The 6BE6 has a transconductance, as an oscillator, of 7250 umhos while the 6BY6
has a transconductance of 1900 umhos, as a Class A amplifier.

Different critters designed for different purposes. Each will work in the
other's circuit, but at reduced performance.

You can compare their specifications he
http://www.pmillett.com/tubedata/HB-3/Receiving_Tubes_Part_1/6BE6.PDF



Tim Shoppa wrote:

Is there any obvious choice in 6BY6 vs 6BE6 in a product detector?

I've subbed one for the other in replacement uses and there wasn't any
hugely obvious differences, but maybe if someone told me what to look
for... :-)

Tim KA0BTD