctuates between 14.5 and 15.0 volts
Instrument lights fluctuate
Audable fluctuating humm in headset when xmitting.
If isolating alternator on split master noise goes away.
Ground wire and diode good on alternator. no changes to wiring in 10 years ,all wires check out.
I'm guesssing cheapo regulator, what you all say?
Thanks
Tom

Tom, I think you're on the right track; that regulator ought to be holding perhaps 14.3 - 14.5 volts under whatever combination of loads you apply, assuming the alternator and other components are in good health. The brightening/dimming lights, and fluctuating bus voltage, both tell me that the regulator is on its way south. I suppose it could also be an out of control alternator that is working the regulator beyond its abilities, but in that case I would expect VERY high output voltages and a regulator that simply gave up the ghost and died in a more spectacular fashion that what you describe.

I run the Van's 60 amp IR alternator, and bus voltage holds at 14.4 when the engine is at cruise RPM, regardless of whether the load is 6 amps (the low end of normal, in flight load) to 20 amps (max load I've seen in flight).

Might also want to check/inquire on the AreoElectric list, you'll get some sound feedback there too. This is just my $0.02 Good luck!