Update on 3cx800 project (into mla2500).
Tested a RS 12.6vac 3amp transformer for filament supply.
Ran 14.5 vac unloaded. Ran 13.05 vac into two 3cx800's
That's close enough to the 13.5 spec (for me). A ham that
regularly changes the Aplpha 8874's out to 3cx800's told me
about this. ( He was a 4 - but can't recall that call)
Made the new air box and tested it with 3cx800's in place.
The tube height is only abt half way up the muffin fan which
is the top of the box. It is a SMALL duct on the top half
of the fan into the box! (any ideas?????)
Air flow is there, about what a muffin can put up.
(less air, less power). I did go through the Rotron Fan
catalog and it appears for 120vac fans that model MX2A3 puts up
the most. It is on the bench for the next test.
Another fan will have to be added to cool the rest of the box.
1. I wonder why I couldn't take the 3cx800(s) to a shop and
cut horizonal slots (like 8875) and run without a box????
Certainly not going to use the full 800 watts/tube.
I understand the MLA2500 HV PS is about a 800watt rating
key down??
I would like to not use the RS transformer as it must be outboard
mounted. If I could find a good regulator for 13 to 13.5 VDC/3amps, could
take the existing filament taps into a doubler and play the game that way.
Haven't changed the timer- will manually let the tubes warm 3 minutes
for the RF test. Will handle those type changes afterRF test.
--
73 Robert W5AJ w5robert@blkbox.com
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