Hallicrafters HT-33B Linear Amplifier

I have been working on this amplifier for quite some time now. It is far from being original at this point. The biggest change is that it now uses a 4CX1000A instead of a PL-172. The 4CX1000A is much more available and has about the same performance. I'm leaving the pictures very large so you can get the details.

	The most obvious thing here is the 4CX1000A in the forground. In the background (left) you can see the plate transformer - 6000v CT. To the right of that is a new swinging choke for the power supply from Peter Dahl. The old one had an internal short.
	Here you can see the filter capacitor that I have to make out of discrete components. The original one was a 10 uF / 5000v oil filled capacitor. It started leaking so it had to go. I made this one out of ten 100 uF / 450v caps in series with divider resistors. The large voltage divider resistors in the foreground are for the screen supply circuit.
	This picture is a little small but it shows the amp sitting on a hand cart. The new 15kv teflon high voltage wiring is visible running from the plate transformer to the 3B28 plate caps.
	Here's a view of the underside showing the box fan for cooling the PA. The transformer in the lower left corner supplies the low voltage for the pilot lamp string. It had to be added because the 4CX1000A has the filament internally connected to the cathode, consequently the filament supply could no longer have one side grounded. The new transformer for the pilot lamps does.
	Another view of the botton shows the antenna relay that was added (with the orange jumper wire). The whole T/R switching circuitry is new.
	Here's a top view showing the new capacitor that I built on the left and the plate transformer (center) and the swinging choke on the right.