Lundahl Transformers has quietly introduced a series of new transformers that were designed specifically for SE use as interstage transformers. While the LL1660, LL1692A, and LL1671 have been great transformers in my hands and in those of many others, there was performance to be gained by designing new transformers whose winding geometry has been optimized solely for single ended drivers and output stages.
These are the part numbers, prices, and their turns ratio data. Data sheets can be accessed from the data sheet menu.
Part Turns Ratio Price (USD)
LL2746 1:2 $145
LL2753 1:1 $145
LL2756 1:1 $145
LL2762 1:1 $110
The LL2746, LL2753, LL2756, and LL2762 are also available with amorphous iron cores and/or silver wire coils at higher prices.
The LL2746 and LL2753 are designed to work with lower plate impedance tubes than the LL2756 and LL2762. The LL2756 and LL2762 are similar in application, but the LL2756 is larger and has a lower winding resistance for a given amount of primary inductance than does the smaller LL2762 (same size as the LL1660).