Roger has a good point about the warm up time of most rectifier tubes,
although I have found the delay is a matter of seconds and helps a lot.

For better protection, it is easy to substitute indirectly heated rectifier
tubes for the 5Y3. The 5V4 and the 5Z4 are two tubes that can be
substituted - although it is important to verify that the output is taken
from pin 8.

The 5AT4 may be substituted for the 5U4 in many cases, but be sure to look
at the specifications to confirm it will work. I recall that Eico used the
5AR4 in some of the ham rigs, but the tube manual I grabbed does not have
that one.

We used to consider mica caps as "forever", but the smaller ones are now
fair game.

73, Colin K7FM


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