Question about FETs and MOSFETs - equivalents???

[frequencycentral]

Hi, I'm planning to build this tube VCF circuit, hopefully to develop a tube FSH:



I just recieved four 5672 tubes in the post today - NOS, made in 1958!

My question: for the BS107 (MOS)FET in the VCF circuit, can I use any FET or must it be a MOSFET.

Here are the FETs I have in my parts stock:
J201
BF245B
BF245C
2N5457
2N5458
2N5459
2N5461

Can I use any of these? Or must I get some BS107?

Also, must the diodes be 4007? I only have 1N4148, can I use these?

I found the schematic here: http://electro-music.com/forum/viewtopic.php?highlight=tube+vcf&t=23067

Here's the tube data: http://www.nj7p.org/Tube4.php?tube=5672

Thanks!

[flo]

Any N-channel enhancement MOSFET is a likely candidate. Check the data-sheets for the pin-out because they can vary. Put the FET on a socket so you can try a few.
It seems to be used as a variable resistor. So the Vgs-Rds transfer characteristic is important.
The FETs you listed are N-channel JFETs which, I think, are too different and therefore not usable but I'm not an expert on this...

BS170
2N7000
IRF5210
IRF520
are all n-channel enhancement MOSFETs.

[frequencycentral]

Thanks flo, I kind of figured that. 

I know virtually nothing about FETs of any type.............

I won't be building this today then!

[demonstar]

I don't by any means claim to be an expert in this field but by looking at the datasheets it appears that the BS170 would not be any good. They appear to be quite different. Well I think thats one MOSFET ruled out. 

[stm]

I would dare to say that you can use a 2N5459, provided your control voltage goes from 0 down to -3.5V or so (i.e. negative control voltage).
In this way you should get some operation from the circuit.