Transistor Substitution

[tehfunk]

I am looking for a substitution for the elusive 40006 germanium transistor. I have stumbled across the 2N1637, and from my newbie eyes some of the characteristics look similar and was wondering if it would be a suitable substitution, and what would be the noticeable differences. I'm aware that you can find an NTE substitution but I was looking for something vintage first.

Also, just a general question, what are the main figures that should be consistent when looking for replacement transistors? Thanks.

[petemoore]

  Small Bear has tested transistors, and document the leakage and gain for you.
  GEO has "Technology of the Fuzz Face" Article, see 'Choosing transistors for the Fuzz fAce".
  Brand #'s...if you know 'em you know 'em...IOW...I don't and don't use the markings on the transistor for much other than knowing what type of transistor it is.
  The performance from unit to unit from transistors from a batch with identical markings...varies.
  What actually matters depends on the usage and the circuit, but leakage and gain are the 'scrutinization' numbers..after that there's a bit of frequency gain differences [not much] but HF's can easily be tamed..
  What's the plan ?

[tehfunk]

My plan is to make an envelope filter, which uses the 40006, a seemingly impossible to find transistor so I wanted to make a vintage substitution rather than a nte or similar modern replacement transistor. Thanks for the help, but I still would like to know if you guys think it would work out well.