[AMPS] more...Tube identification

[Peter Chadwick]

	>As an example, It got to be a real pain when you'd see a simple
	>quad op-amp with a Motorhead part number ship in with the
replacement
	>LM-324 part number still attached for $11 each.

Bear in mind one rule of second source in linear IC's - most 'second
sources' aren't! Even in op amps, you can get differencs - one piece of kit
I cam across could only use Motorola MC1747 op amps, not anyone else's - a
747 is a dual 741. I saw a line of 25,000 receivers built with National's
LM3089 FM receiver IF chip that didn't work; the design was done with RCA's
CA3089, which was supposed to be identical. Some nuances of processing or
design can lead to the 'second source' working fine in the same test
circuit, but not in the field.

Same with EF86's in audio. And look at the variations in 3-500's from the
various manufacturers - which is all why many of the bigger companies do
have their own stock numbers, rather than specify generic tube, transistor
or IC types.

73

Peter G3RZP


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