Marantz 7T Preamp Transistors

[mtflycaster]

All seem to be labeled with Marantz part numbers, rather than actual transistor designations. Has anyone out there decoded these and ID'd one or more substitutions?

F34 1019
F34 1020
F34 1021
F34 1022
F34 1023
FDTM1A
FDTM2
FDTM3

Thanks in advance!

MTfly

 

[mtflycaster]

Anyone?

OK. Well, I've kinda figured out that there are likely many possible transistor substitutes based on the requirements of the circuit design and operating parameters.

Just gotta figure out what those are!

 

[Don S]

Transistor substitutions may be hard to come by. I believe that the 7T used germainium transistors. They have a much lower Vbe than silicon, which would require a complete rework of the circuit values. Someone please correct me if I am wrong.

Don S

 

[john curl]

They should be silicon transistors.

 

[mtflycaster]

Hi John and Don -

I think silicon, also. They don't have metal or "black glass" cases. I think made by Fairchild in mid 60's. Look like brown plastic.

Here is a picture....

Regards,

Pete