The AM Forum

While looking at this schematic:

http://www.amwindow.org/tech/htm/valiant/ps.htm (http://www.amwindow.org/tech/htm/valiant/ps.htm)

While it is clear to me that I need to add 8-10 1N5408 diodes in the location marked "add" I am not sure what to do with the diodes marked "OEM" are these the 866's that will be removed?

In regard to the 100 mf 450 VDC caps should these be electrolytic caps?
Where does on find 100k 2 watt resistors I have not been able to locate them thus far do these have to be carbon resistors or can I use wire wound here?

Thanks
Happy Holidays!

Just looked at the schematic.

There are two sets of diode rectifiers, one set for the final PA and a separate rectifier set for the modulator.  It's two HV supplies running off the same transformer.

You probably don't have to use two complete diode sets.  You can run a single 4 diode string off the end of the first diode (OEM) rectifiers.  Right where the diodes and the choke are connected.  In fact, you don't even need 4 diodes, probably two will be OK since the DC voltage is nearly the same on both sides of the isolating diodes.  The only thing the extra diodes do is isolate the filter caps from the choke.  Otherwise you would end up with a capacitor input filter which will make the HV on the final much higher.

What that mod does is put a higher voltage on the modulators and keeps a lower voltage on the final PA.

The caps shown are electrolytic and the 100K 2 watters can be any type you can find.  The exact value is not important.  In fact, 2 watters may not be enough.  You can parallel up groups of two 150K-200K 2 watters and it should work OK.  The lower resistance will add a little more bleeder current and help to keep the voltage more equal across each electrolytic cap (which is a good thing).

the real Fred