Henry's East Ealing Site

Updated: 10 May 2004 -- 30S-1 page added

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I had long admired the 30S-1 from afar, so to speak, but as they are very rare in the UK, I had assumed that I never would possess one.  I was therefore very pleased when another amateur friend offered to sell me his.

The amplifier is designed around the 4CX1000A tube, and will generate 1KW PEP with ease requiring about 60W input.  The tube runs with plenty idling current, so at lower power outputs, is almost in Class A. 

Tube.jpg (63846 bytes)                          Tank.JPG (87529 bytes)

As can be seen from the picture above, the tank capacitors are generous in size.  The tube anode is connected by a metal ring and not the usual anode cap.

A great deal of protection circuitry is built in including a thermal probe in the air flow from the tube.  The HV is provided a large removable transformer and a pair of 3B28 mercury vapour rectifiers.  In all the amplifier is very professionally designed and constructed, as was evinced by it's military and commercial usage.

Front.JPG (64240 bytes)                  shack.JPG (89842 bytes)

With the front panel removed the power supply and protection/relay circuitry can be seen.  Also note the interlock rod, protruding from the panel  below the fuses.  The tube bias and filament voltage are adjustable by controls on the panel.

I have been fortunate as a previous owner sat the amplifier on a metal frame with large castors, enabling me to manipulate it around my small shack.